WO2002001850A1 - Gamma correction device - Google Patents

Gamma correction device Download PDF

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Publication number
WO2002001850A1
WO2002001850A1 PCT/JP2001/005562 JP0105562W WO0201850A1 WO 2002001850 A1 WO2002001850 A1 WO 2002001850A1 JP 0105562 W JP0105562 W JP 0105562W WO 0201850 A1 WO0201850 A1 WO 0201850A1
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WO
WIPO (PCT)
Prior art keywords
gamma correction
value
correction value
gamma
stored
Prior art date
Application number
PCT/JP2001/005562
Other languages
French (fr)
Japanese (ja)
Inventor
Fumio Fujimura
Original Assignee
Matsushita Electric Industrial Co. Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Matsushita Electric Industrial Co. Ltd. filed Critical Matsushita Electric Industrial Co. Ltd.
Publication of WO2002001850A1 publication Critical patent/WO2002001850A1/en

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
    • H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
    • H04N1/40—Picture signal circuits
    • H04N1/407—Control or modification of tonal gradation or of extreme levels, e.g. background level
    • G—PHYSICS
    • G06—COMPUTING; CALCULATING OR COUNTING
    • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
    • G06T5/00—Image enhancement or restoration
    • G06T5/90—Dynamic range modification of images or parts thereof
    • G06T5/92—Dynamic range modification of images or parts thereof based on global image properties

Definitions

  • the present invention relates to a gamma correction device, and more particularly to gamma correction when an image scanner is used as an imaging device.
  • gamma correction is performed with a display device such as a monitor for displaying a captured image in order to maintain the linearity of an output signal with respect to an input signal.
  • Gamma correction is performed so that the characteristics become linear.
  • the gamma correction value for the input signal is calculated in advance, the gamma correction table is stored in ROM, and the address of ROM is referred to by the input signal. This can be realized by outputting the gamma correction data stored in the address as an output signal.
  • This gamma characteristic differs for each element of the image scanner.However, most image scanners perform gamma correction with only one gamma correction value, and color differences may occur in scanned images due to differences in gamma characteristics for each element. Image quality degradation such as streaks and streaks has occurred.
  • shading correction has been performed to suppress the variation in the element characteristics.
  • variations in element characteristics can be suppressed by correcting the black level and white level of each element.
  • the image quality was degraded due to the characteristic variation of “1”.
  • the purpose of the method is not to reduce the capacity of the gamma correction table for each element, but the device has several types of gamma correction tables.
  • To reduce the size of the collection table there is, for example, a digital gamma correction method and an apparatus thereof disclosed in Japanese Patent Application Laid-Open No. 8-195895.
  • FIG. 28 is a block diagram showing a conventional device for performing gamma correction.
  • 280 1 is an input terminal to which data is input
  • 280 2 is an input terminal 280 1
  • the selection section, 2803 is a gamma characteristic correction section that processes the signal output from the input selection section 2802
  • 284 is the characteristic selection section
  • 2805 is the characteristic selection section 28004
  • the microprocessor 28006 that receives the output of the microprocessor 280 is a data storage unit that supplies data to the microprocessor 285.
  • Reference numerals 280 (1) to 280 (M) denote memories constituting the data storage unit 2806.
  • the data storage unit 2806 stores data of M gamma correction tables, and each gamma correction table stores one reference data and a plurality of difference values. Based on the gamma characteristic selection signal supplied from the characteristic selection unit 284, the microprocessor 285 selects reference data stored from the memory corresponding to the gamma characteristic selected from the data storage unit 286. , And a plurality of difference values are read.
  • the microphone processor 28005 restores the gamma characteristic table using the read reference data and a plurality of difference values, and the gamma characteristic correction section 2803 uses a look-up table form. save. Then, the gamma characteristic correction unit 2803 performs gamma correction by using the input video data as address data and outputting a gamma correction value corresponding to the address.
  • the storage capacity is reduced by storing the reference data and a plurality of difference values.
  • the data storage unit 286 stores the gamma correction value G (1) corresponding to the input data X (1) as the reference data, and stores the remaining data.
  • the gamma correction value is
  • the gamma correction data can be restored by integrating the k-th difference value from the reference data.
  • the storage capacity can be reduced.
  • the conventional gamma correction device has a problem that the storage capacity does not decrease in the low gradation region, that is, in the region where the value of the input data is small, because the amount of change in the gamma characteristic is large.
  • the gamma correction data of a certain element has the gamma correction characteristic as shown in FIG. 30 (a)
  • the difference value corresponding to input data 3 is 1 2 and the difference value corresponding to input data 4 is 6.
  • the capacity for storing the difference value must be such that the maximum value of the difference value can be stored. In this case, a storage capacity of 5 bits is required to store 17. In this way, when the input data is small, the difference value does not decrease due to the gamma characteristic of the element, and the storage capacity of the gamma correction value cannot be reduced.
  • the conventional gamma correction device does not perform gamma correction with a different gamma correction value for each element, but performs gamma correction with the same gamma correction value for each element.
  • gamma correction could be performed by preparing multiple gamma correction tables, different gamma corrections could not be performed for each element.
  • the conventional gamma correction device is configured as described above, and the same gamma correction table is prepared for each element, and the gamma correction is performed, so that the image quality deterioration cannot be sufficiently prevented.
  • the difference value does not become small due to the gamma characteristic of the element, and the storage capacity of the gamma correction value cannot be reduced efficiently.
  • the present invention has been made in order to solve the above problems, and has a high precision
  • 'To provide a gamma correction device capable of performing correction.
  • the storage capacity of the gamma correction value is small. It is an object of the present invention to provide a gamma correction device capable of: Disclosure of the invention
  • a gamma correction device is a gamma correction device for correcting gamma characteristics of a plurality of image sensors, wherein a gamma correction value storage for storing gamma correction values of all image sensors. Means, a gamma correction value selecting means for selecting a gamma correction value for each element from the gamma correction value storage means, and a gamma correction value selected by the gamma correction value selecting means for each element.
  • Gamma correction means for individually performing gamma correction.
  • the gamma correction device is the gamma correction device according to claim 1, wherein the gamma correction value storage means includes a discrete input device that reads a predetermined image. A gamma correction value for each element is stored, and an interpolation process is performed from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means to calculate a gamma correction value for each element. It has gamma correction value interpolation means.
  • the gamma correction device is the gamma correction device according to claim 1, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image.
  • the gamma correction value for an appropriate input value the gamma correction value for a low gradation part is stored more.
  • a gamma correction device is a gamma correction device for capturing gamma characteristics of a plurality of imaging devices, wherein the gamma correction value of the reference device and each of the devices that are positionally adjacent to each other.
  • Gamma correction value storage means for storing the difference value of the gamma correction values of the above with a predetermined storage capacity, the reference element uses the stored gamma correction value, and the other elements use the gamma correction of the reference element.
  • Gamma correction value calculation means for calculating a gamma correction value for each element by integrating the difference value of the element existing up to the position of the element with the value, and a gamma correction value calculated from the above calculated gamma correction value for each element.
  • gamma correction means for performing gamma correction is provided.
  • the gamma correction device is the gamma correction device according to claim 4, wherein the gamma correction value storage means includes a predetermined image. A gamma correction value corresponding to a discrete input value obtained by reading an image is stored, and an interpolation process is performed based on the input value and the gamma correction value of a predetermined image stored in the gamma correction value storage unit. The gamma correction value interpolation means for calculating the gamma correction value for each is provided.
  • the gamma correction device is the gamma correction device according to claim 4, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image.
  • the gamma correction value for an appropriate input value the gamma correction value for a low gradation part is stored more.
  • a gamma correction device is a gamma correction device for capturing gamma characteristics of a plurality of image pickup devices, wherein a gamma correction value of a reference device and a device that is each positionally adjacent to each other.
  • the difference value of the gamma correction value of the above is stored in a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, the adjacent element exceeds the predetermined storage capacity by the difference value.
  • the gamma correction value storage means that adds and stores the value, and the reference element uses the stored gamma correction value, and the other elements use the gamma correction value of the reference element up to the position of the element.
  • Gamma correction value calculating means for calculating a gamma correction value for each element by integrating the differential values of the elements to be corrected, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. It is provided with.
  • the gamma correction device is the gamma correction device according to claim 7, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image. The gamma correction value for the input value is stored. The gamma correction value is interpolated from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means, and the gamma correction value for each element is obtained. It is provided with a gamma correction value capturing means for calculating the gamma correction value.
  • the gamma correction device is the gamma correction device according to claim 7, wherein the gamma correction value storage means is configured to read a predetermined image.
  • the gamma correction value for a typical input value the gamma correction value for the low gradation part is stored more.
  • the gamma correction device includes a plurality of imaging elements.
  • a gamma correction device that corrects the gamma characteristic of a child, the average value of the gamma correction value of each element for each input value and the difference value between the average value and the gamma correction value of each element are stored.
  • gamma correction means for performing gamma correction for each element.
  • the gamma correction device is the gamma correction device according to claim 10, wherein the gamma correction value storage means reads a predetermined image from a discrete image. A gamma correction value corresponding to a typical input value is stored. A gamma correction value is calculated from the input value of the predetermined image stored in the gamma correction value storage means and the gamma correction value. It is provided with a gamma correction value capturing means for calculating the gamma correction value.
  • the gamma correction device is the gamma correction device according to claim 10, wherein the gamma correction value storage means reads a predetermined image.
  • the gamma correction values for discrete input values are stored more.
  • a gamma correction device is a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, wherein the gamma correction value of a reference element and a gamma correction value of a reference element are each different.
  • a gamma correction value storing means for storing a difference value between a gamma correction value between adjacent elements and a data length of the difference value; a reference element performs gamma correction by using a stored gamma correction value; For other elements, a gamma correction value calculating means for calculating a gamma correction value for each element by integrating a difference value of an element existing up to the position of the element with a gamma correction value of the reference element.
  • Gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
  • the gamma correction device is the gamma correction device according to claim 13, wherein the gamma correction value storage means reads a predetermined image from a discrete image. A gamma correction value corresponding to a typical input value is stored, an interpolation process is performed from the input value of a predetermined image stored in the gamma correction value storage means and a gamma correction value, and a gamma correction value for each element is calculated. Equipped with gamma correction value capture means to calculate It is a thing.
  • the gamma correction device according to claim 15 of the present invention is the gamma correction device according to claim 13, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image.
  • the gamma correction value for a typical input value is stored, the gamma correction value for the low gradation part is stored more.
  • a gamma correction device is a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, wherein the gamma correction table storage means stores a plurality of gamma correction tables.
  • Gamma correction table selection information storage means for storing selection information for selecting a gamma correction table for each element; gamma correction table storage means; gamma correction table selection information storage means; A gamma correction table selecting means for selecting a gamma correction table corresponding to each child, and a gamma correction means for performing gamma correction based on the selected gamma correction table.
  • the gamma correction device is the gamma correction device according to claim 16, wherein the gamma correction table storage means has a gamma correction amount.
  • the gamma correction table with the smallest gamma correction amount or the gamma correction amount with the largest gamma correction amount is stored as the reference gamma correction table, and the other gamma correction tables are those whose reference gamma correction table has the smallest gamma correction amount.
  • the correction table when the gamma correction tables are arranged in ascending order of the gamma correction amount, the difference value of the adjacent gamma correction values is stored.On the other hand, the gamma correction amount is used as a reference gamma correction table.
  • the gamma correction tape Storing the difference value meets gamma ToTadashichi, those having a gamma correction table calculating means for calculating the gamma correction table and a gamma capturing positive table and the difference value of the reference.
  • the gamma correction device is the gamma correction device according to claim 16, wherein the gamma correction table selection means includes: The gamma that minimizes the least square sum of the gamma correction values with a plurality of gamma correction tables stored in the gamma correction table storage means This is to select a capture table.
  • a gamma correction apparatus is a gamma correction apparatus for correcting gamma characteristics of a plurality of imaging elements, wherein the gamma correction apparatus outputs an output characteristic correction value for an input value of a reference element before gamma correction.
  • An element characteristic that stores a certain element characteristic correction value and a difference value of an element characteristic correction value, which is an output characteristic correction value with respect to an input value before gamma correction, between elements adjacent in position with a predetermined storage capacity.
  • the correction value storage means and the reference element calculate a gamma correction value based on the stored element characteristic correction value, and the other elements exist in the element characteristic correction value of the reference element up to the position of the element.
  • An element characteristic calculation means for calculating a gamma correction value for each element by integrating the element difference values, and a gamma correction value for each element based on the calculated characteristic correction value for each element.
  • a calculating gamma correction value calculating means in which a gamma ToTadashi means for performing gamma correction for each element from the gamma correction value calculated above.
  • the gamma correction device according to claim 20 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic storage means is configured to determine a position between adjacent elements in position.
  • the difference value of the element characteristic correction value is stored in a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, an adjacent element adds and stores the excess value to the difference value. .
  • the gamma correction device is the gamma correction device according to claim 19, wherein the element characteristic correction value storage means is configured to correct element characteristic correction of the element.
  • the average value of the values and a difference value between the average value and the element characteristic correction value for each element are stored, and the element characteristic correction value calculating means converts the element value into an average value of the element characteristic correction value for each element.
  • the element characteristic correction value is calculated from the value obtained by adding the difference value for each element.
  • the gamma correction device is the gamma correction device according to claim 19, wherein the element characteristic storage means is a device which is positioned adjacent to the device. The difference between the element characteristic correction values is stored together with the data length.
  • the gamma correction device is the gamma correction device according to claim 19, wherein the element characteristic correction value storage means is configured to store a predetermined image.
  • the element characteristic correction value for the discrete input value obtained by reading The element characteristic correction value interpolation means calculates an element characteristic correction value for each element by performing an interpolation process from the input value of the predetermined image and the element characteristic correction value stored in the element characteristic correction value storage means. Is what you do.
  • the gamma correction device according to claim 24 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic correction value storage means stores a predetermined image. When storing the element characteristic correction value for the read discrete input value, the element characteristic correction value of the low gradation part is stored more.
  • a gamma correction device that corrects the gamma characteristics of a plurality of imaging devices stores gamma correction values of all imaging devices.
  • Gamma correction value storage means e.g., a gamma correction value storage means, gamma correction value selection means for selecting a gamma correction value for each element from the gamma correction value storage means, and an element using the gamma correction value selected by the gamma correction value selection means.
  • a gamma correction unit that performs gamma correction individually for each device is provided.By performing gamma correction for each device, the gamma characteristics of the device can be corrected, and more accurate gamma correction can be performed. The effect that it can be obtained is obtained.
  • the gamma correction value storage means includes a discrete image read from a predetermined image. A gamma correction value for a specific input value is stored, and an interpolation process is performed based on the input value and the gamma correction value of a predetermined image stored in the gamma correction value storage means to calculate a gamma correction value for each element. Since gamma correction value capturing means is provided, only gamma correction values for discrete input values are stored, so that gamma correction can be performed for each element with a small storage capacity. Is received.
  • the gamma correction device in the gamma correction device according to claim 1, the gamma correction device according to claim 1, the gamma correction device according to claim 1, When the correction value storage means stores the gamma correction value for the discrete input value obtained by reading the predetermined image, the gamma correction value for the low gradation part is stored more, so that the amount of change is large. By storing more gamma correction values in the low gradation area, gamma correction can be performed for each element with less storage capacity and high accuracy. The effect that can be performed is obtained.
  • a gamma correction value of a reference device in a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, a gamma correction value of a reference device and a device that is positionally adjacent to each other
  • a gamma correction value storage means for storing a difference value between two gamma correction values with a predetermined storage capacity, and a gamma correction value stored as a reference element.
  • Gamma correction value calculating means for calculating a gamma correction value for each element by integrating the difference value of the element existing up to the position of the element with the gamma correction value, and a gamma correction value calculated from the calculated gamma correction value.
  • gamma correction means for performing gamma correction is provided for each element, the difference between the gamma correction values of elements adjacent in position is stored in a predetermined storage capacity, so that efficiency is improved. There is an advantage that it is possible to perform the gamma correction for each element in the absence storage capacity.
  • the gamma correction value storage means stores the discrete image obtained by reading a predetermined image.
  • the gamma correction values for the various input values are stored, and interpolation processing is performed from the gamma correction values and the input values of the predetermined image stored in the gamma correction value storage means to calculate the gamma correction values for each element.
  • Gamma correction value interpolation means for storing the difference value of the gamma correction value of the element adjacent in position with a predetermined storage capacity, and furthermore, only the gamma correction value for a discrete input value is stored.
  • the gamma correction value storage means reads a predetermined image from a discrete image.
  • the gamma correction value storage means reads a predetermined image from a discrete image.
  • the gamma correction value of the reference device in the gamma correction device for correcting the gamma characteristics of a plurality of imaging devices, the gamma correction value of the reference device And the difference value of the gamma correction value between the elements adjacent to each other with a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, the difference value is calculated for the adjacent element.
  • the gamma correction value storage means for adding and storing the excess value, and the reference element uses the stored gamma correction value, and for the other elements, the gamma correction value of the reference element is added to the position of the element.
  • Gamma correction value calculation means for calculating a gamma correction value for each element by integrating the difference values of the existing elements, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
  • the gamma correction value storage means stores a discrete image obtained by reading a predetermined image.
  • the gamma correction values for the various input values are stored, and interpolation processing is performed from the input values of the predetermined image and the gamma correction values stored in the gamma correction value storage means to calculate a gamma correction value for each element. Since the gamma correction value interpolation means is provided, even if the difference value exceeds the capacity for storing the difference value, the error can be minimized. Storing the correction value has the effect of reducing the storage capacity of the gamma correction value.
  • the gamma correction value storage means reads a predetermined image and stores the discrete image.
  • the gamma correction value storage means reads a predetermined image and stores the discrete image.
  • the gamma correction of each element for each input value is provided.
  • Gamma correction value storage means for storing an average value of the gamma correction values, a difference value between the average value and the gamma correction value for each element, and a gamma correction value for each element.
  • Gamma correction value calculating means for calculating a difference value for each element to calculate the gamma correction value, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. Since the gamma correction value is calculated by adding the difference value to the average value independently for each element, it is possible to perform the gamma correction accurately.
  • the gamma correction value storage means stores a predetermined image.
  • a gamma correction value corresponding to the read discrete input value is stored.
  • Interpolation processing is performed from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means, and the gamma correction for each element is performed.
  • the gamma correction value interpolation means for calculating the correction value is provided, so that the gamma correction value can be calculated by adding the difference value to the average value independently for each element to calculate the gamma correction value. Also, by storing the gamma correction value for the discrete input value, the effect of reducing the storage capacity of the gamma correction value can be obtained.
  • the gamma correction value storage means stores a predetermined image.
  • more gamma correction values for the low gradation area are stored, so the difference value is added to the average value independently for each element.
  • the gamma correction value can be calculated to accurately perform gamma correction.
  • more low-gradation parts with a large change amount are stored more accurately to achieve storage capacity. Therefore, the effect of being able to reduce is obtained.
  • a gamma correction value of a reference element and a gamma correction value of a reference element are each set.
  • Gamma correction value storage means for storing the difference value between the gamma correction values of adjacent elements, the data length of the difference value, and the reference element perform gamma correction based on the stored gamma correction values.
  • the difference value of the element existing up to the position of the element is added to the gamma correction value of the reference element, thereby obtaining the element
  • Gamma correction value calculating means for calculating a gamma correction value for each element, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value are provided.
  • the gamma correction value storage means reads a predetermined image.
  • a gamma correction value for a discrete input value is stored.
  • the gamma correction value is interpolated from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means, and the gamma correction value for each element is obtained.
  • the gamma correction value interpolating means for calculating the gamma correction value is calculated, so that the difference value of the gamma correction value of the element adjacent in position is efficiently stored according to the magnitude of the difference value.
  • the gamma correction value storage means reads a predetermined image.
  • more gamma correction values are stored in the low gradation area, so that more gamma correction values are stored in the low gradation area with large changes.
  • the effect that gamma correction can be accurately performed for each element with a small storage capacity can be obtained.
  • a gamma correction table storage for storing a plurality of gamma correction tables Means, gamma correction table selection information storage means for storing selection information for selecting a gamma correction table for each element, and gamma correction table storage means and gamma correction table selection information storage means for each element.
  • Gamma correction table selection means for selecting the selected gamma correction table, and gamma correction means for performing gamma correction based on the selected gamma correction table, so that the gamma correction table selection information corresponding to each element is provided.
  • the gamma correction table storage means has the most gamma correction amount.
  • a small gamma correction table or a gamma correction table with the largest amount of gamma correction is stored as a reference gamma correction table, and the other gamma correction tables are based on the gamma correction table with the smallest gamma correction amount.
  • the gamma correction table is used, when the gamma correction tables are arranged in ascending order, the difference value of the gamma correction values that are adjacent to each other is stored.
  • the gamma correction table Has a gamma correction tape loss calculating means for storing a difference value between adjacent gamma correction values and calculating a gamma correction tape loss from the reference gamma correction table and the difference value.
  • the storage capacity of the gamma correction table storage means can be reduced by storing the difference value between the gamma correction tables having similar gamma correction characteristics. The effect that can be obtained is obtained.
  • the gamma correction table selecting means includes: The gamma correction table that minimizes the least square sum of the gamma correction values is selected from the table and the plurality of gamma correction tables stored in the gamma correction table storage means. By storing only the selection information of the gamma correction table for each element, the storage capacity can be reduced and the optimal gamma correction table can be selected accurately. can get.
  • a gamma correction device for correcting gamma characteristics of a plurality of imaging elements in a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, a gamma correction device for input values of a reference element before gamma correction is provided.
  • the element characteristic correction value which is the output characteristic correction value
  • the difference value between the element characteristic correction value which is the output characteristic correction value for the input value before gamma correction, between the elements adjacent to each other, are predetermined.
  • the correction value storage means and the reference element calculate the gamma correction value based on the stored element characteristic correction value.
  • the element characteristic correction value calculating means for calculating the gamma correction value for each element by integrating the element characteristic correction value of the reference element with the difference value of the element existing up to the position of the element.
  • Gamma correction value calculating means for calculating a gamma correction value for each element from the calculated characteristic correction value for each element, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
  • the gamma correction can be performed for each element with a smaller storage capacity by storing the difference between the characteristic correction values before gamma correction, where the difference in characteristics between the elements is small. 'Is obtained.
  • the element characteristic storage means includes a pair of elements adjacent in position.
  • the difference value of the element characteristic correction value of each element is stored in a predetermined storage capacity. Therefore, by storing the difference value of the characteristic correction value before gamma correction with a small difference in characteristics between elements with a predetermined storage capacity, it is possible to perform gamma correction for each element with a smaller storage capacity more efficiently. The effect is that it can be done.
  • the element characteristic correction value storage means includes: The average value of the characteristic correction values and the difference between the average value and the element characteristic correction value of each element are stored, and the element characteristic correction value calculating means calculates the average value of the element characteristic correction values of each element.
  • the element characteristic correction value is calculated from the value obtained by adding the difference value of each element, so that the difference value of the characteristic correction value before gamma correction, in which the characteristic difference between elements is small, is stored. The effect is obtained that the capacity can be reduced, and even if the difference value exceeds the capacity for storing the difference value, the error can be minimized.
  • the element characteristic storage means includes a pair of elements adjacent in position. Since the difference between the element characteristic correction values of the elements is stored together with the data length, the difference between the characteristic correction values before gamma correction where the characteristic difference between the elements is small By storing the values, the storage capacity can be reduced.In addition, for each element, a characteristic correction value is calculated by independently adding the difference value to the average value, and the gamma capture is calculated from the characteristic correction value. Since the positive value is calculated, the effect that the gamma correction can be performed accurately can be obtained.
  • the element characteristic correction value storage means reads a predetermined image.
  • the element characteristic correction value interpolating means stores the element value and the element characteristic correction value for the predetermined image stored in the element characteristic correction value storage means. Calculates the element characteristic correction value for each element by performing interpolation processing from, so that the difference value of the characteristic correction value before gamma correction where the characteristic difference between the elements is small is stored, and the discrete input value Storing the characteristic correction value has the effect of further reducing the storage capacity.
  • the element characteristic correction value storage means reads a predetermined image.
  • the element characteristic compensation IE values for discrete input values more element characteristic correction values in the low gradation area are stored, so that the characteristics before gamma correction have small differences in the characteristics between the elements.
  • the storage capacity is reduced, and by storing more characteristic correction values of the low gradation part where the amount of change becomes large after gamma correction, each element can be accurately stored with a small storage capacity. This has the effect that gamma correction can be performed.
  • FIG. 1 is a block diagram showing a configuration of a gamma correction device according to Embodiment 1 of the present invention.
  • FIG. 2 is a diagram showing a configuration of an image scanner to which the gamma correction device according to the first embodiment is applied.
  • FIG. 3 is a diagram illustrating an example of a gamma correction value of the gamma correction device according to the first embodiment.
  • FIG. 4 is a plot showing the configuration of a gamma correction device according to Embodiment 2 of the present invention.
  • FIG. 4 is a plot showing the configuration of a gamma correction device according to Embodiment 2 of the present invention.
  • FIG. 5 is a diagram showing an example of a grid used for calculating a gamma correction value.
  • FIG. 6 is a diagram showing an example of a gamma correction value for a 10-pattern gray chart.
  • FIG. 7 is a diagram for explaining an interpolation process for performing linear interpolation between data.
  • FIG. 8 is a diagram showing an example of a case where an ideal gamma curve whose gamma correction curve has a value of gamma 2.2 is linearly approximated by 10 discrete data.
  • FIG. 9 is a diagram illustrating an example of an interpolation process for minimizing an error from an ideal gamma curve by increasing the number of data in the low gradation area.
  • FIG. 10 is a block diagram showing a configuration of a gamma correction device according to Embodiment 3 of the present invention.
  • FIG. 11 is a diagram for explaining a method of calculating a difference value stored in a gamma correction value storage unit included in the gamma correction device according to the third embodiment.
  • FIG. 12 is a block diagram showing a configuration of a gamma correction device according to Embodiment 4 of the present invention.
  • FIG. 13 is a diagram for explaining a method for restoring a gamma correction value from a difference value of the gamma correction device according to the fourth embodiment.
  • FIG. 14 is a diagram for explaining a problem before using the interpolation method by the gamma correction device according to the fifth embodiment of the present invention.
  • FIG. 15 is a diagram for explaining an interpolation process using the gamma correction device according to the fifth embodiment of the present invention.
  • FIG. 16 is a block diagram illustrating a configuration of a gamma correction device according to a sixth embodiment of the present invention.
  • FIG. 17 is a diagram for explaining a difference value calculation method by the gamma correction device according to the sixth embodiment.
  • FIG. 18 is a block diagram showing a configuration of a gamma correction device according to Embodiment 7 of the present invention.
  • FIG. 19 is a diagram showing a gamma correction value storage circuit of the gamma correction device according to the seventh embodiment. It is a figure for explaining the recording method to a road.
  • FIG. 20 is an image diagram for explaining a state in which the data length of the difference value is stored together in the gamma correction value storage circuit of the gamma correction device according to the seventh embodiment.
  • FIG. 21 is an image diagram in the case of sequentially storing the data length of the gamma correction value and the gamma correction value according to the seventh embodiment.
  • FIG. 22 is a block diagram showing a configuration of a gamma correction device according to Embodiment 8 of the present invention.
  • FIG. 23 is a block diagram showing a configuration of a modification of the gamma correction device according to the eighth embodiment.
  • FIG. 24 is a block diagram showing a configuration of a gamma correction device according to Embodiment 9 of the present invention.
  • FIG. 25 is a diagram showing a relationship between element characteristics and ideal characteristics in the gamma correction device according to the ninth embodiment.
  • FIG. 26 is a diagram for explaining a difference value calculation method of the gamma correction device in the above embodiment 2.
  • FIG. 27 is a diagram conceptually illustrating a gamma correction method using a ROM storing a gamma correction table.
  • FIG. 28 is a block diagram showing a configuration of a conventional gamma correction device.
  • FIG. 29 is a diagram for explaining a gamma correction method using a conventional gamma correction device.
  • FIG. 30 is a diagram for explaining a difference value calculation method in a conventional gamma correction device.
  • FIG. 1 is a block diagram showing the configuration of the gamma correction device according to the first embodiment.
  • 101 is an image sensor such as a CCD
  • 102 is a CCD 1 0
  • a / D converter that converts the output of 1 to digital
  • 103 is the gamma correction circuit that receives the output of the AZD converter 102
  • 104 is the required gamma correction value from the gamma correction value storage circuit 105 Is a gamma correction table selection circuit
  • 106 is an element selection circuit.
  • the gamma correction is performed by the gamma correction circuit 103 using the individual gamma correction value for each device.
  • the gamma correction value for each element is stored in the gamma correction table stored in the gamma correction value storage circuit 105, and the gamma correction tape of the corresponding element is stored in the gamma correction table selection circuit 104.
  • the gamma correction circuit 103 performs gamma correction based on the gamma correction value in the selected gamma correction table.
  • the image scanner uses an image as shown in Fig. 2! : Reading. That is, in FIG. 2, reference numeral 201 denotes a read original, reference numeral 202 denotes illumination, and reference numeral 203 denotes a lens disposed between the read original 201 and the image sensor 204.
  • the reading principle is as follows.
  • the reading document 201 is illuminated by the illumination 202, the reflected light is imaged by the lens 203, and the light signal is converted into an electric signal by the image sensor 204.
  • the imaging element 204 is composed of a plurality of elements from element 1 to element N, and converts a light signal into an electric signal for each element.
  • gamma correction is performed by providing an individual gamma correction table for each element from the first element to the Nth element constituting the imaging element 204.
  • the gamma correction value storage circuit 105 stores the gamma correction table for each element.
  • the gamma correction value storage circuit 105 stores the value shown in FIG. 3 (b). It will be remembered. In this case, the gamma correction value is represented by 8 bits, that is, 1 byte.
  • the gamma correction value storage circuit 105 stores 256 gamma correction values for the input values 0 to 255 of the first element in one byte, and then the gamma correction value of the second element. Are stored in a single byte. In this way, all gamma correction values up to the Nth imaging element are stored.
  • the gamma correction table selection circuit 104 calculates the gamma correction value of the Nth element from the gamma correction value stored in the gamma correction value storage circuit 105. It is necessary to select the gamma correction value of the Nth element on the gamma correction value storage circuit 105.
  • a gamma correction table is prepared for each element in the gamma correction value storage circuit 105, and the correction table corresponding to each pixel is stored in the gamma correction table selecting means 10. Since gamma correction is selected by using 4 to perform gamma correction, highly accurate gamma correction can be performed, and deterioration in image quality can be suppressed.
  • FIG. 4 is a circuit block diagram of a gamma correction device according to the second embodiment.
  • the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and differ from FIG. 1 in that a gamma correction value interpolation circuit 404 and a pattern value storage circuit 408 are added.
  • a gray chart whose value is known in advance as shown in Fig. 5 is read from a scanner, the gamma correction value is calculated from the gray chart value and the read value, and the gray chart is calculated.
  • the gamma correction value for the input value that does not exist is calculated by interpolating the value by linear interpolation or curve interpolation.
  • the gamma correction value storage circuit 105 stores the gamma correction value for the gray chart pattern, and if the gamma correction value is interpolated by interpolating processing, the storage capacity can be reduced. be able to. For example, see Figure 5. Thus, in the case of a 10-pattern gray chart, the storage capacity can be reduced to 10/256 compared to storing gamma correction values for continuous input data from 0 to 255. . The method of calculating the gamma correction value will be described below.
  • the gamma correction value storage circuit 105 stores gamma correction values for the number of patterns for each element. For example, gamma correction values for a gray chart of 10 patterns are as shown in FIG.
  • the pattern value is the value obtained by measuring the pattern for each gradation of the gray chart with a measuring instrument.
  • the gamma correction table selection circuit 104 selects a gamma correction table for each element, and sends the gamma correction value to the gamma correction value interpolation circuit 404.
  • the gamma correction value interpolation circuit 404 interpolates the gamma correction value from the gamma correction value selected by the gamma correction table selection circuit 104 and the pattern value stored in the pattern value storage circuit 408. I do. For example, when the gamma correction value of the first element in FIG. 6 is interpolated, as shown in FIG. 7, the interpolation processing can be performed by interpolating a straight line between the data. For example, the gamma correction value Y for the pattern value X from 25 to 50 is
  • Gamma correction can be performed for each element by the gamma correction circuit 103 based on the gamma correction value interpolated by the gamma correction value interpolation circuit 404 in this manner.
  • more gamma correction values may be stored for a pattern in a low gradation area, that is, a pattern in a dark area. This is because the gamma correction curve has a large change in the low gradation area, and therefore, the gamma correction accuracy can be improved by taking more data in this area.
  • the sag chart used for calculating the gamma correction value should be a chart having more low gradation parts, that is, a chart having more patterns close to black, or a gray chart.
  • the gamma correction values in the low gradation area can be stored in the gamma correction value storage circuit 105 more. is there.
  • the gamma correction value for the discrete input data is stored in the gamma correction value storage circuit 105, and the pattern value storage circuit 4 storing the discreteness of the input data is stored.
  • the gamma correction value interpolation circuit 404 uses the pattern value including the corresponding input data from 08 and the gamma correction value stored in the gamma correction value storage circuit 105 to perform interpolation processing.
  • the gamma correction is calculated by calculating a gamma correction value, so that gamma correction can be performed for each pixel, and image quality degradation can be suppressed.
  • the storage capacity can be reduced, and costs can be reduced.
  • the error due to the interpolation processing can be reduced, and the accuracy of gamma correction can be further improved.
  • any element may be used as a reference element.
  • any number of reference elements may be provided.
  • the case where the gamma correction value corresponding to the discrete input value is stored and the case where 10 patterns of the delay chart are stored have been described, but the number of patterns is not limited to this.
  • interpolation may be performed not by linear approximation but by a curve such as a quadratic curve.
  • FIG. 10 is a block diagram showing the configuration of the gamma correction device according to the third embodiment.
  • the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a gamma correction value calculation circuit 100 is provided instead of the gamma correction table selection circuit 104 in FIG.
  • the gamma correction value storage circuit 1005 stores the gamma correction table of the reference element and the gamma correction table of each of the other elements as a difference value with respect to the reference element. 5 is provided.
  • the operation will be described. After the input image is captured by the image sensor 101 and the input signal is digitized by the A / D converter 102, the gamma correction is performed by the gamma correction circuit 103 using individual gamma correction values for each device. Do.
  • the gamma correction value is obtained by calculating the gamma correction value of the element selected by the element selection circuit 106 from the gamma correction value stored in the gamma correction value storage means 1005. Calculate in 4.
  • the gamma correction table for each element from the first element to the Nth element is not stored as it is, but the gamma correction table for the element serving as a reference is stored in position.
  • the storage capacity is reduced.
  • Gamma correction is generally performed using gamma correction values for input data stored in ROM in a table format, as shown in Fig. 27. As described above, if this gamma correction table is to be provided for each element, for example, for 6 elements of 8 bits of R, G, and B colors,
  • the gamma correction table of the reference element stores the gamma correction value in the ROM as before, but for the other elements, the difference is stored by storing the difference value of the gamma correction table between the elements adjacent in position. To be smaller.
  • a table 111 shows gamma correction values for each element, and stores gamma correction values for input values of the first to fourth elements.
  • element 1 is the reference element and element 1 is 8-bit gun The correction value is stored.
  • the difference value of the gamma correction value between elements adjacent in position is stored. That is, the difference value is stored for the second element such as a difference value for each input value with the first element, and for the third element, a difference value for each input value with the second element.
  • the difference value of the input value 1 of the second element is the difference value between the second element gamma correction value 18 and the first element gamma correction value 21, the difference value is 1 3 (1 8-2 1 ).
  • the difference value is calculated in this manner, a value as shown in the table 1102 in FIG. 11 is obtained.
  • the difference values in Table 1102 are differences between adjacent pixels, so the difference value is significantly smaller than the original gamma correction value due to the small difference in element characteristics.
  • the value is between 1 and 3. Since storing these numerical values requires only 3 bits, the storage capacity can be reduced to about 3/8.
  • the reference element gamma correction value thus calculated and the difference value are stored in the gamma correction value storage circuit 1005.
  • the difference value is sequentially stored in three bits.
  • the gamma correction table of the gamma correction value storage circuit 1005 has the gamma correction table of the first element and the difference value 1 has the second element.
  • the gamma correction value is sequentially stored as the difference value between the third element and the first element, and the difference value ⁇ 2 as the difference value between the third element and the second element.
  • the gamma correction value calculation circuit 1004 restores the gamma correction value for each element from the reference element gamma correction value and the difference value stored in the gamma correction storage circuit 1005. This restoration method will be described with reference to FIG.
  • the gamma is corrected using the stored gamma correction value.
  • Make corrections For example, when the input image data is 3, gamma correction can be performed by outputting a value 34 corresponding to the input value 3 as output data.
  • the gamma correction value is calculated by adding the value obtained by integrating the difference value up to the element position to the gamma correction value of the reference element, and the gamma correction is performed. For example, number 4 When calculating the gamma correction value corresponding to the input value 0 of the element, the gamma correction value corresponding to the input value 0 of the first element, which is the reference, is 0, and the difference value of the second element is 1, 3, Since the difference value of the element is 11 and the difference value of the fourth element is 2, the value obtained by integrating these values is the gamma correction value. That is,
  • the gamma correction value is calculated. Looking at the table 111 of FIG. 11, it can be seen that the gamma correction value corresponding to the original input value 0 of the fourth element is 2, so that the gamma correction value can be faithfully restored. Similarly, for other elements, a gamma correction value for each element can be calculated by adding a value obtained by integrating the difference value up to the element position to the gamma correction value of the reference element.
  • the gamma correction value calculation circuit 1004 calculates and calculates the gamma correction value for each element selected by the element selection circuit 106 from the reference element gamma correction tape hole and the difference value.
  • Gamma correction can be performed by the gamma correction circuit 103 from the gamma correction value for each element.
  • the difference value between the gamma correction value of the reference element and the gamma correction value of the element adjacent in position is predetermined in the gamma correction storage circuit 1005.
  • Gamma correction is performed using the stored gamma correction value for the reference element, and gamma correction is performed for the other elements by integrating the gamma correction value of the reference element with the differential value up to the element position. Since the gamma correction is performed by calculating the value, the gamma correction can be performed for each pixel, which can suppress the deterioration of the image quality and the gamma correction data for each element with a small storage capacity. Can be memorized.
  • the storage capacity may be changed such that the lower gray scale side stores it as 4 bits and the other gray scales stores it as 2 bits. Good. This is because, as described above, the gamma correction value of the element tends to fluctuate on the low gradation side, so that the difference value becomes large. This is because storage capacity may be wasted. Therefore, as described above, the storage capacity may be changed between the low gradation side and the rest for efficient storage.
  • Embodiment 4 a gamma correction device according to Embodiment 4 of the present invention will be described.
  • This embodiment has a feature in which the configurations of the above-described second embodiment and the third embodiment are combined. That is, in FIG. 12, the same reference numerals as those in FIGS. 4 and 10 indicate the same or corresponding parts, and 1204 indicates the value obtained from the gamma correction value storage circuit 1005.
  • Gamma correction that calculates an appropriate gamma correction value by interpolation using the output of the gamma correction value calculation circuit 104 and the pattern value output from the pattern value storage circuit 408 It is a value interpolation circuit.
  • the gamma correction value storage circuit 1005 stores the gamma correction value for the gray chart pattern, and interpolates the gamma correction value by interpolation. By doing so, it is possible to perform gamma correction with a small storage capacity. That is, the gamma correction value storage circuit 1005 stores the reference element gamma correction table values and the difference values for the number of patterns. 'For example, data as shown in the first 3 (a) view tables are stored. The gamma positive value calculation circuit 1005 calculates the gamma correction value of each element by the method described above. In the case of the table shown in Fig. 13 '(a), element 1 is the reference element, so elements 2 to N are the reference elements. The gamma correction value can be calculated as shown in the table shown in FIG. 13 (b) by adding up the value obtained by integrating the difference values of.
  • the gamma correction value capturing circuit 1204 calculates the gamma correction value from the gamma correction value calculated from the gamma correction value calculation circuit 1005 and the pattern value stored in the pattern value storage circuit 408. Performs interpolation. With regard to this capturing method, interpolation processing is performed according to the method described in the second embodiment.
  • Gamma correction can be performed for each element by the gamma correction circuit 103 based on the gamma correction value interpolated by the gamma correction value interpolation circuit 124 in this manner.
  • the gamma correction storage circuit 1005 stores the gamma correction value of the reference element and the difference value of the gamma correction value of each element stored discretely, The reference element performs gamma correction based on the stored gamma correction value, and the other elements perform gamma correction by calculating an appropriate gamma correction value by interpolation processing in the gamma correction value interpolation circuit 124.
  • Gamma correction for each pixel This makes it possible to suppress deterioration in image quality and to store gamma correction data for each element with a smaller storage capacity.
  • the gamma correction curve has a large change in the low gradation area
  • discrete data is used for the purpose of improving the gamma correction accuracy by taking more data in this area.
  • more gamma correction values for the pattern of the low gradation part that is, the pattern of the area ⁇ ⁇ may be stored.
  • any element may be used as a reference element.
  • any number of reference elements may be provided. Also, the case where the gamma correction value for a discrete input value is stored and the case where 10 patterns of a gray chart are stored has been described, but the number of patterns is not limited to this.
  • interpolation may be performed using a curve such as a 'quadratic curve' instead of performing linear approximation.
  • a gamma correction device according to a fifth embodiment of the present invention will be described with reference to the drawings.
  • the configuration and the basic operation of the gamma correction device according to the fifth embodiment are the same as those described in the third embodiment, except that the gamma correction value storage circuit Rather than storing the difference value of the gamma correction values between elements as it is, if the difference value exceeds the capacity to store the difference value, the next adjacent element adds the excess value to the difference value Is stored as a difference value.
  • the operation will be described in detail.
  • storing the difference value in a predetermined storage capacity greatly simplifies the process of restoring the original gamma correction value.
  • the difference value is larger than the predetermined storage capacity and the storage capacity is exceeded.
  • the gamma correction value is calculated by integrating the difference value as it is, the original gamma correction value cannot be restored.
  • the gamma correction value is In the case where the difference value is stored in 4 bits, the difference value for each element is as shown in Table 1402 in FIG. With 4 bits, values from 8 to 7 cannot be stored.For example, the gamma correction value of element 1 corresponding to input value 1 is 16, the gamma correction value of element 2 is 26, and the difference value is 2. Despite being 10, it exceeds 4 bits and is stored as difference value 7.
  • the gamma correction value corresponding to the input value 1 of the fourth element is 17.
  • the error is added to the next difference value so that the error does not affect the gamma correction value calculation of the next element.
  • the gamma correction value storage circuit 1005 stores the difference value of the gamma correction value between the elements that are adjacent in position, the difference value When the storage capacity is exceeded, the difference value is added to the difference value in the next adjacent element, and the difference value is stored as the difference value.Therefore, gamma correction must be performed for each element with a small storage capacity. When the difference value exceeds the capacity for storing the difference value, the error can be minimized.
  • the gamma correction values for the continuous input data are not stored in the element characteristic correction value table, as described in the second embodiment, but the gamma correction values for the discrete input data are stored.
  • the storage capacity can be further reduced.
  • the gamma correction value for the discrete input value can be stored, the gamma correction value for the low gradation part pattern, that is, the pattern in the dark area is stored more, so that the gamma correction in the low gradation part is stored.
  • Gamma correction accuracy can be improved in a region where the change of the positive curve is large.
  • any element may be used as a reference element.
  • any number of reference elements may be provided.
  • FIG. 16 is a block diagram showing the configuration of the gamma correction device according to the sixth embodiment.
  • the same reference numerals as those in FIG. 1 denote the same or corresponding parts
  • 1604 denotes the average value of the gamma correction values of the elements, and the average value and the gamma correction value of each element.
  • This is a gamma correction value calculation circuit that calculates a gamma correction value based on the value output from the gamma correction value storage circuit 1605 that stores the difference value of.
  • the difference value from the average value of the gamma correction value for each element is stored, It is characterized by performing gamma correction.
  • the gamma correction value storage circuit 1605 calculates and stores the average value of the gamma correction value for each input value and the difference value between the gamma correction value for each element and the average value. For example, if the gamma correction value for each element is as shown in Table 1701 in Fig. 17 (a), the average value and the difference value with respect to the average value are as shown in Fig. 17 (b). It is calculated as shown in Table 1702. For example, when the average value of the gamma correction values of the respective elements with respect to the input value 1 is 21, the gamma correction value of the first element is 16, and the difference value 15 is stored as the difference value.
  • the average value and the difference value are calculated and stored in the gamma correction value storage circuit 1605. Therefore, the average value of each input value is stored in the average value data of the gamma correction value storage circuit 165, and the difference value ⁇ 1 is the difference value of the first element, and the difference value ⁇ 2 is the second element. It is stored as a difference value. By storing the difference value from the average value as the gamma correction value, the storage capacity can be reduced.
  • the element selected by the element selection circuit 1606 from the average value data and the difference value stored in the gamma correction value storage circuit 1605. Calculate the gamma correction value.
  • the first device creates a gamma correction table by adding the difference value ⁇ 1 to the average value data
  • the second device creates a gamma correction table by adding the difference value ⁇ 2 to the average value data. be able to.
  • the average value of the gamma correction values of the elements and the difference value between the average value and the gamma correction value of each element are stored in the gamma correction value storage circuit 1605.
  • the average value of the gamma correction values output from the gamma correction value storage circuit 1605, and the difference between the average value and the gamma correction value of each element The gamma correction value is calculated from the value obtained by adding the difference value for each element to the average value of the gamma correction values for each element using the values and the gamma correction circuit 106.
  • the gamma correction value is calculated by independently adding the difference value to the average value for each element, so that gamma correction can be performed accurately and the difference value of each element is stored independently. Therefore, if the difference value exceeds its storage capacity, the error does not affect the gamma correction of other elements.
  • the gamma correction value storage circuit 1605 does not store the gamma correction values for continuous input data, but instead stores gamma correction values for discrete input values. If the correction value is stored, the storage capacity can be reduced.
  • FIG. 18 is a block diagram showing the configuration of the gamma correction device according to the seventh embodiment.
  • the same reference numerals as those in FIG. 10 denote the same or corresponding parts
  • 1804 denotes a gamma correction value storage circuit 1805 in which the data length of the difference value is stored together.
  • This is a gamma correction value calculation circuit that calculates a gamma correction value by receiving an output.
  • the basic operation is the same as that described in the third embodiment, except that the difference value is not stored in a predetermined storage capacity, but the storage capacity is changed according to the magnitude of the difference value. Are different.
  • the operation will be described in detail.
  • the difference value of the gamma correction value between the elements adjacent in position when the difference value of the gamma correction value between the elements adjacent in position is calculated, the difference value takes various values, so that the difference value is stored in a certain storage capacity. It may be inconvenient to memorize. Therefore, by changing the storage capacity according to the magnitude of the difference value, the difference value can be flexibly stored. At that time, by storing the data length of the difference value together, the gamma correction value can be accurately restored.
  • the difference value of the second element is shown in the table of Fig. 19 (b). It is calculated as shown.
  • the difference value is sequentially recorded as a data length and a difference value as shown in FIG. I will remember. In the case of Fig. 20, the data length is stored in 3 bits, and then the difference value is stored.
  • the data length can be stored in 3 bits by storing the data length as 0 if the difference value is 1 bit, 1 if the difference value is 2 bits, 7 if the difference value is 8 bits, and so on.
  • the difference value of the second element corresponding to the input value 0 is 0, and can be represented by 1 bit, so that the data length is stored as 0.
  • the difference value corresponding to the input value 1 is 10 and can be expressed by 5 bits, the data length is stored as 4.
  • the calculated data length and difference value are sequentially stored as shown in FIG.
  • the difference value can be accurately stored, and the difference value can be adjusted according to the size of the difference value. Can be stored efficiently.
  • the gamma correction value storage circuit 1805 does not store the gamma correction value for the continuous input data, but stores the gamma correction value for the discrete input value. If the information is stored, the storage capacity can be reduced.
  • the gamma correction value can be restored more accurately, so that the accuracy of gamma correction can be improved.
  • FIG. 22 is a block diagram showing a configuration of the gamma correction device according to the eighth embodiment.
  • reference numeral 2204 denotes a gamma correction table selection circuit, which includes an output of a gamma correction table storage circuit 222 composed of a plurality of gamma correction tables, and a gamma correction table corresponding to each element.
  • the predetermined data is selected from the output of the gamma selection value storage circuit 222 in which the number of the gamma is recorded.
  • a plurality of gamma correction tables are prepared in advance, and The storage capacity of the gamma correction value is reduced by selecting a certain gamma correction table.
  • the gamma correction table storage circuit 222 stores N gamma correction tables. A number is assigned to each gamma correction table, a gamma correction table is selected by the number for each element, and gamma correction is performed from the selected gamma correction table.
  • the gamma selection value storage circuit 222 stores a selection number for selecting a gamma correction tape for each element. For example, when the first element selects the gamma correction table 3, the selection number 3 is stored in the gamma selection value storage circuit 222 as the first element table selection number.
  • the gamma correction table selection circuit 222 selects the gamma correction table of the corresponding element from the gamma correction table storage circuit 222 with reference to the selection number of the gamma selection value storage circuit 222. Then, the gamma correction circuit 103 performs gamma correction based on the selected gamma correction table.
  • the overall storage capacity can be reduced. For example, when preparing gamma correction tables for 640 elements, if the gamma correction tables for all elements are prepared individually, the force required for 640 staples Since some devices have gamma characteristics, if 100 gamma correction tables are sufficient, the gamma correction table can be stored with a capacity of 100/6640. In this case, since the capacity of the gamma selection value storage circuit 222 is small, it can be ignored.
  • the gamma selection table (gamma selection value storage circuit 222) is stored in the ROM of the scanner body, and the gamma correction table (gamma correction table storage circuit) is stored in the personal computer. 2 2 0 6).
  • the ROM of the scanner itself has a limited capacity, but when storing it on the personal computer side, a much larger storage capacity can be prepared compared to the ROM of the scanner itself.
  • the ROM capacity of the image scanner can be reduced and more gamma correction tables can be stored.
  • an accurate gamma correction table for each element is calculated, and the table selection number for each element is calculated by comparing the gamma correction table with the gamma correction table prepared in the gamma correction table storage circuit 222 in advance.
  • the gamma correction table can be selected accurately.
  • the gamma correction table storage circuit 2307 stores a reference gamma correction table serving as a reference and a difference value between each gamma correction table and the reference gamma correction table. You may make it. By storing the difference value, the storage capacity of the gamma correction table 2307 can be further reduced.
  • the reference gamma correction table select the gamma correction table with the smallest gamma correction amount. In this case, the gamma correction table is arranged in the order of the smaller gamma correction amount, and the difference value of the gamma correction table is calculated.
  • the difference value ⁇ 1 of the gamma correction table 2307 stores the difference value between the gamma correction table having the second smallest gamma correction amount and the gamma correction table having the smallest gamma correction amount.
  • the difference value ⁇ 2 has a gamma correction table having the third smallest gamma correction amount
  • the difference value with the gamma correction table having the second smallest gamma correction amount is stored.
  • the gamma correction table with the largest gamma correction amount is selected, and when the gamma correction tables are arranged in descending order of the gamma correction amount, the order is adjacent.
  • the difference value of the gamma correction value in the gamma correction table may be stored.
  • the gamma correction value calculation circuit 2306 can calculate the gamma correction table by integrating the difference value with the reference gamma correction table. This is the same as the method described in the third embodiment. For example, if the gamma correction tables are stored in ascending order of the gamma correction amount, the fourth gamma correction table with the smallest gamma correction amount will be the difference value ⁇ 1, difference value ⁇ 2, difference value Value ⁇
  • a plurality of gamma correction tables are stored in the gamma correction table storage circuit 222 in advance, and the gamma correction values are stored in the gamma selection value storage circuit 222 for each element.
  • the selection information of the correction table is stored, and the gamma correction table selection circuit 222 is used to store the gamma correction table corresponding to the tape number stored in the corresponding gamma selection value storage circuit 222.
  • the gamma correction table storage circuit 2307 stores a reference gamma correction table serving as a reference, and a difference value between each gamma correction table and the reference gamma correction table.
  • the storage capacity of the correction table can be further reduced.
  • FIG. 24 is a block diagram showing the configuration of the gamma correction device according to the ninth embodiment.
  • reference numeral 2404 denotes a gamma correction value calculation circuit for calculating a gamma correction value based on a characteristic correction value output from an element characteristic correction value calculation circuit 2405 described later;
  • Reference numeral 5 denotes a characteristic correction of the element selected by adding a value obtained by integrating the difference value up to the element position to a reference element characteristic correction table stored in an element characteristic correction value storage circuit 2406 described later.
  • An element characteristic correction value calculation circuit for calculating a value, and an element characteristic correction value storage circuit 2404 stores an output characteristic correction value corresponding to an input value of the element before performing gamma correction.
  • the basic operation is the same as that of the third embodiment described above. However, instead of storing the gamma correction table, an element characteristic correction value that is an output characteristic correction value for an input value of an element before performing gamma correction is obtained. The difference is that they are stored.
  • the characteristics of the ideal element before gamma correction are linear with respect to the input data, as shown in Fig. 25.
  • JP ⁇ 1 Raw actual elements are offset from the linear characteristic as shown in the second 5 FIG. Therefore, the characteristic correction value for correcting the deviation from the ideal characteristic is stored to correct the characteristic, and a uniform gamma correction process is performed on the corrected characteristic value.
  • the characteristic correction value before gamma correction is stored.
  • the difference value for each element can be reduced as compared with the case where This is the characteristic that when the gamma correction is performed, the characteristics of each element greatly vary in the low-gradation area due to a large change in characteristics.
  • the element characteristics before gamma correction are such that the output value with respect to the input value is almost linear. Therefore, the characteristics do not change significantly, and the difference value for each element can be reduced.
  • the characteristic correction value for each element is as shown in Table 2601 in FIG. 26, and is a value that is almost linear with respect to the input value. Therefore, the difference between the elements adjacent in position is also as shown in Table 260 of FIG. 26, and it is necessary to make the difference smaller than when the difference of the gamma correction value is obtained. Can be.
  • the difference value is a value between 1 and 2 and the difference value can be expressed with 2 bits, so the storage capacity of the gamma correction value can be set to about 2Z8. it can.
  • the element characteristic correction value storage circuit 2406 stores a reference element characteristic correction table that is used as a reference when calculating the original characteristic correction value from the difference value, and a difference value between the characteristic correction values of the elements adjacent in position. Are stored in order.
  • the element characteristic correction table of the first element is stored in the reference element characteristic correction table
  • the difference value ⁇ 1 is the difference value between the element characteristics of the second element and the first element.
  • the difference value ⁇ 2 stores the adjacent difference value such as the difference value of the element characteristics between the third element and the second element with a predetermined storage capacity.
  • the element characteristic correction value calculation circuit 2405 stores the element characteristic correction value of the element selected by the element selection circuit 2407 in the element characteristic correction value storage circuit 2. It is calculated by adding a value obtained by integrating the difference values up to the element position to the reference element characteristic correction table stored in 406.
  • the gamma correction value calculating circuit 2404 compares the gamma correction value corresponding to the output monitor characteristics with the characteristic correction value for each element calculated by the element characteristic correction value calculating circuit 2405. Is calculated.
  • a gamma correction value is calculated so that the reciprocal of the gamma characteristic is 0.45.
  • the gamma correction value for the input value in that case is
  • the gamma correction for each element can be performed with a small storage capacity by storing the element characteristic correction value before the gamma correction.
  • the difference value stores the difference value. If the excess capacity is exceeded, a value obtained by adding the excess value to the difference value may be stored as a difference value in the next adjacent element. By adding the excess value to the difference value of the next element, data can be restored with a minimum error.
  • the element characteristic correction value for each input value is stored.
  • the difference between the characteristic correction value and the average value of each element may be stored. In this way, when the difference value exceeds the storage capacity because the difference value of each element is stored independently, it is possible to prevent the error from affecting the gamma correction of other elements. it can.
  • the difference value of the characteristic correction value between the elements adjacent in position may be stored as the data length and the difference value.
  • the difference value can be stored flexibly, and the element characteristic correction value can be accurately restored by storing the data length of the difference value together.
  • the element characteristic correction value table does not store characteristic correction values for continuous input data from 0 to 255, but rather stores discrete characteristic values. Characteristic correction values for various input data may be stored.
  • element characteristic values corresponding to discrete input values are stored, as described in Embodiment 2, accuracy is improved by storing more data in a low gradation area, that is, in a dark area. Can be done.
  • the first element is used as a reference element as a reference element. However, any element may be used as a reference element. Furthermore, instead of having only one reference element, any number of reference elements may be provided. Industrial applicability
  • a gamma correction device includes a gamma correction value storage unit that stores a gamma correction value for each image sensor, and performs a gamma correction process in which a gamma correction value is selected for each element, thereby achieving high accuracy.
  • Gamma correction to provide an image with little image quality degradation.

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Abstract

A gamma correction device capable of reducing the storage capacity of a gamma correction value irrespective of the size of input data. A gamma correction value for discrete input data is stored in a gamma correction value storage circuit (105) so that a proper gamma correction value is calculated to complete a gamma correction by an interpolation at a gamma correction value interpolation circuit (404) by using the pattern value containing applicable input data from a pattern value storage circuit (408) storing with the discrete degree of the input data and the gamma correction value stored in the gamma correction value storage circuit (105).

Description

明 細 書 ガンマ補正装置 技術分野  Description Gamma correction device Technical field
本発明はガンマ補正装置に関し、 特に撮像装置としてイメージスキャナを用い る場合のガンマ捕正に関するものである。 背景技術  The present invention relates to a gamma correction device, and more particularly to gamma correction when an image scanner is used as an imaging device. Background art
従来のイメージスキャナにおいて、 取り込んだ画像を表示するモニタ等の表示 装置との間で、 入力信号に対する出力信号の線形性を保っためにガンマ捕正が行 われる。 一般的には表示装置であるモニタはガンマ = 2 . 2の特性を持っため、 イメージスキャナ側では、 ガンマ: = 0 . 4 5となるようにガンマ捕正を行い、 入 力信号に対する出力信号の特性がリニアになるようにガンマ補正を行う。  In a conventional image scanner, gamma correction is performed with a display device such as a monitor for displaying a captured image in order to maintain the linearity of an output signal with respect to an input signal. In general, a monitor, which is a display device, has a characteristic of gamma = 2.2, so the image scanner performs gamma correction so that gamma: = 0.445, and outputs the output signal with respect to the input signal. Gamma correction is performed so that the characteristics become linear.
実際のガンマ補正は第 2 7図に示すように、 入力信号に対するガンマ捕正値を 予め算出してガンマ補正テーブルを R OMに格納しておき、 入力信号によって R OMのァドレスを参照し、 そのァドレスに格納されているガンマ捕正データを出 力信号として出力することにより実現することができる。  In actual gamma correction, as shown in Fig. 27, the gamma correction value for the input signal is calculated in advance, the gamma correction table is stored in ROM, and the address of ROM is referred to by the input signal. This can be realized by outputting the gamma correction data stored in the address as an output signal.
このガンマ特性はイメージスキャナの素子毎に異なるが、 ほとんどのイメージ スキャナでは 1個のガンマ補正値でしかガンマ補正を行わないため、 素子毎のガ ンマ特性の差により読み取り画像に色むらが生じたり、 すじが入ったりするなど の画質劣化が生じていた。  This gamma characteristic differs for each element of the image scanner.However, most image scanners perform gamma correction with only one gamma correction value, and color differences may occur in scanned images due to differences in gamma characteristics for each element. Image quality degradation such as streaks and streaks has occurred.
そして、 従来、 この素子特性のばらつきをおさえるために、 シェーディング補 正が行われている。 このシェーディング補正では、 素子毎の黒レベルと白レベル とを補正することで素子の特性のばらつきを抑えることができる。しかしながら、 中間階調では、 やはり特 1"生のばらつきが生じるため画質劣化が生じていた。  Conventionally, shading correction has been performed to suppress the variation in the element characteristics. In this shading correction, variations in element characteristics can be suppressed by correcting the black level and white level of each element. However, in the case of the intermediate gradation, the image quality was degraded due to the characteristic variation of “1”.
さらに、 上記ガンマ補正を行うために必要なガンマ捕正テーブルの記憶容量を 減らす方法として、素子毎のガンマ捕正テ一プルの容量を減らす目的ではないが、 数種類のガンマ補正テーブルを機器に持たせる場合に捕正テーブル容量を減らす 方法として、 例えば、 特開平 8—1 9 5 8 9 5号公報に示される、 ディジタルガ ンマ補正方法及びその装置がある。 Furthermore, as a method of reducing the storage capacity of the gamma correction table necessary for performing the above gamma correction, the purpose of the method is not to reduce the capacity of the gamma correction table for each element, but the device has several types of gamma correction tables. To reduce the size of the collection table As a method, there is, for example, a digital gamma correction method and an apparatus thereof disclosed in Japanese Patent Application Laid-Open No. 8-195895.
以下に、 この従来例について詳しく説明する。  Hereinafter, this conventional example will be described in detail.
第 2 8図は、 従来のガンマ補正を行う装置を示すブロック図である。 第 2 8図 において、 2 8 0 1はデータが入力される入力端、 2 8 0 2は入力端 2 8 0 1力、 らの信号と後述するマイク口プロセッサの出力とを切り替えて出力する入力選択 部、 2 8 0 3は入力選択部 2 8 0 2から出力される信号を処理するガンマ特性捕 正部、 2 8 0 4は特性選択部、 2 8 0 5は特性選択部 2 8 0 4の出力を受けるマ イク口プロセッサ、 2 8 0 6は上記マイクロプロセッサ 2 8 0 5へデータを供給 するデータ貯蔵部である。 また、 2 8 0 6 ( 1 ) 〜2 8 0 6 (M) は上記データ 貯蔵部 2 8 0 6を構成するメモリを示している。  FIG. 28 is a block diagram showing a conventional device for performing gamma correction. In FIG. 28, 280 1 is an input terminal to which data is input, 280 2 is an input terminal 280 1, and an input for switching between a signal from the input terminal 280 1 and an output of a microphone port processor to be described later. The selection section, 2803 is a gamma characteristic correction section that processes the signal output from the input selection section 2802, 284 is the characteristic selection section, 2805 is the characteristic selection section 28004 The microprocessor 28006 that receives the output of the microprocessor 280 is a data storage unit that supplies data to the microprocessor 285. Reference numerals 280 (1) to 280 (M) denote memories constituting the data storage unit 2806.
上記データ貯蔵部 2 8 0 6には、 M個のガンマ補正テーブルのデータが保存さ れており、 各ガンマ補正テーブルは一つの基準データと複数個の差分値とを保存 している。 特性選択部 2 8 0 4から供給されるガンマ特性選択信号により、 マイ クロプロセッサ 2 8 0 5がデータ貯蔵部 2 8 0 6から選択されたガンマ特性に応 じたメモリから貯蔵されている基準データ、 及び複数個の差分値を読み出す。 マ イク口プロセッサ 2 8 0 5は読み出された基準データ及び、 複数個の差分値を用 いてガンマ特性テ一ブルを復元し、 ガンマ特性補正部 2 8 0 3にルックアップテ 一ブル形態で保存する。 そして、 ガンマ特性補正部 2 8 0 3では、 入力された映 像データをアドレスデータとして、 そのア レスに対応するガンマ捕正値を出力 することでガンマ捕正が行われる。  The data storage unit 2806 stores data of M gamma correction tables, and each gamma correction table stores one reference data and a plurality of difference values. Based on the gamma characteristic selection signal supplied from the characteristic selection unit 284, the microprocessor 285 selects reference data stored from the memory corresponding to the gamma characteristic selected from the data storage unit 286. , And a plurality of difference values are read. The microphone processor 28005 restores the gamma characteristic table using the read reference data and a plurality of difference values, and the gamma characteristic correction section 2803 uses a look-up table form. save. Then, the gamma characteristic correction unit 2803 performs gamma correction by using the input video data as address data and outputting a gamma correction value corresponding to the address.
上記データ貯蔵部 2 8 0 6には、 ガンマ補正テーブルをそのまま記憶させるの ではなく、 基準データと複数個の差分値とを記憶することで記憶容量の削減を行 つている。 例えば、 ガンマ特性が第 2 9図に示すような場合、 データ貯蔵部 2 8 0 6には、 入力データ X ( 1 ) に対応するガンマ補正値 G ( 1 ) を基準データに 記憶させ、 残りのガンマ補正値は、  In the data storage unit 286, instead of storing the gamma correction table as it is, the storage capacity is reduced by storing the reference data and a plurality of difference values. For example, when the gamma characteristic is as shown in FIG. 29, the data storage unit 286 stores the gamma correction value G (1) corresponding to the input data X (1) as the reference data, and stores the remaining data. The gamma correction value is
D G ( k ) = G ( k ) 一 G ( k— 1 ) D G (k) = G (k) one G (k— 1)
の関係を有する差分値 D G ( k ) の形態で記憶する。 すなわち隣接する入力値に 対するガンマ捕正値の差分値を算出して記憶するようにする。 基準データと差分値からガンマ補正データを復元するには、 基準データから k 番目までの差分値を積算することにより復元することができる。 このように基準 データ以外は差分値となるため記憶容量を小さくすることができる。 Is stored in the form of a difference value DG (k) having the relationship That is, the difference value between the gamma correction values for adjacent input values is calculated and stored. To restore the gamma correction data from the reference data and the difference value, the gamma correction data can be restored by integrating the k-th difference value from the reference data. As described above, since the values other than the reference data are difference values, the storage capacity can be reduced.
しかしながら、 従来のガンマ補正装置では、 低階調領域、 すなわち入力データ の値が小さい領域では、 ガンマ特性の変化量が大きくなるため、 記憶容量が小さ くならないという問題があった。 例えば、 ある素子のガンマ補正データが第 3 0 ( a ) 図に示すようなガンマ捕正特性であった場合、 入力データに対するガンマ 捕正値は第 3 0 ( b ) 図に示すようになる。 ここで入力データ 1に対応するガン マ補正値 5を基準データとした場合、 入力データ 2に対応する差分値は、 2 2 - 5 = 1 7  However, the conventional gamma correction device has a problem that the storage capacity does not decrease in the low gradation region, that is, in the region where the value of the input data is small, because the amount of change in the gamma characteristic is large. For example, if the gamma correction data of a certain element has the gamma correction characteristic as shown in FIG. 30 (a), the gamma correction value for the input data is as shown in FIG. 30 (b). If the gamma correction value 5 corresponding to input data 1 is used as reference data, the difference value corresponding to input data 2 is 2 2-5 = 1 7
となる。 同様に入力データ 3に対応する差分値は 1 2、 入力データ 4に対応する 差分値は 6となる。 差分値を記憶するための容量は差分値の最大値を記憶できる ようにしなければならないので、 この場合、 1 7を記憶するために 5ビットの記 憶容量が必要となる。 このように入力データが小さい領域では素子のガンマ特性 によって差分値が小さくならず、 ガンマ補正値の記憶容量を小さくできない場合 力 Sあつた。 Becomes Similarly, the difference value corresponding to input data 3 is 1 2 and the difference value corresponding to input data 4 is 6. The capacity for storing the difference value must be such that the maximum value of the difference value can be stored. In this case, a storage capacity of 5 bits is required to store 17. In this way, when the input data is small, the difference value does not decrease due to the gamma characteristic of the element, and the storage capacity of the gamma correction value cannot be reduced.
また、 従来のガンマ捕正装置は、 素子毎に異なるガンマ補正値でガンマ補正を 行うものでなく、 素子毎に同一のガンマ補正値でガンマ補正を行うものであるた め、 素子毎に同一のガンマ捕正テーブルを複数用意してガンマ捕正を行うことは できるものの、 素子毎に異なるガンマ補正を行うことはできなかった。  In addition, the conventional gamma correction device does not perform gamma correction with a different gamma correction value for each element, but performs gamma correction with the same gamma correction value for each element. Although gamma correction could be performed by preparing multiple gamma correction tables, different gamma corrections could not be performed for each element.
従来のガンマ補正装置は以上のように構成されており、 素子毎に同一のガンマ 補正テ一ブルを複数用意してガンマ補正を行うために十分に画質劣化を防止でき るものではなかった。  The conventional gamma correction device is configured as described above, and the same gamma correction table is prepared for each element, and the gamma correction is performed, so that the image quality deterioration cannot be sufficiently prevented.
また、 入力データが小さレ、領域では素子のガンマ特性によつて差分値が小さく ならず、 ガンマ捕正値の記憶容量を効率的に低減することができないという問題 点があった。  In addition, in a small input data area, the difference value does not become small due to the gamma characteristic of the element, and the storage capacity of the gamma correction value cannot be reduced efficiently.
この発明は以上のような問題点を解消するためになされたもので、 高精度なガ The present invention has been made in order to solve the above problems, and has a high precision
'補正を行うことができるガンマ補正装置を提供することを目的とする。 また、 入力データの大きさに関わらず、 ガンマ補正値の記憶容量を小さいもの とすることができるガンマ補正装置を提供することを目的とする。 発明の開示 'To provide a gamma correction device capable of performing correction. In addition, regardless of the size of the input data, the storage capacity of the gamma correction value is small. It is an object of the present invention to provide a gamma correction device capable of: Disclosure of the invention
本発明の請求の範囲第 1項にかかるガンマ補正装置は、 複数の撮像素子のガン マ特性を捕正するガンマ捕正装置において、 すべての撮像素子のガンマ捕正値を 記憶するガンマ補正値記憶手段と、 上記ガンマ捕正値記憶手段から素子毎のガン マ補正値を選択するガンマ補正値選択手段と、 上記ガンマ補正値選択手段によつ て選択されたガンマ捕正値を用いて素子毎に個別のガンマ捕正を行うガンマ捕正 手段とを備えたものである。  A gamma correction device according to claim 1 of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of image sensors, wherein a gamma correction value storage for storing gamma correction values of all image sensors. Means, a gamma correction value selecting means for selecting a gamma correction value for each element from the gamma correction value storage means, and a gamma correction value selected by the gamma correction value selecting means for each element. Gamma correction means for individually performing gamma correction.
また、本発明の請求の範囲第 2項にかかるガンマ補正装置は、上記請求の範囲第 1項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定の画像 を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記ガンマ 補正値記憶手段に記憶してある所定の画像の入力値とガンマ捕正値とから補間処 理を行い、 素子毎のガンマ補正値を算出するガンマ補正値補間手段を備えたもの である。  The gamma correction device according to claim 2 of the present invention is the gamma correction device according to claim 1, wherein the gamma correction value storage means includes a discrete input device that reads a predetermined image. A gamma correction value for each element is stored, and an interpolation process is performed from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means to calculate a gamma correction value for each element. It has gamma correction value interpolation means.
また、 本発明の請求の範囲第 3項にかかるガンマ捕正装置は、 上記請求の範囲 第 1項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定の画 像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階調部 のガンマ補正値をより多く記憶するものである。  Further, the gamma correction device according to claim 3 of the present invention is the gamma correction device according to claim 1, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image. When storing a gamma correction value for an appropriate input value, the gamma correction value for a low gradation part is stored more.
また、 本発明の請求の範囲第 4項にかかるガンマ補正装置は、 複数の撮像素子 のガンマ特性を捕正するガンマ補正装置において、 基準素子のガンマ補正値と、 それぞれ位置的に隣接する素子どうしのガンマ補正値の差分値とを、 予め定めた 記憶容量で記憶するガンマ補正値記憶手段と、 基準素子は記憶してあるガンマ捕 正値を用い、 それ以外の素子では、 基準素子のガンマ補正値に当該素子の位置ま でに存在する素子の差分値をそれぞれ積算することで、 素子毎のガンマ補正値を 算出するガンマ捕正値算出手段と、 上記算出したガンマ捕正 ί直から素子毎にガン マ補正を行うガンマ補正手段とを備えたものである。  Further, a gamma correction device according to claim 4 of the present invention is a gamma correction device for capturing gamma characteristics of a plurality of imaging devices, wherein the gamma correction value of the reference device and each of the devices that are positionally adjacent to each other. Gamma correction value storage means for storing the difference value of the gamma correction values of the above with a predetermined storage capacity, the reference element uses the stored gamma correction value, and the other elements use the gamma correction of the reference element. Gamma correction value calculation means for calculating a gamma correction value for each element by integrating the difference value of the element existing up to the position of the element with the value, and a gamma correction value calculated from the above calculated gamma correction value for each element. In addition, gamma correction means for performing gamma correction is provided.
また、 本発明の請求の範囲第 5項にかかるガンマ補正装置は、 上記請求の範囲 第 4項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定の画 像を読み取った離散的な入力値に対するガンマ捕正値を記憶しており、 上記ガン マ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値とから補間 処理を行い、 素子毎のガンマ補正値を算出するガンマ捕正値補間手段を備えたも のである。 The gamma correction device according to claim 5 of the present invention is the gamma correction device according to claim 4, wherein the gamma correction value storage means includes a predetermined image. A gamma correction value corresponding to a discrete input value obtained by reading an image is stored, and an interpolation process is performed based on the input value and the gamma correction value of a predetermined image stored in the gamma correction value storage unit. The gamma correction value interpolation means for calculating the gamma correction value for each is provided.
また、 本発明の請求の範囲第 6項にかかるガンマ捕正装置は、 上記請求の範囲 第 4項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定の画 像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階調部 のガンマ補正値をより多く記憶するものである。  The gamma correction device according to claim 6 of the present invention is the gamma correction device according to claim 4, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image. When storing a gamma correction value for an appropriate input value, the gamma correction value for a low gradation part is stored more.
また、 本発明の請求の範囲第 7項にかかるガンマ補正装置は、 複数の撮像素子 のガンマ特性を捕正するガンマ補正装置において、 基準素子のガンマ補正値と、 それぞれ位置的に隣接する素子どうしのガンマ補正値の差分値とを、 予め定めた 記憶容量で記憶し、 上記差分値が予め定めた記憶容量を超過した場合、 隣接する 素子では該差分値に上記予め定めた記憶容量を超過した値を加算して記憶するガ ンマ捕正値記憶手段と、 基準素子は記憶してあるガンマ捕正値を用い、 それ以外 の素子では、 基準素子のガンマ補正値に当該素子の位置までに存在する素子の差 分値をそれぞれ積算することで、 素子毎のガンマ補正値を算出するガンマ補正値 算出手段と、 上記算出したガンマ補正値から素子毎にガンマ補正を行うガンマ補 正手段とを備えたものである。  A gamma correction device according to claim 7 of the present invention is a gamma correction device for capturing gamma characteristics of a plurality of image pickup devices, wherein a gamma correction value of a reference device and a device that is each positionally adjacent to each other. The difference value of the gamma correction value of the above is stored in a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, the adjacent element exceeds the predetermined storage capacity by the difference value. The gamma correction value storage means that adds and stores the value, and the reference element uses the stored gamma correction value, and the other elements use the gamma correction value of the reference element up to the position of the element. Gamma correction value calculating means for calculating a gamma correction value for each element by integrating the differential values of the elements to be corrected, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. It is provided with.
また、 本発明の請求の範囲第 8項にかかるガンマ補正装置は、 上記請求の範囲 第 7項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定の画 像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記ガン マ捕正値記憶手段に記憶してある所定の画像の入力値とガンマ捕正値とから補間 処理を行い、 素子毎のガンマ捕正値を算出するガンマ補正値捕間手段を備えたも のである。  The gamma correction device according to claim 8 of the present invention is the gamma correction device according to claim 7, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image. The gamma correction value for the input value is stored. The gamma correction value is interpolated from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means, and the gamma correction value for each element is obtained. It is provided with a gamma correction value capturing means for calculating the gamma correction value.
また、 本発明の請求の範囲第 9項にかかるガンマ捕正装置は、 上記請求の範囲 第 7項記載のガンマ捕正装置において、 上記ガンマ補正値記憶手段は、 所定の画 像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階調部 のガンマ補正値をより多く記憶するものである。  The gamma correction device according to claim 9 of the present invention is the gamma correction device according to claim 7, wherein the gamma correction value storage means is configured to read a predetermined image. When storing the gamma correction value for a typical input value, the gamma correction value for the low gradation part is stored more.
また、 本発明の請求の範囲第 1 0項にかかるガンマ補正装置は、 複数の撮像素 子のガンマ特 1·生を補正するガンマ捕正装置において、 入力値毎の各素子のガンマ 補正値の平均値と、 該平均値と上記各素子毎のガンマ補正値との差分値を記憶し たガンマ補正値記憶手段と、 素子毎のガンマ補正値を、 上記ガンマ補正値の平均 値に、 素子毎の差分値を加算して算出するガンマ補正値算出手段と、 上記算出し たガンマ補正値から素子毎にガンマ補正を行うガンマ捕正手段とを備えたもので ある。 Further, the gamma correction device according to claim 10 of the present invention includes a plurality of imaging elements. In a gamma correction device that corrects the gamma characteristic of a child, the average value of the gamma correction value of each element for each input value and the difference value between the average value and the gamma correction value of each element are stored. Gamma correction value storage means, gamma correction value calculation means for calculating the gamma correction value for each element by adding the difference value for each element to the average value of the gamma correction values, and gamma correction value calculated above And gamma correction means for performing gamma correction for each element.
また、 本発明の請求の範囲第 1 1項にかかるガンマ補正装置は、 上記請求の範 囲第 1 0項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記 ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値とから 捕間処理を行い、 素子毎のガンマ捕正値を算出するガンマ補正値捕間手段を備え たものである。  The gamma correction device according to claim 11 of the present invention is the gamma correction device according to claim 10, wherein the gamma correction value storage means reads a predetermined image from a discrete image. A gamma correction value corresponding to a typical input value is stored. A gamma correction value is calculated from the input value of the predetermined image stored in the gamma correction value storage means and the gamma correction value. It is provided with a gamma correction value capturing means for calculating the gamma correction value.
また、 本発明の請求の範囲第 1 2項にかかるガンマ捕正装置は、 上記請求の範 囲第 1 0項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階 調部のガンマ補正値をより多く記憶するものである。  The gamma correction device according to claim 12 of the present invention is the gamma correction device according to claim 10, wherein the gamma correction value storage means reads a predetermined image. When storing gamma correction values for discrete input values, the gamma correction values for the low-tone portion are stored more.
また、 本発明の請求の範囲第 1 3項にかかるガンマ補正装置は、 複数の撮像素 子のガンマ特^ ·生を補正するガンマ補正装置において、基準素子のガンマ補正値と、 それぞれ位置的に隣接する素子どうしのガンマ補正値との差分値と、 該差分値の データ長を記億するガンマ補正値記憶手段と、 基準素子は記憶してあるガンマ捕 正値によりガンマ捕正を行い、 それ以外の素子では基準素子のガンマ捕正値に当 該素子の位置までに存在する素子の差分値をそれぞれ積算することで、 素子毎の ガンマ捕正値を算出するガンマ補正値算出手段と、 上記算出したガンマ捕正値か ら素子毎にガンマ補正を行うガンマ捕正手段とを備えたものである。  Further, a gamma correction device according to claim 13 of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, wherein the gamma correction value of a reference element and a gamma correction value of a reference element are each different. A gamma correction value storing means for storing a difference value between a gamma correction value between adjacent elements and a data length of the difference value; a reference element performs gamma correction by using a stored gamma correction value; For other elements, a gamma correction value calculating means for calculating a gamma correction value for each element by integrating a difference value of an element existing up to the position of the element with a gamma correction value of the reference element. Gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
また、 本発明の請求の範囲第 1 4項にかかるガンマ補正装置は、 上記請求の範 囲第 1 3項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記 ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ捕正値とから 補間処理を行い、 素子毎のガンマ補正値を算出するガンマ補正値捕間手段を備え たものである。 The gamma correction device according to claim 14 of the present invention is the gamma correction device according to claim 13, wherein the gamma correction value storage means reads a predetermined image from a discrete image. A gamma correction value corresponding to a typical input value is stored, an interpolation process is performed from the input value of a predetermined image stored in the gamma correction value storage means and a gamma correction value, and a gamma correction value for each element is calculated. Equipped with gamma correction value capture means to calculate It is a thing.
また、 本発明の請求の範囲第 1 5項にかかるガンマ補正装置は、 上記請求の範 囲第 1 3項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階 調部のガンマ補正値をより多く記憶するものである。  The gamma correction device according to claim 15 of the present invention is the gamma correction device according to claim 13, wherein the gamma correction value storage means is a discrete gamma correction device that reads a predetermined image. When the gamma correction value for a typical input value is stored, the gamma correction value for the low gradation part is stored more.
また、 本発明の請求の範囲第 1 6項にかかるガンマ捕正装置は、 複数の撮像素 子のガンマ特性を補正するガンマ補正装置において、 複数のガンマ補正テーブル を記憶するガンマ補正テーブル記憶手段と、 素子毎にガンマ補正テーブルを選択 するための選択情報を記憶するガンマ捕正テーブル選択情報記憶手段と、 上記ガ ンマ捕正テーブル記憶手段と上記ガンマ捕正テーブル選択情報記憶手段と力ゝら素 子毎に対応したガンマ補正テーブルを選択するガンマ補正テーブル選択手段と、 選択したガンマ捕正テーブルによりガンマ補正を行うガンマ補正手段とを備えた ものである。  Further, a gamma correction device according to claim 16 of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, wherein the gamma correction table storage means stores a plurality of gamma correction tables. Gamma correction table selection information storage means for storing selection information for selecting a gamma correction table for each element; gamma correction table storage means; gamma correction table selection information storage means; A gamma correction table selecting means for selecting a gamma correction table corresponding to each child, and a gamma correction means for performing gamma correction based on the selected gamma correction table.
また、 本発明の請求の範囲第 1 7項にかかるガンマ捕正装置は、 上記請求の範 囲第 1 6項記載のガンマ捕正装置において、上記ガンマ補正テーブル記憶手段は、 ガンマ捕正量が最も小さいガンマ補正テーブル、 あるいはガンマ捕正量が最も大 きいガンマ補正テーブルを基準のガンマ補正テーブルとして記憶し、 その他のガ ンマ補正テーブルは、 基準のガンマ補正テーブルがガンマ補正量の最も小さいガ ンマ捕正テーブルを用いる場合は、 ガンマ補正量が小さい順番にガンマ補正テー ブルを並べた場合に順番が隣り合うガンマ補正値の差分値を記憶し、 一方、 基準 のガンマ補正テーブルとしてガンマ捕正量の最も大きいガンマ補正テ一ブルを用 いる場合は、 ガンマ補正量が大きい順番にガンマ補正テープノレを並べた場合に順 番が隣り合うガンマ捕正値の差分値を記憶し、 上記基準のガンマ捕正テーブルと 差分値とからガンマ補正テーブルを算出するガンマ補正テーブル算出手段を備え たものである。  Further, the gamma correction device according to claim 17 of the present invention is the gamma correction device according to claim 16, wherein the gamma correction table storage means has a gamma correction amount. The gamma correction table with the smallest gamma correction amount or the gamma correction amount with the largest gamma correction amount is stored as the reference gamma correction table, and the other gamma correction tables are those whose reference gamma correction table has the smallest gamma correction amount. When the correction table is used, when the gamma correction tables are arranged in ascending order of the gamma correction amount, the difference value of the adjacent gamma correction values is stored.On the other hand, the gamma correction amount is used as a reference gamma correction table. When the gamma correction table with the largest gamma correction amount is used, the gamma correction tape Storing the difference value meets gamma ToTadashichi, those having a gamma correction table calculating means for calculating the gamma correction table and a gamma capturing positive table and the difference value of the reference.
また、 本発明の請求の範囲第 1 8項にかかるガンマ補正装置は、 上記請求の範 囲第 1 6項記載のガンマ補正装置において、上記ガンマ補正テーブル選択手段は、 素子のガンマ補正テーブルと、 ガンマ捕正テーブル記憶手段に記憶してある複数 のガンマ補正テーブルとで、 ガンマ補正値の最小二乗和が最も小さくなるガンマ 捕正テ一ブルを選択するものである。 The gamma correction device according to claim 18 of the present invention is the gamma correction device according to claim 16, wherein the gamma correction table selection means includes: The gamma that minimizes the least square sum of the gamma correction values with a plurality of gamma correction tables stored in the gamma correction table storage means This is to select a capture table.
また、 本発明の請求の範囲第 1 9項にかかるガンマ補正装置は、 複数の撮像素 子のガンマ特性を補正するガンマ補正装置において、 ガンマ補正前の基準素子の 入力値に対する出力特性補正値である素子特性補正値と、 それぞれ位置的に隣接 する素子どうしにおける、 ガンマ補正前の入力値に対する出力特性補正値である 素子特性補正値の差分値とを、 予め定めた記憶容量で記憶する素子特性捕正値記 憶手段と、基準素子は記憶してある素子特性補正値によりガンマ補正値を算出し、 それ以外の素子では、 基準素子の素子特性捕正値に該素子の位置までに存在する 素子の差分値をそれぞれ積算することで、 素子毎のガンマ補正値を算出する素子 特 1·生補正値算出手段と、 上記算出した素子毎の特性補正値から素子毎にガンマ捕 正値を算出するガンマ補正値算出手段と、 上記算出したガンマ補正値から素子毎 にガンマ補正を行うガンマ捕正手段とを備えたものである。  A gamma correction apparatus according to claim 19 of the present invention is a gamma correction apparatus for correcting gamma characteristics of a plurality of imaging elements, wherein the gamma correction apparatus outputs an output characteristic correction value for an input value of a reference element before gamma correction. An element characteristic that stores a certain element characteristic correction value and a difference value of an element characteristic correction value, which is an output characteristic correction value with respect to an input value before gamma correction, between elements adjacent in position with a predetermined storage capacity. The correction value storage means and the reference element calculate a gamma correction value based on the stored element characteristic correction value, and the other elements exist in the element characteristic correction value of the reference element up to the position of the element. An element characteristic calculation means for calculating a gamma correction value for each element by integrating the element difference values, and a gamma correction value for each element based on the calculated characteristic correction value for each element. A calculating gamma correction value calculating means, in which a gamma ToTadashi means for performing gamma correction for each element from the gamma correction value calculated above.
また、 本発明の請求の範囲第 2 0項にかかるガンマ補正装置は、 上記請求の範 囲第 1 9項記載のガンマ補正装置において、 上記素子特性記憶手段は、 位置的に 隣接する素子どうしの素子特性補正値の差分値を予め定めた記憶容量で記憶し、 差分値が予め定めた記憶容量を超過した場合、 隣接する素子では差分値に超過し た値を加算して記憶するものである。  The gamma correction device according to claim 20 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic storage means is configured to determine a position between adjacent elements in position. The difference value of the element characteristic correction value is stored in a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, an adjacent element adds and stores the excess value to the difference value. .
また、 本発明の請求の範囲第 2 1項にかかるガンマ補正装置は、 上記請求の範 囲第 1 9項記載のガンマ補正装置において、 上記素子特性補正値記憶手段は、 素 子の素子特性補正値の平均値と、 その平均値と各素子毎の素子特性補正値の差分 値とを記憶し、 上記素子特性補正値算出手段は、 各素子毎の素子特性捕正値の平 均値に素子毎の差分値を加算した値から素子特性補正値を算出するものである。 また、 本発明の請求の範囲第 2 2項にかかるガンマ補正装置は、 上記請求の範 囲第 1 9項記載のガンマ補正装置において、 上記素子特†生記憶手段は、 位置的に 隣接する素子どうしの素子特性補正値の差分値をそのデータ長と共に記憶するも のである。  The gamma correction device according to claim 21 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic correction value storage means is configured to correct element characteristic correction of the element. The average value of the values and a difference value between the average value and the element characteristic correction value for each element are stored, and the element characteristic correction value calculating means converts the element value into an average value of the element characteristic correction value for each element. The element characteristic correction value is calculated from the value obtained by adding the difference value for each element. Further, the gamma correction device according to claim 22 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic storage means is a device which is positioned adjacent to the device. The difference between the element characteristic correction values is stored together with the data length.
また、 本発明の請求の範囲第 2 3項にかかるガンマ捕正装置は、 上記請求の範 囲第 1 9項記載のガンマ補正装置において、 上記素子特性捕正値記憶手段は、 所 定の画像を読み取った離散的な入力値に対する素子特性補正値を記憶し、 上記素 子特性補正値補間手段は、 上記素子特性捕正値記憶手段に記憶してある所定の画 像の入力値と素子特性捕正値とから補間処理を行って素子毎の素子特性補正値を 算出するものである。 The gamma correction device according to claim 23 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic correction value storage means is configured to store a predetermined image. The element characteristic correction value for the discrete input value obtained by reading The element characteristic correction value interpolation means calculates an element characteristic correction value for each element by performing an interpolation process from the input value of the predetermined image and the element characteristic correction value stored in the element characteristic correction value storage means. Is what you do.
また、 本発明の請求の範囲第 2 4項にかかるガンマ捕正装置は、 上記請求の範 囲第 1 9項記載のガンマ補正装置において、 上記素子特性補正値記憶手段は、 所 定の画像を読み取った離散的な入力値に対する素子特性補正値を記憶させる際に、 低階調部の素子特性捕正値をより多く記憶させるものである。  The gamma correction device according to claim 24 of the present invention is the gamma correction device according to claim 19, wherein the element characteristic correction value storage means stores a predetermined image. When storing the element characteristic correction value for the read discrete input value, the element characteristic correction value of the low gradation part is stored more.
以上のように、 本発明の請求の範囲第 1項に係るガンマ補正装置によれば、 複 数の撮像素子のガンマ特性を補正するガンマ補正装置において、 すべての撮像素 子のガンマ補正値を記憶するガンマ補正値記憶手段と、 上記ガンマ補正値記憶手 段から素子毎のガンマ補正値を選択するガンマ補正値選択手段と、 上記ガンマ捕 正値選択手段によって選択されたガンマ補正値を用いて素子毎に個別のガンマ捕 正を行うガンマ補正手段とを備えたものとしたので、 素子毎にガンマ補正を行う ことにより素子のガンマ特性を捕正でき、 より高精度なガンマ捕正を行うことが できるという効果が得られる。  As described above, according to the gamma correction device according to claim 1 of the present invention, a gamma correction device that corrects the gamma characteristics of a plurality of imaging devices stores gamma correction values of all imaging devices. Gamma correction value storage means, gamma correction value selection means for selecting a gamma correction value for each element from the gamma correction value storage means, and an element using the gamma correction value selected by the gamma correction value selection means. A gamma correction unit that performs gamma correction individually for each device is provided.By performing gamma correction for each device, the gamma characteristics of the device can be corrected, and more accurate gamma correction can be performed. The effect that it can be obtained is obtained.
また、 本発明の請求の範囲第 2項に係るガンマ捕正装置によれば、 上記請求の 範囲第 1項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記 ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値とから 補間処理を行い、 素子毎のガンマ補正値を算出するガンマ捕正値捕間手段を備え たものとしたので、 離散的な入力値に対するガンマ補正値のみを記憶させること で、 少ない記憶容量で素子毎にガンマ補正を行うことができるという効果が得ら れる。  Further, according to the gamma correction device according to claim 2 of the present invention, in the gamma correction device according to claim 1, the gamma correction value storage means includes a discrete image read from a predetermined image. A gamma correction value for a specific input value is stored, and an interpolation process is performed based on the input value and the gamma correction value of a predetermined image stored in the gamma correction value storage means to calculate a gamma correction value for each element. Since gamma correction value capturing means is provided, only gamma correction values for discrete input values are stored, so that gamma correction can be performed for each element with a small storage capacity. Is received.
また、 本発明の請求の範囲第 3項に係るガンマ補正装置によれば、 上記請求の 範囲第 1項記載のガンマ補正装置において、 上記請求の範囲第 1項記載のガンマ 補正装置において、 上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散 的な入力値に対するガンマ補正値を記憶する際に、 低階調部のガンマ補正値をよ り多く記憶するようにしたので、 変化量の大きい低階調部のガンマ補正値をより 多く記憶させることで少なレ、記憶容量で、 しかも精度よく素子毎にガンマ補正を 行うことができるという効果が得られる。 Further, according to the gamma correction device according to claim 3 of the present invention, in the gamma correction device according to claim 1, the gamma correction device according to claim 1, When the correction value storage means stores the gamma correction value for the discrete input value obtained by reading the predetermined image, the gamma correction value for the low gradation part is stored more, so that the amount of change is large. By storing more gamma correction values in the low gradation area, gamma correction can be performed for each element with less storage capacity and high accuracy. The effect that can be performed is obtained.
また、 本発明の請求の範囲第 4項に係るガンマ補正装置によれば、 複数の撮像 素子のガンマ特性を補正するガンマ補正装置において、 基準素子のガンマ補正値 と、 それぞれ位置的に隣接する素子どうしのガンマ補正値の差分値とを、 予め定 めた記憶容量で記憶するガンマ補正値記憶手段と、 基準素子は記憶してあるガン マ補正値を用い、 それ以外の素子では、 基準素子のガンマ補正値に当該素子の位 置までに存在する素子の差分値をそれぞれ積算することで、 素子毎の gなんま補 正値を算出するガンマ補正値算出手段と、 上記算出したガンマ補正値から素子毎 にガンマ補正を行うガンマ補正手段とを備えたものとしたので、 位置的に隣り合 う素子のガンマ補正値の差分値を予め定めた記憶容量で記憶させることで、 効率 良く、 少ない記憶容量で素子毎にガンマ補正を行うことができるという効果が得 られる。  Further, according to the gamma correction device according to claim 4 of the present invention, in a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, a gamma correction value of a reference device and a device that is positionally adjacent to each other A gamma correction value storage means for storing a difference value between two gamma correction values with a predetermined storage capacity, and a gamma correction value stored as a reference element. Gamma correction value calculating means for calculating a gamma correction value for each element by integrating the difference value of the element existing up to the position of the element with the gamma correction value, and a gamma correction value calculated from the calculated gamma correction value. Since gamma correction means for performing gamma correction is provided for each element, the difference between the gamma correction values of elements adjacent in position is stored in a predetermined storage capacity, so that efficiency is improved. There is an advantage that it is possible to perform the gamma correction for each element in the absence storage capacity.
また、 本発明の請求の範囲第 5項に係るガンマ補正装置によれば、 上記請求の 範囲第 4項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記 ガンマ補正値記憶手段に記憶してある所定の画像の入力値どガンマ捕正値とから 補間処理を行い、 素子毎のガンマ補正値を算出するガンマ補正値補間手段を備え たものとしたので、 位置的に隣り合う素子のガンマ補正値の差分値を予め定めた 記憶容量で記憶させ、 さらに離散的な入力値に対するガンマ捕正値のみを記憶さ せることでより少ない記憶容量で素子毎にガンマ補正を行うことができるという 効果が得られる。  Further, according to the gamma correction device according to claim 5 of the present invention, in the gamma correction device according to claim 4, the gamma correction value storage means stores the discrete image obtained by reading a predetermined image. The gamma correction values for the various input values are stored, and interpolation processing is performed from the gamma correction values and the input values of the predetermined image stored in the gamma correction value storage means to calculate the gamma correction values for each element. Gamma correction value interpolation means for storing the difference value of the gamma correction value of the element adjacent in position with a predetermined storage capacity, and furthermore, only the gamma correction value for a discrete input value is stored. By storing the information, the effect that gamma correction can be performed for each element with a smaller storage capacity can be obtained.
また、 本発明の請求の範囲第 6項に係るガンマ捕正装置によれば、 上記請求の 範囲第 4項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階 調部のガンマ捕正値をより多く記憶するようにしたので、 変化量の大きい低階調 部のガンマ補正値をより多く記憶させることで、 少ない記憶容量で精度よく素子 毎にガンマ補正を行うことができるという効果が得られる。  Further, according to the gamma correction device according to claim 6 of the present invention, in the gamma correction device according to claim 4, wherein the gamma correction value storage means reads a predetermined image from a discrete image. When storing the gamma correction value for a typical input value, more gamma correction values are stored in the low gradation part because the gamma correction value in the low gradation part is stored more. As a result, an effect is obtained that gamma correction can be accurately performed for each element with a small storage capacity.
また、 本発明の請求の範囲第 7項に係るガンマ補正装置によれば、 複数の撮像 素子のガンマ特性を補正するガンマ補正装置において、 基準素子のガンマ補正値 と、 それぞれ位置的に隣接する素子どうしのガンマ補正値の差分値とを、 予め定 めた記憶容量で記憶し、 差分値が予め定めた記憶容量を超過した場合、 隣接する 素子では差分値に超過した値を加算して記憶するガンマ捕正値記憶手段と、 基準 素子は記憶してあるガンマ補正値を用い、 それ以外の素子では、 基準素子のガン マ補正値に当該素子の位置までに存在する素子の差分値をそれぞれ積算すること で、 素子毎のガンマ補正値を算出するガンマ補正値算出手段と、 上記算出したガ ンマ捕正値から素子毎にガンマ補正を行うガンマ補正手段とを備えたものとした ので、 位置的に隣り合う素子のガンマ補正値の差分値を記憶させることで、 少な レ、記憶容量で素子毎にガンマ補正を行うことができると共に、 差分値が差分値を 記憶する容量を超過した場合でもその誤差を最小限に抑えることができるという 効果が得られる。 Further, according to the gamma correction device according to claim 7 of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of imaging devices, the gamma correction value of the reference device And the difference value of the gamma correction value between the elements adjacent to each other with a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, the difference value is calculated for the adjacent element. The gamma correction value storage means for adding and storing the excess value, and the reference element uses the stored gamma correction value, and for the other elements, the gamma correction value of the reference element is added to the position of the element. Gamma correction value calculation means for calculating a gamma correction value for each element by integrating the difference values of the existing elements, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. By storing the difference value of the gamma correction value of the element adjacent in position, gamma correction can be performed for each element with a small amount of storage capacity, and the difference value Record Effect that the error even in excess of capacity can be suppressed to a minimum is obtained.
また、 本発明の請求の範囲第 8項に係るガンマ補正装置によれば、 上記請求の 範囲第 7項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記 ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値とから 補間処理を行い、 素子毎のガンマ捕正値を算出するガンマ補正値補間手段を備え たものとしたので、 差分値が差分値を記憶する容量を超過した場合でも、 その誤 差を最小限に抑えることができ、 また、 離散的な入力値に対するガンマ補正値を 記憶することでガンマ補正値の記憶容量を小さくすことができるという効果が得 られる。  Further, according to the gamma correction device according to claim 8 of the present invention, in the gamma correction device according to claim 7, the gamma correction value storage means stores a discrete image obtained by reading a predetermined image. The gamma correction values for the various input values are stored, and interpolation processing is performed from the input values of the predetermined image and the gamma correction values stored in the gamma correction value storage means to calculate a gamma correction value for each element. Since the gamma correction value interpolation means is provided, even if the difference value exceeds the capacity for storing the difference value, the error can be minimized. Storing the correction value has the effect of reducing the storage capacity of the gamma correction value.
また、 本発明の請求の範囲第 9項に係るガンマ補正装置によれば、 上記請求の 範囲第 7項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定 の画像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階 調部のガンマ捕正値をより多く記憶するようにしたので、 差分値が差分値を記憶 する容量を超過した場合でも、 その誤差を最小限に抑えることができ、 また、 変 化量の大きレ、低階調部のガンマ補正値をより多く記憶させることで少なレ、記憶容 量で精度よく素子毎にガンマ補正を行うことができるという効果が得られる。 また、 本発明の請求の範囲第 1 0項に係るガンマ補正装置によれば、 複数の撮 像素子のガンマ特性を補正するガンマ補正装置において、 入力値毎の各素子のガ ンマ補正値の平均値と、 該平均値と上記各素子毎のガンマ補正値との差分値を記 憶したガンマ補正値記憶手段と、 素子毎のガンマ捕正値を、 上記ガンマ補正値の 平均値に、 素子毎の差分値を加算して算出するガンマ捕正値算出手段と、 上記算 出したガンマ補正値から素子毎にガンマ補正を行うガンマ補正手段とを備えたも のとしたので、 素子毎に独立して平均値に差分値を加算してガンマ補正値を算出 するため正確にガンマ補正を行うことができるという効果が得られる。 Further, according to the gamma correction device according to claim 9 of the present invention, in the gamma correction device according to claim 7, wherein the gamma correction value storage means reads a predetermined image and stores the discrete image. When storing gamma correction values for various input values, more gamma correction values in the low-tone part are stored, so even if the difference value exceeds the capacity to store the difference value, the error is reduced. The gamma correction can be minimized, and the amount of change is large, and the gamma correction value of the low gradation part is stored more, so that the gamma correction can be accurately performed for each element with a small amount. The effect that it can be obtained is obtained. Further, according to the gamma correction apparatus according to claim 10 of the present invention, in a gamma correction apparatus for correcting gamma characteristics of a plurality of imaging elements, the gamma correction of each element for each input value is provided. Gamma correction value storage means for storing an average value of the gamma correction values, a difference value between the average value and the gamma correction value for each element, and a gamma correction value for each element. Gamma correction value calculating means for calculating a difference value for each element to calculate the gamma correction value, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. Since the gamma correction value is calculated by adding the difference value to the average value independently for each element, it is possible to perform the gamma correction accurately.
また、 本発明の請求の範囲第 1 1項に係るガンマ補正装置によれば、 上記請求 の範囲第 1◦項記載のガンマ捕正装置において、 上記ガンマ捕正値記憶手段は、 所定の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ捕正値と から補間処理を行い、 素子毎のガンマ補正値を算出するガンマ補正値補間手段を 備えたものとしたので、 素子毎に独立して平均値に差分値を加算してガンマ補正 値を算出して正確なガンマ補正を行うことができ、 また、 離散的な入力値に対す るガンマ補正値を記憶させることで、 ガンマ捕正値の記憶容量を小さくすること ができるという効果が得られる。  According to the gamma correction device according to claim 11 of the present invention, in the gamma correction device according to claim 1 ◦, the gamma correction value storage means stores a predetermined image. A gamma correction value corresponding to the read discrete input value is stored. Interpolation processing is performed from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means, and the gamma correction for each element is performed. The gamma correction value interpolation means for calculating the correction value is provided, so that the gamma correction value can be calculated by adding the difference value to the average value independently for each element to calculate the gamma correction value. Also, by storing the gamma correction value for the discrete input value, the effect of reducing the storage capacity of the gamma correction value can be obtained.
また、 本発明の請求の範囲第 1 2項に係るガンマ捕正装置によれば、 上記請求 の範囲第 1 0項記載のガンマ補正装置において、 上記ガンマ捕正値記憶手段は、 所定の画像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階調部のガンマ捕正値をより多く記憶するようにしたので、 素子毎に独立して 平均値に差分値を加算してガンマ補正値を算出して、 正確にガンマ補正を行え、 また、 離散的な入力値に対するガンマ補正値のなかで、 変化量の大きい低階調部 をより多く記憶させることで精度よく記憶容量を小さくすることができるという 効果が得られる。  Further, according to the gamma correction device according to claim 12 of the present invention, in the gamma correction device according to claim 10, the gamma correction value storage means stores a predetermined image. When storing the gamma correction values for the read discrete input values, more gamma correction values for the low gradation area are stored, so the difference value is added to the average value independently for each element. The gamma correction value can be calculated to accurately perform gamma correction.Moreover, among the gamma correction values for discrete input values, more low-gradation parts with a large change amount are stored more accurately to achieve storage capacity. Therefore, the effect of being able to reduce is obtained.
また、 本発明の請求の範囲第 1 3項に係るガンマ補正装置によれば、 複数の撮 像素子のガンマ特性を補正するガンマ補正装置において、 基準素子のガンマ捕正 値と、 それぞれ位置的に隣接する素子どうしのガンマ補正値との差分値と、 該差 分値のデータ長を記憶するガンマ補正値記憶手段と、 基準素子は記憶してあるガ ンマ補正値によりガンマ補正を行い、 それ以外の素子では基準素子のガンマ補正 値に当該素子の位置までに存在する素子の差分値をそれぞれ積算することで、 素 子毎のガンマ補正値を算出するガンマ補正値算出手段と、 上記算出したガンマ捕 正値から素子毎にガンマ補正を行うガンマ補正手段とを備えたものとしたので、 位置的に隣り合う素子のガンマ補正値の差分値を、 差分値の大きさに合わせて効 率良く記億させることで、 少ない記憶容量で素子毎にガンマ補正を行うことがで きるという効果が得られる。 Further, according to the gamma correction apparatus according to claim 13 of the present invention, in a gamma correction apparatus for correcting gamma characteristics of a plurality of imaging elements, a gamma correction value of a reference element and a gamma correction value of a reference element are each set. Gamma correction value storage means for storing the difference value between the gamma correction values of adjacent elements, the data length of the difference value, and the reference element perform gamma correction based on the stored gamma correction values. For the element of, the difference value of the element existing up to the position of the element is added to the gamma correction value of the reference element, thereby obtaining the element Gamma correction value calculating means for calculating a gamma correction value for each element, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value are provided. By efficiently storing the difference value of the gamma correction value according to the magnitude of the difference value, the effect that gamma correction can be performed for each element with a small storage capacity can be obtained.
また、 本発明の請求の範囲第 1 4項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 3項記載のガンマ捕正装置において、 上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対するガンマ補正値を記憶しており、 上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値と から補間処理を行い、 素子毎のガンマ補正値を算出するガンマ補正値補間手段を 備えたものとしたので、 位置的に隣り合う素子のガンマ補正値の差分値を、 差分 値の大きさに合わせて効率良く記憶させ、 さらに、 離散的な入力値に対するガン マ補正値のみを記憶させることで、 より少ない記憶容量で素子毎にガンマ補正を '行うことができるという効果が得られる。  Further, according to the gamma correction device according to claim 14 of the present invention, in the gamma correction device according to claim 13, the gamma correction value storage means reads a predetermined image. A gamma correction value for a discrete input value is stored. The gamma correction value is interpolated from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means, and the gamma correction value for each element is obtained. The gamma correction value interpolating means for calculating the gamma correction value is calculated, so that the difference value of the gamma correction value of the element adjacent in position is efficiently stored according to the magnitude of the difference value. By storing only the gamma correction value for the value, the effect is obtained that gamma correction can be performed for each element with a smaller storage capacity.
また、 本発明の請求の範囲第 1 5項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 3項記載のガンマ補正装置において、 上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対するガンマ補正値を記憶する際に、 低階調部のガンマ補正値をより多く記憶するようにしたので、 変化量の大きい低 階調部のガンマ補正値をより多く記憶させることで少ない記憶容量で精度よく素 子毎にガンマ補正を行うことができるという効果が得られる。  According to a gamma correction device according to claim 15 of the present invention, in the gamma correction device according to claim 13, the gamma correction value storage means reads a predetermined image. When storing gamma correction values for discrete input values, more gamma correction values are stored in the low gradation area, so that more gamma correction values are stored in the low gradation area with large changes. As a result, the effect that gamma correction can be accurately performed for each element with a small storage capacity can be obtained.
また、 本発明の請求の範囲第 1 6項に係るガンマ補正装置によれば、 複数の撮 像素子のガンマ特性を補正するガンマ補正装置において、 複数のガンマ補正テー ブルを記憶するガンマ補正テーブル記憶手段と、 素子毎にガンマ補正テーブルを 選択するための選択情報を記憶するガンマ補正テーブル選択情報記憶手段と、 上 記ガンマ補正テーブル記憶手段と上記ガンマ補正テーブル選択情報記憶手段とか ら素子毎に対応したガンマ捕正テ一ブルを選択するガンマ補正テーブル選択手段 と、 選択したガンマ補正テーブルによりガンマ補正を行うガンマ補正手段とを備 えたものとしたので、 素子毎に該当するガンマ補正テーブルの選択情報のみを記 憶させることにより、記憶容量を小さくすることができるという効果が得られる。 また、 本発明の請求の範囲第 1 7項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 6項記載のガンマ補正装置において、 上記ガンマ補正テーブル記憶手 段は、 ガンマ補正量が最も小さいガンマ補正テーブル、 あるいはガンマ補正量が 最も大きいガンマ補正テーブルを基準のガンマ補正テーブルとして記憶し、 その 他のガンマ補正テーブルは、 基準のガンマ補正テーブルがガンマ補正量の最も小 さいガンマ補正テーブルを用いる場合は、 ガンマ補正量が小さい順番にガンマ補 正テーブルを並べた場合に順番が隣り合うガンマ補正値の差分値を記憶し、一方、 基準のガンマ捕正テーブルとしてガンマ補正量の最も大きいガンマ補正テープノレ を用いる場合は、 ガンマ補正量が大きレ、1頃番にガンマ補正テーブルを並べた場合 に順番が隣り合うガンマ補正値の差分値を記憶し、 上記基準のガンマ捕正テープ ルと差分値とからガンマ捕正テープノレを算出するガンマ捕正テープノレ算出手段を 備えたものとしたので、 複数のガンマ補正テープルをガンマ捕正テーブル記憶手 段に記憶させる際に、 ガンマ補正特性の近いガンマ捕正テーブルどうしの差分値 を記憶することにより、 ガンマ捕正テーブル記憶手段の記憶容量を小さくするこ とができるという効果が得られる。 Further, according to the gamma correction device according to claim 16 of the present invention, in a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, a gamma correction table storage for storing a plurality of gamma correction tables Means, gamma correction table selection information storage means for storing selection information for selecting a gamma correction table for each element, and gamma correction table storage means and gamma correction table selection information storage means for each element. Gamma correction table selection means for selecting the selected gamma correction table, and gamma correction means for performing gamma correction based on the selected gamma correction table, so that the gamma correction table selection information corresponding to each element is provided. By storing only the data, the effect of reducing the storage capacity can be obtained. Further, according to the gamma correction device according to claim 17 of the present invention, in the gamma correction device according to claim 16, the gamma correction table storage means has the most gamma correction amount. A small gamma correction table or a gamma correction table with the largest amount of gamma correction is stored as a reference gamma correction table, and the other gamma correction tables are based on the gamma correction table with the smallest gamma correction amount. When the gamma correction table is used, when the gamma correction tables are arranged in ascending order, the difference value of the gamma correction values that are adjacent to each other is stored. When using the correction tape, the gamma correction amount is large, and the gamma correction table Has a gamma correction tape loss calculating means for storing a difference value between adjacent gamma correction values and calculating a gamma correction tape loss from the reference gamma correction table and the difference value. When the correction table is stored in the gamma correction table storage means, the storage capacity of the gamma correction table storage means can be reduced by storing the difference value between the gamma correction tables having similar gamma correction characteristics. The effect that can be obtained is obtained.
また、 本発明の請求の範囲第 1 8項に係るガンマ捕正装置によれば、 上記請求 の範囲第 1 6項記載のガンマ補正装置において、 上記ガンマ補正テーブル選択手 段は、 素子のガンマ補正テーブルと、 ガンマ補正テーブル記憶手段に記憶してあ る複数のガンマ補正テーブルとで、 ガンマ補正値の最小二乗和が最も小さくなる ガンマ補正テーブルを選択するようにしたので、 予め複数のガンマ補正テーブル を記憶させておき、 素子毎にそのガンマ補正テーブルの選択情報のみを記憶させ ることにより、 記憶容量を小さくすることができると共に、 正確に最適なガンマ 補正テーブルを選択することができるという効果が得られる。  Further, according to the gamma correction device according to claim 18 of the present invention, in the gamma correction device according to claim 16, the gamma correction table selecting means includes: The gamma correction table that minimizes the least square sum of the gamma correction values is selected from the table and the plurality of gamma correction tables stored in the gamma correction table storage means. By storing only the selection information of the gamma correction table for each element, the storage capacity can be reduced and the optimal gamma correction table can be selected accurately. can get.
また、 本発明の請求の範囲第 1 9項に係るガンマ補正装置によれば、 複数の撮 像素子のガンマ特性を捕正するガンマ捕正装置において、 ガンマ補正前の基準素 子の入力値に対する出力特性捕正値である素子特性補正値と、 それぞれ位置的に 隣接する素子どうしにおける、 ガンマ補正前の入力値に対する出力特性補正値で ある素子特性捕正値の差分値とを、 予め定めた記憶容量で記憶する素子特' 14補正 値記憶手段と、 基準素子は記憶してある素子特性補正値によりガンマ捕正値を算 出し、 それ以外の素子では、 基準素子の素子特性補正値に当該素子の位置までに 存在する素子の差分値をそれぞれ積算することで、 素子毎のガンマ補正値を算出 する素子特性補正値算出手段と、 上記算出した素子毎の特性補正値から素子毎に ガンマ補正値を算出するガンマ捕正値算出手段と、 上記算出したガンマ補正値か ら素子毎にガンマ補正を行うガンマ捕正手段とを備えたものとしたので、 素子間 の特性の差が小さいガンマ捕正前の特性補正値の差分値を記億させることで、 よ り少ない記憶容量で素子毎にガンマ捕正を行うことができる'という効果が得られ る。 Further, according to the gamma correction device according to claim 19 of the present invention, in a gamma correction device for correcting gamma characteristics of a plurality of imaging elements, a gamma correction device for input values of a reference element before gamma correction is provided. The element characteristic correction value, which is the output characteristic correction value, and the difference value between the element characteristic correction value, which is the output characteristic correction value for the input value before gamma correction, between the elements adjacent to each other, are predetermined. The element characteristics to be stored by the storage capacity (14) The correction value storage means and the reference element calculate the gamma correction value based on the stored element characteristic correction value. For other elements, the element characteristic correction value calculating means for calculating the gamma correction value for each element by integrating the element characteristic correction value of the reference element with the difference value of the element existing up to the position of the element. Gamma correction value calculating means for calculating a gamma correction value for each element from the calculated characteristic correction value for each element, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. The gamma correction can be performed for each element with a smaller storage capacity by storing the difference between the characteristic correction values before gamma correction, where the difference in characteristics between the elements is small. 'Is obtained.
また、 本発明の請求の範囲第 2 0項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 9項記載のガンマ補正装置において、 上記素子特性記憶手段は、 位置 的に隣接する素子どうしの素子特性補正値の差分値を予め定めた記憶容量で記憶 し、 差分値が予め定めた記憶容量を超過した場合、 隣接する素子では差分値に超 過した値を加算して記憶するようにしたので、 素子間の特性の差が小さいガンマ 補正前の特性補正値の差分値を予め定めた記憶容量で記憶させることで、 より効 率良く少ない記憶容量で素子毎にガンマ補正を行うことができるという効果が得 られる。  Further, according to the gamma correction device according to claim 20 of the present invention, in the gamma correction device according to claim 19, the element characteristic storage means includes a pair of elements adjacent in position. When the difference value exceeds the predetermined storage capacity, the difference value of the element characteristic correction value of each element is stored in a predetermined storage capacity. Therefore, by storing the difference value of the characteristic correction value before gamma correction with a small difference in characteristics between elements with a predetermined storage capacity, it is possible to perform gamma correction for each element with a smaller storage capacity more efficiently. The effect is that it can be done.
また、 本発明の請求の範囲第 2 1項に係るガンマ捕正装置によれば、 上記請求 の範囲第 1 9項記載のガンマ補正装置において、上記素子特性捕正値記憶手段は、 素子の素子特性補正値の平均値と、 その平均値と各素子毎の素子特性補正値の差 分値とを記憶し、 上記素子特性補正値算出手段は、 各素子毎の素子特性捕正値の 平均値に、 素子毎の差分値を加算した値から素子特性補正値を算出するようにし たので、 素子間の特性の差が小さいガンマ補正前の特性補正値の差分値を記憶さ せることで、 記憶容量を小さくすることができ、 また、 差分値が差分値を記憶す る容量を超過した場合でもその誤差を最小限に抑えることができるという効果が 得られる。  Further, according to the gamma correction device according to claim 21 of the present invention, in the gamma correction device according to claim 19, the element characteristic correction value storage means includes: The average value of the characteristic correction values and the difference between the average value and the element characteristic correction value of each element are stored, and the element characteristic correction value calculating means calculates the average value of the element characteristic correction values of each element. In addition, the element characteristic correction value is calculated from the value obtained by adding the difference value of each element, so that the difference value of the characteristic correction value before gamma correction, in which the characteristic difference between elements is small, is stored. The effect is obtained that the capacity can be reduced, and even if the difference value exceeds the capacity for storing the difference value, the error can be minimized.
また、 本発明の請求の範囲第 2 2項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 9項記載のガンマ補正装置において、 上記素子特性記憶手段は、 位置 的に隣接する素子どうしの素子特性捕正値の差分値をそのデータ長と共に記憶す るようにしたので、 素子間の特性の差が小さいガンマ補正前の特性捕正値の差分 値を記憶させることにより、 記憶容量を小さくすることができ、 また、 素子毎に- 独立して平均値に差分値を加算することにより特性補正値を算出し、 その特性補 正値からガンマ捕正値を算出するため、 正確にガンマ補正を行うことができると いう効果が得られる。 Further, according to the gamma correction device according to claim 22 of the present invention, in the gamma correction device according to claim 19, the element characteristic storage means includes a pair of elements adjacent in position. Since the difference between the element characteristic correction values of the elements is stored together with the data length, the difference between the characteristic correction values before gamma correction where the characteristic difference between the elements is small By storing the values, the storage capacity can be reduced.In addition, for each element, a characteristic correction value is calculated by independently adding the difference value to the average value, and the gamma capture is calculated from the characteristic correction value. Since the positive value is calculated, the effect that the gamma correction can be performed accurately can be obtained.
また、 本発明の請求の範囲第 2 3項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 9項記載のガンマ補正装置において、上記素子特性補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対する素子特性補正値を記憶し、 上記 素子特性補正値補間手段は、，上記素子特性補正値記憶手段に記憶してある所定の 画像の入力値と素子特性捕正値とから補間処理を行つて素子毎の素子特性補正値 を算出するようにしたので、 素子間の特性の差が小さいガンマ補正前の特性補正 値の差分値を記憶させると共に、 離散的な入力値に対する特性補正値を記憶する ことにより、 さらに記憶容量を減らすことができるという効果が得られる。  According to a gamma correction device according to claim 23 of the present invention, in the gamma correction device according to claim 19, the element characteristic correction value storage means reads a predetermined image. The element characteristic correction value interpolating means stores the element value and the element characteristic correction value for the predetermined image stored in the element characteristic correction value storage means. Calculates the element characteristic correction value for each element by performing interpolation processing from, so that the difference value of the characteristic correction value before gamma correction where the characteristic difference between the elements is small is stored, and the discrete input value Storing the characteristic correction value has the effect of further reducing the storage capacity.
また、 本発明の請求の範囲第 2 4項に係るガンマ補正装置によれば、 上記請求 の範囲第 1 9項記載のガンマ補正装置において、上記素子特性補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対する素子特性補 IE値を記憶させる際 に、 低階調部の素子特性補正値をより多く記憶させるようにしたので、 素子間の 特性の差が小さいガンマ補正前の特性補正値の差分値を記憶させることで記憶容 量を減らすと共に、 ガンマ補正後に変化量が大きくなる低階調部の特性捕正値を より多く記憶させることで、 少ない記憶容量で精度よく素子毎にガンマ捕正を行 うことができるという効果がある。 図面の簡単な説明'  According to the gamma correction apparatus of claim 24 of the present invention, in the gamma correction apparatus of claim 19, the element characteristic correction value storage means reads a predetermined image. When storing the element characteristic compensation IE values for discrete input values, more element characteristic correction values in the low gradation area are stored, so that the characteristics before gamma correction have small differences in the characteristics between the elements. By storing the difference value of the correction value, the storage capacity is reduced, and by storing more characteristic correction values of the low gradation part where the amount of change becomes large after gamma correction, each element can be accurately stored with a small storage capacity. This has the effect that gamma correction can be performed. Brief Description of the Drawings'
第 1図は、 本発明の実施の形態 1 におけるガンマ補正装置の構成を示すプロ ック図である。  FIG. 1 is a block diagram showing a configuration of a gamma correction device according to Embodiment 1 of the present invention.
第 2図は、 上記実施の形態 1によるガンマ補正装置が適用されるイメージスキ ャナの構成を示す図である。  FIG. 2 is a diagram showing a configuration of an image scanner to which the gamma correction device according to the first embodiment is applied.
第 3図は、 上記実施の形態 1におけるガンマ捕正装置のガンマ捕正値の一例を 示した図である。  FIG. 3 is a diagram illustrating an example of a gamma correction value of the gamma correction device according to the first embodiment.
第 4図は、 本発明の実施の形態 2におけるガンマ補正装置の構成を示すプロッ ク図である。 FIG. 4 is a plot showing the configuration of a gamma correction device according to Embodiment 2 of the present invention. FIG.
第 5図は、 ガンマ補正値を算出するのに用いられるグレーチヤ一トの一例を示 す図である。  FIG. 5 is a diagram showing an example of a grid used for calculating a gamma correction value.
第 6図は、 1 0パターンのグレーチャートに対するガンマ捕正値の一例を示す 図である。  FIG. 6 is a diagram showing an example of a gamma correction value for a 10-pattern gray chart.
第 7図は、 データ間を直線補間する補間処理を説明するための図である。  FIG. 7 is a diagram for explaining an interpolation process for performing linear interpolation between data.
第 8図は、 ガンマ補正曲線がガンマ 2 . 2の値をもつ理想ガンマ曲線を 1 0個 の離散的なデータで直線近似する場合の一例を示す図である。  FIG. 8 is a diagram showing an example of a case where an ideal gamma curve whose gamma correction curve has a value of gamma 2.2 is linearly approximated by 10 discrete data.
第 9図は、 低階調領域のデータ数をより多くとって理想ガンマ曲線との誤差を 最小限にする補間処理の一例を示す図である。  FIG. 9 is a diagram illustrating an example of an interpolation process for minimizing an error from an ideal gamma curve by increasing the number of data in the low gradation area.
第 1 0図は、 本発明の実施の形態 3におけるガンマ補正装置の構成を示すプロ ック図である。  FIG. 10 is a block diagram showing a configuration of a gamma correction device according to Embodiment 3 of the present invention.
第 1 1図は、 上記実施の形態 3におけるガンマ補正装置 構成するガンマ補正 値記憶手段に記憶する差分値を算出する方法を説明するためめ図である。 ' 第 1 2図は、 本発明の実施の形態 4におけるガンマ捕正装置の構成を示すプロ ック図である。  FIG. 11 is a diagram for explaining a method of calculating a difference value stored in a gamma correction value storage unit included in the gamma correction device according to the third embodiment. FIG. 12 is a block diagram showing a configuration of a gamma correction device according to Embodiment 4 of the present invention.
第 1 3図は、 上記実施の形態 4におけるガンマ補正装置の差分値からガンマ捕 正値を復元するための方法を説明するための図である。  FIG. 13 is a diagram for explaining a method for restoring a gamma correction value from a difference value of the gamma correction device according to the fourth embodiment.
第 1 4図は、 本発明の実施の形態 5におけるガンマ捕正装置による補間方法用 いる前の問題点を説明するための図である。  FIG. 14 is a diagram for explaining a problem before using the interpolation method by the gamma correction device according to the fifth embodiment of the present invention.
第 1 5図は、 本発明の実施の形態 5におけるガンマ補正装置を用いた補間処理 を説明するための図である。  FIG. 15 is a diagram for explaining an interpolation process using the gamma correction device according to the fifth embodiment of the present invention.
第 1 6図は、  Figure 16 shows
本発明の実施の形態 6におけるガンマ補正装置の構成を示すプロック図である。 第 1 7図は、 上記実施の形態 6におけるガンマ捕正装置による差分値算出方法 を説明するための図である。  FIG. 16 is a block diagram illustrating a configuration of a gamma correction device according to a sixth embodiment of the present invention. FIG. 17 is a diagram for explaining a difference value calculation method by the gamma correction device according to the sixth embodiment.
第 1 8図は、 本発明の実施の形態 7におけるガンマ補正装置の構成を示すプロ ック図である。  FIG. 18 is a block diagram showing a configuration of a gamma correction device according to Embodiment 7 of the present invention.
第 1 9図は、 上記実施の形態 7におけるガンマ捕正装置のガンマ補正値記憶回 路への記録方法を説明するための図である。 FIG. 19 is a diagram showing a gamma correction value storage circuit of the gamma correction device according to the seventh embodiment. It is a figure for explaining the recording method to a road.
第 2 0図は、 上記実施の形態 7によるガンマ補正装置のガンマ補正値記憶回路 へ、 差分値のデータ長を一緒に記憶させた状態を説明するためのイメージ図であ る。  FIG. 20 is an image diagram for explaining a state in which the data length of the difference value is stored together in the gamma correction value storage circuit of the gamma correction device according to the seventh embodiment.
第 2 1図は、 上記実施の形態 7によるガンマ補正値のデータ長とガンマ捕正値 とを順次記憶していく場合のイメージ図である。  FIG. 21 is an image diagram in the case of sequentially storing the data length of the gamma correction value and the gamma correction value according to the seventh embodiment.
第 2 2図は、 本発明の実施の形態 8によるガンマ補正装置の構成を示すブロッ ク図である。  FIG. 22 is a block diagram showing a configuration of a gamma correction device according to Embodiment 8 of the present invention.
第 2 3図は、 上記実施の形態 8におけるガンマ補正装置の変形例の構成を示す プロック図である。 - 第 2 4図は、 本発明の実施の形態 9におけるガンマ捕正装置の構成を示すプロ ック図である。  FIG. 23 is a block diagram showing a configuration of a modification of the gamma correction device according to the eighth embodiment. FIG. 24 is a block diagram showing a configuration of a gamma correction device according to Embodiment 9 of the present invention.
第 2 5図は、 上記実施の形態 9におけるガンマ補正装置において、 素子特性と 理想特性との関係を示す図である。  FIG. 25 is a diagram showing a relationship between element characteristics and ideal characteristics in the gamma correction device according to the ninth embodiment.
第 2 6図は、 上記実施の形態 Ίにおけるガンマ補正装置の差分値算出方法を説 明するための図である。  FIG. 26 is a diagram for explaining a difference value calculation method of the gamma correction device in the above embodiment 2.
第 2 7図は、 ガンマ補正テープルを格納した R OMを用いたガンマ補正の方法 を概念的に説明するための図である。  FIG. 27 is a diagram conceptually illustrating a gamma correction method using a ROM storing a gamma correction table.
第 2 8図は、 従来のガンマ補正装置の構成を示すブロック図である。  FIG. 28 is a block diagram showing a configuration of a conventional gamma correction device.
第 2 9図は、 従来のガンマ捕正装置によるガンマ補正の方法を説明するための 図である。  FIG. 29 is a diagram for explaining a gamma correction method using a conventional gamma correction device.
第 3 0図は、 従来のガンマ補正装置における差分値算出方法を説明するための 図である。 発明を実施するための最良の形態  FIG. 30 is a diagram for explaining a difference value calculation method in a conventional gamma correction device. BEST MODE FOR CARRYING OUT THE INVENTION
(実施の形態 1 . )  (Embodiment 1)
以下に、 本発明の実施の形態 1にかかるガンマ補正装置について、 図を参照し ながら説明する。 第 1図は本実施の形態 1のガンマ補正装置の構成を示すプロッ ク図である。 第 1図において、 1 0 1は C C D等の撮像素子、 1 0 2は C C D 1 0 1の出力をデジタルに変換する A/Dコンバータ、 1 0 3は AZDコンバータ 1 0 2の出力を受けるガンマ補正回路、 1 0 4はガンマ補正値記憶回路 1 0 5か ら必要なガンマ補正値を選択して取り出すガンマ補正テーブル選択回路、 1 0 6 は素子選択回路である。 Hereinafter, the gamma correction device according to the first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the gamma correction device according to the first embodiment. In FIG. 1, 101 is an image sensor such as a CCD, and 102 is a CCD 1 0 A / D converter that converts the output of 1 to digital, 103 is the gamma correction circuit that receives the output of the AZD converter 102, 104 is the required gamma correction value from the gamma correction value storage circuit 105 Is a gamma correction table selection circuit, and 106 is an element selection circuit.
以下、 作について説明する。  Hereinafter, the work will be described.
撮像素子 1 0 1で入力画像を取り込み、 AZDコンバータ 1 0 2で入力信号を デジタル化した後、 各素子毎に個別のガンマ捕正値を用いてガンマ補正回路 1 0 3にてガンマ補正を行う。 ここで、 素子毎のガンマ捕正値は、 ガンマ補正値記憶 回路 1 0 5に記憶してあるガンマ補正テーブルから、 該当する素子のガンマ補正 テープ <レをガンマ捕正テーブル選択回路 1 0 4にて選択し、 選択したガンマ補正 テーブルのガンマ補正値をもとにガンマ補正回路 1 0 3にてガンマ補正を行う。 イメージスキャナは、 第 2図に示すような構成により画像！:読み取つている。 すなわち、 第 2図において、 2 0 1は読み取り原稿、 2 0 2は照明、 2 0 3は読 み取り原稿 2 0 1と撮像素子 2 0 4との間に配置されたレンズである。  After the input image is captured by the image sensor 101 and the input signal is digitized by the AZD converter 102, the gamma correction is performed by the gamma correction circuit 103 using the individual gamma correction value for each device. . Here, the gamma correction value for each element is stored in the gamma correction table stored in the gamma correction value storage circuit 105, and the gamma correction tape of the corresponding element is stored in the gamma correction table selection circuit 104. The gamma correction circuit 103 performs gamma correction based on the gamma correction value in the selected gamma correction table. The image scanner uses an image as shown in Fig. 2! : Reading. That is, in FIG. 2, reference numeral 201 denotes a read original, reference numeral 202 denotes illumination, and reference numeral 203 denotes a lens disposed between the read original 201 and the image sensor 204.
読み取り原理は、 上記読み取り原稿 2 0 1を照明 2 0 2にて照らして、 その反 射光をレンズ 2 0 3にて結像し、 光の信号を撮像素子 2 0 4 こて電気信号に変換 するものである。 上記撮像素子 2 0 4は、 1番素子から N番素子までの複数の素 子で構成され、 素子毎に光の信号を電気信号に変換してレ、る。  The reading principle is as follows. The reading document 201 is illuminated by the illumination 202, the reflected light is imaged by the lens 203, and the light signal is converted into an electric signal by the image sensor 204. Things. The imaging element 204 is composed of a plurality of elements from element 1 to element N, and converts a light signal into an electric signal for each element.
本実施の形態のガンマ補正装置では、 撮像素子 2 0 4を構成する 1番素子から N番素子まで素子毎に個別のガンマ補正テーブルを持たせてガンマ捕正を行う。 その素子毎のガンマ補正テーブルを記憶するのがガンマ補正値記憶回路 1 0 5で ある。  In the gamma correction device according to the present embodiment, gamma correction is performed by providing an individual gamma correction table for each element from the first element to the Nth element constituting the imaging element 204. The gamma correction value storage circuit 105 stores the gamma correction table for each element.
例えば、 各素子の入力値に対するガンマ補正値が第 3 ( a ) 図に示すような特 性の場合、 ガンマ捕正値記憶回路 1 0 5には、 第 3 ( b ) 図に示した値が記憶さ れることになる。 この場合、 ガンマ補正値を 8ビット、 すなわち 1バイトであら わしている。 ガンマ補正値記憶回路 1 0 5には、 まず 1番素子の入力値 0から 2 5 5に対するガンマ補正値が 1バイトで 2 5 6個格納されており、 次に 2番素子 のガンマ捕正値が同じく 1バイ卜で 2 5 6個格納されている。 このようにして撮 像素子の N番素子までのすべてのガンマ補正値が記憶されている。 N番目の素子のガンマ補正値を算出するには、 ガンマ補正テーブル選択回路 1 0 4にて、 ガンマ補正値記憶回路 1 0 5に記憶してあるガンマ補正値から N番素 子のガンマ補正値を選択する必要があるが、 これについてはガンマ補正値記憶回 路 1 0 5上で N番素子のガンマ補正値の先頭ァドレスが、 For example, if the gamma correction value corresponding to the input value of each element has the characteristic shown in FIG. 3 (a), the gamma correction value storage circuit 105 stores the value shown in FIG. 3 (b). It will be remembered. In this case, the gamma correction value is represented by 8 bits, that is, 1 byte. The gamma correction value storage circuit 105 stores 256 gamma correction values for the input values 0 to 255 of the first element in one byte, and then the gamma correction value of the second element. Are stored in a single byte. In this way, all gamma correction values up to the Nth imaging element are stored. To calculate the gamma correction value of the Nth element, the gamma correction table selection circuit 104 calculates the gamma correction value of the Nth element from the gamma correction value stored in the gamma correction value storage circuit 105. It is necessary to select the gamma correction value of the Nth element on the gamma correction value storage circuit 105.
(先頭ァドレス） = 1 * 2 5 6 * (N- 1 ) バイト  (Head address) = 1 * 2 5 6 * (N-1) bytes
で算出できるので、 この先頭ァドレスから 2 5 6バイト分のデータが素子のガン マ補正値となる。 このガンマ捕正値をもとにガンマ補正を行うことにより、 素子 毎に個別のガンマ補正を行うことができる。 Therefore, 256 bytes of data from this top address will be the gamma correction value of the element. By performing gamma correction based on this gamma correction value, individual gamma correction can be performed for each element.
このように本実施の形態によれば、 ガンマ補正値記憶回路 1 0 5に各素子毎に ガンマ補正テーブルを準備し、 各画素毎に対応した補正テーブルをガンマ補正テ . 一ブル選択手段 1 0 4を用いて選択してガンマ補正を行うようにしたので、 高精 度なガンマ補正を行うことができ、 画質の劣化を抑えることができる。  As described above, according to the present embodiment, a gamma correction table is prepared for each element in the gamma correction value storage circuit 105, and the correction table corresponding to each pixel is stored in the gamma correction table selecting means 10. Since gamma correction is selected by using 4 to perform gamma correction, highly accurate gamma correction can be performed, and deterioration in image quality can be suppressed.
(実施の形態 2 . )  (Embodiment 2)
次に本発明の実施の形態 2におけるガンマ捕正装置について説明する。 本実施 の形態では、 上記実施の形態 1に示した構成において、 ガンマ補正テーブルを小 さくするために、 0から 2 5 5までの連続した入力データに対するガンマ捕正値 を記憶するのではなく、 何点かの離散的な入力データに対するガンマ補正値を記 憶するようにしたものである。 第 4図は本実施の形態 2によるガンマ補正装置の 回路ブロック図を示す。 第 4図において、 第 1図と同一符号ほ同一または相当部 分を示し、 ガンマ捕正値補間回路 4 0 4とパターン値記憶回路 4 0 8が付加され ている点が第 1図と異なる。  Next, a gamma correction device according to Embodiment 2 of the present invention will be described. In the present embodiment, instead of storing the gamma correction values for continuous input data from 0 to 255 in order to reduce the gamma correction table in the configuration shown in the first embodiment, The gamma correction values for some discrete input data are stored. FIG. 4 is a circuit block diagram of a gamma correction device according to the second embodiment. In FIG. 4, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and differ from FIG. 1 in that a gamma correction value interpolation circuit 404 and a pattern value storage circuit 408 are added.
一般にガンマ補正値を算出するには、 第 5図に示すような予め値のわかってい るグレーチャートをスキャナより読み込んで、 グレーチャートの値とその読み取 り値からガンマ補正値を算出し、 グレーチャートにない入力値に対するガンマ捕 正値は、 直線補間または曲線補間により値を補間してガンマ補正値を算出してい る。  Generally, to calculate the gamma correction value, a gray chart whose value is known in advance as shown in Fig. 5 is read from a scanner, the gamma correction value is calculated from the gray chart value and the read value, and the gray chart is calculated. The gamma correction value for the input value that does not exist is calculated by interpolating the value by linear interpolation or curve interpolation.
そこで、 上記ガンマ補正値記憶回路 1 0 5には、 グレーチャートのパターンに 対するガンマ補正値を記憶しておき、 捕間処理によりガンマ補正値を補間するよ うにすれば、 その記憶容量を小さくすることができる。 例えば、 第 5図に示すよ うに、 1 0パターンのグレーチャートの場合、 0から 2 5 5までの連続した入力 データに対するガンマ捕正値を記憶する場合と比較してその記憶容量を 1 0 / 2 5 6にすることができる。 以下にガンマ補正値の算出方法について述べる。 Therefore, the gamma correction value storage circuit 105 stores the gamma correction value for the gray chart pattern, and if the gamma correction value is interpolated by interpolating processing, the storage capacity can be reduced. be able to. For example, see Figure 5. Thus, in the case of a 10-pattern gray chart, the storage capacity can be reduced to 10/256 compared to storing gamma correction values for continuous input data from 0 to 255. . The method of calculating the gamma correction value will be described below.
ガンマ補正値記憶回路 1 0 5には、 パターン数分のガンマ補正値が素子毎に記 憶されており、 例えば、 1 0パターンのグレーチャートに対するガンマ補正値は 第 6図に示すようになる。 パターン値はグレーチャートの各階調毎のパターンを 測定器で測定した値である。 ガンマ補正テーブル選択回路 1 0 4では、 各素子毎 のガンマ補正テーブルを選択し、 そのガンマ補正値をガンマ補正値補間回路 4 0 4に送る。  The gamma correction value storage circuit 105 stores gamma correction values for the number of patterns for each element. For example, gamma correction values for a gray chart of 10 patterns are as shown in FIG. The pattern value is the value obtained by measuring the pattern for each gradation of the gray chart with a measuring instrument. The gamma correction table selection circuit 104 selects a gamma correction table for each element, and sends the gamma correction value to the gamma correction value interpolation circuit 404.
そしてガンマ補正値補間回路 4 0 4では、 ガンマ補正テーブル選択回路 1 0 4 で選択されたガンマ補正値と、 パターン値記憶回路 4 0 8に記憶してあるパター ン値とからガンマ補正値の補間を行う。 例えば、 第 6図の 1番素子のガンマ補正 値を補間した場合、 第 7図に示すように、 データ間を直線捕間することで補間処 理を行うことができる。 例えば、 パターン値 2 5から 5 0までの値 Xに対するガ ンマ捕正値 Yは、  The gamma correction value interpolation circuit 404 interpolates the gamma correction value from the gamma correction value selected by the gamma correction table selection circuit 104 and the pattern value stored in the pattern value storage circuit 408. I do. For example, when the gamma correction value of the first element in FIG. 6 is interpolated, as shown in FIG. 7, the interpolation processing can be performed by interpolating a straight line between the data. For example, the gamma correction value Y for the pattern value X from 25 to 50 is
A= ( 1 2 3 - 9 0 ) / ( 5 0— 2 5 )  A = (1 2 3-9 0) / (5 0— 2 5)
Y = A * (X - 2 5 ) + 9 0 Y = A * (X-25) + 90
で算出することができる。 Can be calculated.
このようにしてガンマ補正値補間回路 4 0 4にて補間されたガンマ補正値をも とに、 ガンマ補正回路 1 0 3により各素子毎にガンマ補正を行うことができる。 なお、 離散的な入力値に対するガンマ捕正値を記憶させる場合、 低階調部のパ ターン、 つまり暗い領域のパターンに対するガンマ補正値をより多く記憶させる ようにしてもよい。これはガンマ補正曲線が低階調部での変化が大きいことから、 この領域でのデータをより多くとることによりガンマ補正精度を向上させること ができるためである。  Gamma correction can be performed for each element by the gamma correction circuit 103 based on the gamma correction value interpolated by the gamma correction value interpolation circuit 404 in this manner. When storing a gamma correction value for a discrete input value, more gamma correction values may be stored for a pattern in a low gradation area, that is, a pattern in a dark area. This is because the gamma correction curve has a large change in the low gradation area, and therefore, the gamma correction accuracy can be improved by taking more data in this area.
例えば、 第 8図に示すように、 ガンマ補正曲線がガンマ 2 . 2の値をもつ理想 ガンマ曲線を 1 0個の離散的なデータで直線近似する場合、階調を均等に X ( 0 ) から X ( 9 ) で分割して近似した場合には、 低階調領域で捕藺したガンマ捕正値 と理想ガンマ曲線との誤差が大きくなることがわかる。 これはガンマ捕正曲線が 低階調部で大きく変化するためである。 そこで第 9図に示すように、 同じ 1 0個 のデータでも低階調領域のデータ数をより多くとることにより理想ガンマ曲線と の誤差を最小限にすることができることがわかる。 For example, as shown in Fig. 8, when an ideal gamma curve whose gamma correction curve has a value of gamma 2.2 is linearly approximated with 10 discrete data, the gradation is uniformly changed from X (0). It can be seen that the error between the ideal gamma curve and the gamma correction value captured in the low gradation region increases when the division is approximated by X (9). This is because the gamma correction curve This is because it changes greatly in the low gradation part. Therefore, as shown in FIG. 9, it can be seen that even with the same 10 data, the error from the ideal gamma curve can be minimized by increasing the number of data in the low gradation area.
上記第 4図に示した構造においても、 ガンマ補正値を算出する際に用いるダレ 一チャートを、 低階調部がより多いパターン、 すなわち黒に近いパターンをより 多く持つチャートにする、 またはグレーチャートの中でガンマ補正に使用するパ ターンを低階調部をより多く選択することで、 低階調部のガンマ補正値をより多 くガンマ補正値記憶回路 1 0 5に記憶させることが可能である。  In the structure shown in FIG. 4 as well, the sag chart used for calculating the gamma correction value should be a chart having more low gradation parts, that is, a chart having more patterns close to black, or a gray chart. By selecting more patterns in the low gradation area for gamma correction, the gamma correction values in the low gradation area can be stored in the gamma correction value storage circuit 105 more. is there.
このように、 本実施の形態 2によれば、 離散的な入力データに対するガンマ捕 正値をガンマ補正値記憶回路 1 0 5に記憶し、 入力データの離散度を記憶したパ ターン値記憶回路 4 0 8から該当する入力データが含まれるパターン値と、 上記 ガンマ補正値記憶回路 1 0 5に記憶されたガンマ補正値とを用いて、 ガンマ捕正 値補間回路 4 0 4にて補間処理により適切なガンマ補正値を算出してガンマ補正 を行うようにしたので、 各画素毎にガンマ捕正を行うことができ、 画質の劣化を 抑えることができるとともに、 ガンマ補正値を記憶するのに必要な記憶容量を小 さいものとすることができ、 コストダウンを図ることができる。  As described above, according to the second embodiment, the gamma correction value for the discrete input data is stored in the gamma correction value storage circuit 105, and the pattern value storage circuit 4 storing the discreteness of the input data is stored. The gamma correction value interpolation circuit 404 uses the pattern value including the corresponding input data from 08 and the gamma correction value stored in the gamma correction value storage circuit 105 to perform interpolation processing. The gamma correction is calculated by calculating a gamma correction value, so that gamma correction can be performed for each pixel, and image quality degradation can be suppressed. The storage capacity can be reduced, and costs can be reduced.
なお、 低階調領域のパターンに対するガンマ補正値をより多く記憶させること により、 補間処理による誤差を小さくすることができ、 ガンマ捕正の精度をさら に向上させることができる。  By storing more gamma correction values for the pattern in the low gradation area, the error due to the interpolation processing can be reduced, and the accuracy of gamma correction can be further improved.
また、 基準となる素子について 1番目の素子を基準素子としたが、 もちろんど の素子を基準素子としてもよい。  Although the first element is used as a reference element as a reference element, any element may be used as a reference element.
また、基準素子を 1つだけとするのではなく、何点も基準素子をもってもよい。 また、 上記離散的な入力値に対するガンマ捕正値を記憶する場合、 ダレ一チヤ ートの 1 0パターンを記憶する場合について説明したが、 パターン数もこれに限 定するものではない。  Also, instead of having only one reference element, any number of reference elements may be provided. Further, the case where the gamma correction value corresponding to the discrete input value is stored and the case where 10 patterns of the delay chart are stored have been described, but the number of patterns is not limited to this.
さらに、 ガンマ補正値を補間する場合、 直線近似で補間するのでなく、 2次曲 線等の曲線により補間するようにしてもよレ、。  Furthermore, when interpolating gamma correction values, interpolation may be performed not by linear approximation but by a curve such as a quadratic curve.
(実施の形態 3 . )  (Embodiment 3)
以下に本発明の実施の形態 3にかかるガンマ補正装置について、 図を参照しな がら説明する。 Hereinafter, the gamma correction device according to the third embodiment of the present invention will be described with reference to the drawings. I will explain.
第 1 0図は本実施の形態 3のガンマ捕正装置の構成を示すプロック図である。 第 1 0図において、 第 1図と同一符号は同一、 または相当部分を示し、 第 1図の ガンマ補正テーブル選択回路 1 0 4の代わりにガンマ捕正値算出回路 1 0 0 4力 S 設けられ、 ガンマ補正値記憶回路 1 0 5の代わりに、 基準素子のガンマ捕正テ一 ブノレと、 他の各素子のガンマ補正テーブルを上記基準素子に対する差分値として 記憶するガンマ補正値記憶回路 1 0 0 5とが設けられている点が異なっている。 以下、 動作について説明する。 撮像素子 1 0 1で入力画像を取り込み、 A/D コンバータ 1 0 2で入力信号をデジタル化した後、 各素子毎に個別のガンマ補正 値を用いてガンマ補正回路 1 0 3にてガンマ補正を行う。  FIG. 10 is a block diagram showing the configuration of the gamma correction device according to the third embodiment. In FIG. 10, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a gamma correction value calculation circuit 100 is provided instead of the gamma correction table selection circuit 104 in FIG. Instead of the gamma correction value storage circuit 105, the gamma correction value storage circuit 1005 stores the gamma correction table of the reference element and the gamma correction table of each of the other elements as a difference value with respect to the reference element. 5 is provided. Hereinafter, the operation will be described. After the input image is captured by the image sensor 101 and the input signal is digitized by the A / D converter 102, the gamma correction is performed by the gamma correction circuit 103 using individual gamma correction values for each device. Do.
ガンマ補正値は、 ガンマ補正値記憶手段 1 0 0 5に記憶してあるガンマ補正値 から、 素子選択回路 1 0 6にて選択された素子のガンマ補正値をガンマ補正値算 出回路 1 0 0 4にて算出する。  The gamma correction value is obtained by calculating the gamma correction value of the element selected by the element selection circuit 106 from the gamma correction value stored in the gamma correction value storage means 1005. Calculate in 4.
本実施の形態 3のガンマ捕正装置では、 1番素子から N番素子までの素子毎の ガンマ補正テーブルをそのまますべて記憶するのではなく、 基準となる素子のガ ンマ補正テーブルと、 位置的に隣接する素子のガンマ補正テーブルの差分値を記 憶させることで、 記憶容量を小さくするようにしている。  In the gamma correction apparatus according to the third embodiment, the gamma correction table for each element from the first element to the Nth element is not stored as it is, but the gamma correction table for the element serving as a reference is stored in position. By storing the difference value of the gamma correction table of the adjacent element, the storage capacity is reduced.
ガンマ補正は一般的には、 第 2 7図で示したように、 入力データに対するガン マ捕正値をテーブル形式で R OMに記憶したものを使用して行う。 前述したよう に、 このガンマ捕正テーブルを素子毎に持たせようとすると、 例えば 8ビットの R , G, B 3色で 6 4 0素子分では、  Gamma correction is generally performed using gamma correction values for input data stored in ROM in a table format, as shown in Fig. 27. As described above, if this gamma correction table is to be provided for each element, for example, for 6 elements of 8 bits of R, G, and B colors,
2 8 X 3 X 6 4 0 = 4 9 1 , 5 2 0バイト 2 8 X 3 X 6 4 0 = 49 1, 5 20 bytes
の容量が必要となる。 そこで基準となる素子のガンマ補正テーブルは従来どおり にガンマ補正値を R OMに記憶させるが、 それ以外の素子については位置的に隣 接する素子どうしのガンマ補正テーブルの差分値を記憶することで容量を小さく する。 以下、 この差分値の算出方法について第 1 1図を用いて詳しく説明する。 第 1 1図においてテーブル 1 1 0 1が各素子毎のガンマ補正値を示しており、 1番素子から 4番素子までの入力値に対するガンマ補正値が格納されている。 こ の場合、 1番素子が基準となる素子であり、 1番素子はそのまま 8ビットでガン マ補正値が記憶される。 2番目以降の素子についてはテーブル 1 1 0 2に示すよ うに、 入力値毎に、 位置的に隣接する素子どうしのガンマ補正値の差分値を記憶 していく。 すなわち、 2番素子では、 1番素子との入力値毎の差分値、 3番素子 では 2番素子との入力値毎の差分値というように差分値を記憶していく。 Is required. Thus, the gamma correction table of the reference element stores the gamma correction value in the ROM as before, but for the other elements, the difference is stored by storing the difference value of the gamma correction table between the elements adjacent in position. To be smaller. Hereinafter, a method of calculating the difference value will be described in detail with reference to FIG. In FIG. 11, a table 111 shows gamma correction values for each element, and stores gamma correction values for input values of the first to fourth elements. In this case, element 1 is the reference element and element 1 is 8-bit gun The correction value is stored. For the second and subsequent elements, as shown in Table 1102, for each input value, the difference value of the gamma correction value between elements adjacent in position is stored. That is, the difference value is stored for the second element such as a difference value for each input value with the first element, and for the third element, a difference value for each input value with the second element.
例えば、 2番素子の入力値 1の差分値は、 2番素子ガンマ補正値 1 8と 1番素 子ガンマ補正値 2 1との差分値であるから差分値は一 3 ( 1 8 - 2 1 ) となる。 このようにして差分値を算出すると第 1 1図のテーブル 1 1 0 2に示すような値 となる。  For example, since the difference value of the input value 1 of the second element is the difference value between the second element gamma correction value 18 and the first element gamma correction value 21, the difference value is 1 3 (1 8-2 1 ). When the difference value is calculated in this manner, a value as shown in the table 1102 in FIG. 11 is obtained.
テーブル 1 1 0 2の差分値をみてみると、 隣接する画素どうしの差分であるた め、 素子の特性の差が小さいことにより差分値は元のガンマ捕正値よりかなり小 さい値となる。 第 1 1図の例では、 一 3から 2までの値となる。 これらの数値を 格納するには 3ビットの容量ですむため、 記憶容量を約 3 / 8にすることができ る。 このようにして算出した基準素子ガンマ補正値と差分値とをガンマ補正値記 憶回路 1 0 0 5に記憶する。 この場合、差分値は 3ビットで順次記憶させていく。 このように 1番素子を基準素子とした場合には、 ガンマ補正値記憶回路 1 0 0 5の基準素子ガンマ補正テーブルには、 1番素子のガンマ補正テーブル、 差分値 厶 1には 2番素子と 1番素子の差分値、 差分値 Δ 2には 3番素子と 2番素子との 差分値というようにガンマ補正値が順次記憶される。  Looking at the difference values in Table 1102, they are differences between adjacent pixels, so the difference value is significantly smaller than the original gamma correction value due to the small difference in element characteristics. In the example of Fig. 11, the value is between 1 and 3. Since storing these numerical values requires only 3 bits, the storage capacity can be reduced to about 3/8. The reference element gamma correction value thus calculated and the difference value are stored in the gamma correction value storage circuit 1005. In this case, the difference value is sequentially stored in three bits. When the first element is used as the reference element, the gamma correction table of the gamma correction value storage circuit 1005 has the gamma correction table of the first element and the difference value 1 has the second element. The gamma correction value is sequentially stored as the difference value between the third element and the first element, and the difference value Δ2 as the difference value between the third element and the second element.
次に、 ガンマ補正記憶回路 1 0 0 5からガンマ捕正値を算出し、 ガンマ捕正を 行う方法について述べる。 ガンマ補正値算出回路 1 0 0 4ではガンマ補正記憶回 路 1 0 0 5に記憶してある基準素子ガンマ補正値と差分値とから素子毎のガンマ 補正値を復元する。 この復元方法について第 1 1図を用いながら説明する。  Next, a method of calculating a gamma correction value from the gamma correction storage circuit 1005 and performing gamma correction will be described. The gamma correction value calculation circuit 1004 restores the gamma correction value for each element from the reference element gamma correction value and the difference value stored in the gamma correction storage circuit 1005. This restoration method will be described with reference to FIG.
第 1 1図において、 1番素子が基準素子ガンマ補正テーブルであるから、 素子 選択回路 1 0 6で 1番素子が選択された場合には、 そのまま記憶してあるガンマ 補正値を使用してガンマ補正を行う。 例えば、 入力画像データが 3の場合には入 力値 3に対応する値 3 4を出力データとして出力することによりガンマ捕正を行 うことができる。  In FIG. 11, since the first element is the reference element gamma correction table, when the first element is selected by the element selection circuit 106, the gamma is corrected using the stored gamma correction value. Make corrections. For example, when the input image data is 3, gamma correction can be performed by outputting a value 34 corresponding to the input value 3 as output data.
そして、 2番素子以降は基準素子のガンマ補正値に、 素子位置までの差分値を 積算した値を加算してガンマ補正値を算出し、 ガンマ補正を行う。 例えば、 4番 素子の入力値 0に対応するガンマ捕正値を算出する場合は、 基準となる 1番素子 の入力値 0に対応するガンマ補正値は 0であり、 2番素子の差分値は 1、 3番素 子の差分値は一 1、 4番素子の差分値は 2であるからこれらの数値を積算した値 がガンマ補正値となる。 すなわち、 For the second and subsequent elements, the gamma correction value is calculated by adding the value obtained by integrating the difference value up to the element position to the gamma correction value of the reference element, and the gamma correction is performed. For example, number 4 When calculating the gamma correction value corresponding to the input value 0 of the element, the gamma correction value corresponding to the input value 0 of the first element, which is the reference, is 0, and the difference value of the second element is 1, 3, Since the difference value of the element is 11 and the difference value of the fourth element is 2, the value obtained by integrating these values is the gamma correction value. That is,
(ガンマ補正値） = 0 + 1 + (—1 ) + 2 = 2  (Gamma correction value) = 0 + 1 + (-1) + 2 = 2
というように、 ガンマ補正値が算出される。 第 1 1図のテーブル 1 1 0 1をみて みると、 元々の 4番素子の入力値 0に対応するガンマ補正値は 2であるから、 ガ ンマ補正値を忠実に復元できることがわかる。 同様にして他の素子においても基 準素子のガンマ補正値に素子位置までの差分値を積算した値を加算することによ り、 素子毎のガンマ補正値を算出することができる。 Thus, the gamma correction value is calculated. Looking at the table 111 of FIG. 11, it can be seen that the gamma correction value corresponding to the original input value 0 of the fourth element is 2, so that the gamma correction value can be faithfully restored. Similarly, for other elements, a gamma correction value for each element can be calculated by adding a value obtained by integrating the difference value up to the element position to the gamma correction value of the reference element.
このようにガンマ捕正値算出回路 1 0 0 4では、 基準素子ガンマ補正テープノレ と差分値とから、 素子選択回路 1 0 6にて選択された素子毎にガンマ捕正値を算 出し、 算出した素子毎のガンマ補正値からガンマ補正回路 1 0 3にてガンマ補正 を行うことができる。 '  As described above, the gamma correction value calculation circuit 1004 calculates and calculates the gamma correction value for each element selected by the element selection circuit 106 from the reference element gamma correction tape hole and the difference value. Gamma correction can be performed by the gamma correction circuit 103 from the gamma correction value for each element. '
このように本実施の形態 3によれば、 ガンマ補正記憶回路 1 0 0 5に、 基準素 子のガンマ補正値と、 位置的に隣接する素子どうしのガンマ補正値の差分値を予 め定めた記憶容量で記憶し、 基準素子は記憶してあるガンマ補正値によりガンマ 補正を行い、 それ以外の素子では基準素子のガンマ捕正値に、 素子位置までの差 分値を積算した値からガンマ補正値を算出してガンマ補正を行うようにしたので、 各画素毎にガンマ補正を行うことができ、 画質の劣化を抑えることができるとと もに、 少ない記憶容量で素子毎のガンマ補正データを記憶することができる。 なお、 予め定めた記憶容量で差分値を記憶させる際に、 低階調側では 4ビット で記憶させ、 それ以外の階調では 2ビットで記憶させるというように、 記憶容量 を変えるようにしてもよい。 これは上述したように、 低階調側では素子のガンマ 補正値がばらつきやすいため、 差分値が大きくなり、 この領域の差分値に合わせ て差分値の記憶容量を決めた場合、 それ以外の領域では記憶容量が無駄になる場 合があるためである。 そこで上述のように、 効率よく記憶させるため、 低階調側 とそれ以外で記憶容量を変えるようにしてもよレ、。  As described above, according to the third embodiment, the difference value between the gamma correction value of the reference element and the gamma correction value of the element adjacent in position is predetermined in the gamma correction storage circuit 1005. Gamma correction is performed using the stored gamma correction value for the reference element, and gamma correction is performed for the other elements by integrating the gamma correction value of the reference element with the differential value up to the element position. Since the gamma correction is performed by calculating the value, the gamma correction can be performed for each pixel, which can suppress the deterioration of the image quality and the gamma correction data for each element with a small storage capacity. Can be memorized. When the difference value is stored with a predetermined storage capacity, the storage capacity may be changed such that the lower gray scale side stores it as 4 bits and the other gray scales stores it as 2 bits. Good. This is because, as described above, the gamma correction value of the element tends to fluctuate on the low gradation side, so that the difference value becomes large. This is because storage capacity may be wasted. Therefore, as described above, the storage capacity may be changed between the low gradation side and the rest for efficient storage.
(実施の形態 4 . ) 次に本発明の実施の形態 4によるガンマ補正装置について説明する。 本実施の 形態では、 上述した実施の形態 2と実施の形態 3の構成とを組み合わせた特徴を 有する。すなわち、第 1 2図において、第 4図及び第 1 0図と同一符号は、同一ま たは相当部分を示し、 1 2 0 4は、 ガンマ補正値記憶回路 1 0 0 5から得られた 値をもとに、 ガンマ補正値算出回路 1 0 0 4の出力と、 パターン値記憶回路 4 0 8から出力されたパターン値とを用いて補間処理により適切なガンマ捕正値を算 出するガンマ補正値補間回路である。 (Embodiment 4) Next, a gamma correction device according to Embodiment 4 of the present invention will be described. This embodiment has a feature in which the configurations of the above-described second embodiment and the third embodiment are combined. That is, in FIG. 12, the same reference numerals as those in FIGS. 4 and 10 indicate the same or corresponding parts, and 1204 indicates the value obtained from the gamma correction value storage circuit 1005. Gamma correction that calculates an appropriate gamma correction value by interpolation using the output of the gamma correction value calculation circuit 104 and the pattern value output from the pattern value storage circuit 408 It is a value interpolation circuit.
上記実施の形態 2でも述べたように、 ガンマ補正値記憶回路 1 0 0 5にはグレ 一チャートのパターンに対するガンマ補正値を記憶しておき、 補間処理によりガ ンマ補正値を捕間するようにすれば、 記憶容量を小さくしてガンマ補正を行うこ とができる。 すなわち、 上記ガンマ補正値記憶回路 1 0 0 5にはパターン数分の 基準素子ガンマ補正テーブル値と差分値とが記憶されている。'例えば、第 1 3 ( a ) 図のテーブルに示すようなデータが記憶されている。 ガンマ 正値算出回路 1 0 0 5では前述した方法により、 各素子のガンマ捕正値を算出する。 第 1 3 ' ( a ) 図のテーブルの場合には、 1番素子が基準素子であるから、 2番素子から N番素 子までは基準素子である 1番素子のガンマ補正値に素子位置までの差分値を積算 した値を加算することで、 第 1 3 ( b ) 図に示すテーブルのようにガンマ補正値 を算出することができる。 As described in the second embodiment, the gamma correction value storage circuit 1005 stores the gamma correction value for the gray chart pattern, and interpolates the gamma correction value by interpolation. By doing so, it is possible to perform gamma correction with a small storage capacity. That is, the gamma correction value storage circuit 1005 stores the reference element gamma correction table values and the difference values for the number of patterns. 'For example, data as shown in the first 3 (a) view tables are stored. The gamma positive value calculation circuit 1005 calculates the gamma correction value of each element by the method described above. In the case of the table shown in Fig. 13 '(a), element 1 is the reference element, so elements 2 to N are the reference elements. The gamma correction value can be calculated as shown in the table shown in FIG. 13 (b) by adding up the value obtained by integrating the difference values of.
ガンマ補正値捕間回路 1 2 0 4では、 ガンマ補正値算出回路 1 0 0 5から算出 されたガンマ補正値と、 パターン値記憶回路 4 0 8に記憶してあるパターン値と からガンマ補正値の補間を行う。 この捕間方法については実施の形態 2で述べた 方法に従つて補間処理を行う。  The gamma correction value capturing circuit 1204 calculates the gamma correction value from the gamma correction value calculated from the gamma correction value calculation circuit 1005 and the pattern value stored in the pattern value storage circuit 408. Performs interpolation. With regard to this capturing method, interpolation processing is performed according to the method described in the second embodiment.
このようにしてガンマ補正値補間回路 1 2 0 4にて補間されたガンマ捕正値を もとに、ガンマ補正回路 1 0 3により各素子毎にガンマ補正を行うことができる。 このように本実施の形態によれば、 ガンマ補正記憶回路 1 0 0 5に、 基準素子 のガンマ補正値と、 離散的に記憶させた各素子どうしのガンマ補正値の差分値と を記憶し、 基準素子は記憶してあるガンマ補正値によりガンマ補正を行い、 その 他の素子については、 ガンマ補正値補間回路 1 2 0 4で補間処理により適切なガ ンマ補正値を算出してガンマ補正を行うようにしたので、 各画素毎にガンマ補正 を行うことができ、 画質の劣化を抑えることができるとともに、 より少ない記憶 容量で素子毎のガンマ補正データを記憶することができる。 Gamma correction can be performed for each element by the gamma correction circuit 103 based on the gamma correction value interpolated by the gamma correction value interpolation circuit 124 in this manner. As described above, according to the present embodiment, the gamma correction storage circuit 1005 stores the gamma correction value of the reference element and the difference value of the gamma correction value of each element stored discretely, The reference element performs gamma correction based on the stored gamma correction value, and the other elements perform gamma correction by calculating an appropriate gamma correction value by interpolation processing in the gamma correction value interpolation circuit 124. Gamma correction for each pixel This makes it possible to suppress deterioration in image quality and to store gamma correction data for each element with a smaller storage capacity.
なお、 本実施の形態においても、 ガンマ補正曲線が低階調部での変化が大きい ことから、 この領域でのデータをより多くとることによりガンマ補正精度を向上 させることを目的として、 離散的な入力値に対するガンマ補正値を記憶させる場 合、 低階調部のパターン、 つまり喑ぃ領域のパターンに対するガンマ補正値をよ り多く記憶させるようにしてもよい。  Also in the present embodiment, since the gamma correction curve has a large change in the low gradation area, discrete data is used for the purpose of improving the gamma correction accuracy by taking more data in this area. When the gamma correction value for the input value is stored, more gamma correction values for the pattern of the low gradation part, that is, the pattern of the area 喑 ぃ may be stored.
また、 基準となる素子について 1番目の素子を基準素子としたが、 もちろんど の素子を基準素子としてもよい。  Although the first element is used as a reference element as a reference element, any element may be used as a reference element.
また、基準素子を 1つだけとするのではなく、何点も基準素子をもってもよい。 また、 離散的な入力値に対するガンマ補正値を記憶する場合、 グレーチャート の 1 0パターンを記憶する場合について説明したがパターン数もこれに限定する ものではない。  Also, instead of having only one reference element, any number of reference elements may be provided. Also, the case where the gamma correction value for a discrete input value is stored and the case where 10 patterns of a gray chart are stored has been described, but the number of patterns is not limited to this.
さらに、 ガンマ補正値を補間する場合、 直線近似で補間するのでなく、 '2次曲 線等の曲線により補間するようにしてもよい。  Further, when interpolating the gamma correction value, interpolation may be performed using a curve such as a 'quadratic curve' instead of performing linear approximation.
(実施の形態 5 . )  (Embodiment 5)
以下に、 本発明の実施の形態 5にかかるガンマ補正装置について、 図を参照し ながら説明する。 本実施の形態 5にかかるガンマ補正装置の構成、 並びに基本的 な動作は実施の形態 3と示したものと同じであるが、 ガンマ補正値記億回路 1 0 0 5において、 位置的に隣接する素子どうしのガンマ補正値の差分値をそのまま 記憶するのではなく、 差分値が、 差分値を記憶する容量を超過した場合、 隣接す る次の素子では、 差分値に超過した値を加算した値を差分値として記憶する点が 異なる。 以下、 その動作について詳しく説明する。  Hereinafter, a gamma correction device according to a fifth embodiment of the present invention will be described with reference to the drawings. The configuration and the basic operation of the gamma correction device according to the fifth embodiment are the same as those described in the third embodiment, except that the gamma correction value storage circuit Rather than storing the difference value of the gamma correction values between elements as it is, if the difference value exceeds the capacity to store the difference value, the next adjacent element adds the excess value to the difference value Is stored as a difference value. Hereinafter, the operation will be described in detail.
差分値を記憶する際には、 予め定めた記憶容量に差分値を記憶すると元のガン マ補正値を復元する処理が非常に簡単になる。 しかし予め定めた記憶容量に対し て差分値が大きく、 記憶容量を超過する事態が発生する場合がある。 その場合に は、 差分値をそのまま積算してガンマ補正値を算出したのでは元のガンマ捕正値 を復元することができなくなる。  When the difference value is stored, storing the difference value in a predetermined storage capacity greatly simplifies the process of restoring the original gamma correction value. However, there is a case where the difference value is larger than the predetermined storage capacity and the storage capacity is exceeded. In this case, if the gamma correction value is calculated by integrating the difference value as it is, the original gamma correction value cannot be restored.
例えば、 第 1 4 ( a ) 図のテーブル 1 4 0 1に示すように、 ガンマ捕正値があ る場合、 差分値を 4ビットで記憶する場合について考えると、 素子毎の差分値は 第 1 4図のテーブル 1 4 0 2に示すようになる。 4ビットでは— 8から 7までの 値し力記憶できないため、 例えば、 入力値 1に対応する 1番素子のガンマ補正値 は 1 6、 2番素子のガンマ補正値は 2 6でその差分値は 1 0であるにも係らず、 4ビットを超えるため差分値 7として記憶されてしまう。 For example, as shown in Table 1401 in Fig. 14 (a), the gamma correction value is In the case where the difference value is stored in 4 bits, the difference value for each element is as shown in Table 1402 in FIG. With 4 bits, values from 8 to 7 cannot be stored.For example, the gamma correction value of element 1 corresponding to input value 1 is 16, the gamma correction value of element 2 is 26, and the difference value is 2. Despite being 10, it exceeds 4 bits and is stored as difference value 7.
従って、 第 1 4 ( b ) 図のテーブル 1 4 0 3に示すように、 1番素子を基準と して差分値からガンマ補正値を算出した場合、 2番素子の入力値 1に対応するガ ンマ補正値は、  Therefore, as shown in Table 144 of FIG. 14 (b), when the gamma correction value is calculated from the difference value with reference to the first element, the gas corresponding to the input value 1 of the second element is obtained. The comma correction value is
1 6 + 7 = 2 3 1 6 + 7 = 2 3
となる。 3番素子の入力値 1に対応するガンマ補正値は基準となる 1番素子のガ ンマ補正値に 2番素子の差分値、 3番素子の差分値を加算し 値となるため、 1 6 + 7 + (- 4 ) = 1 9 Becomes The gamma correction value corresponding to the input value 1 of the third element is obtained by adding the difference value of the second element and the difference value of the third element to the reference gamma correction value of the first element. 7 + (-4) = 1 9
となる。 同様に 4番素子の入力値 1に対応するガンマ補正値は 1 7となる。 Becomes Similarly, the gamma correction value corresponding to the input value 1 of the fourth element is 17.
このように差分値が記憶容量を越えた場合、 その超過した値が誤差となり、 そ れ以降の素子に影響を及ぼし、 元のガンマ補正値を復元できなくなる場合があつ た。  When the difference value exceeds the storage capacity in this way, the excess value becomes an error, which may affect subsequent elements and make it impossible to restore the original gamma correction value.
そこで差分値が記憶容量を越えた場合には、 その誤差を次の差分値に加算する ことにより、 誤差が次の素子のガンマ補正値算出に影響しないようにする。  If the difference value exceeds the storage capacity, the error is added to the next difference value so that the error does not affect the gamma correction value calculation of the next element.
前述したように、 2番素子の入力値 1に対応する差分値は 1 0であるが 7まで しか記憶できないため、 3の誤差が生じる。 そこで第 1 5 ( a ) 図のテーブル 1 5 0 2に示すように、 その誤差 3を 3番素子の差分値に加算して記憶させるよう にする。 従って、 元々 3番素子の差分値は一 4であるから、 誤差 3と差分値一 4 を加算した一 1が 3番素子の入力値 1に対応する差分値となる。  As described above, although the difference value corresponding to the input value 1 of the second element is 10 but can only be stored up to 7, an error of 3 occurs. Therefore, as shown in Table 1502 in FIG. 15 (a), the error 3 is added to the difference value of the third element and stored. Therefore, since the difference value of the third element is originally 4, 1 1 which is obtained by adding the error 3 and the difference value of 4 is the difference value corresponding to the input value 1 of the third element.
このようにして算出した差分値をもとにガンマ補正値を復元すると、 第 1 5 ( b ) 図のテーブル 1 5 0 3に示すようになり、 2番素子の入力値 1に対応する ガンマ捕正値は、 差分値の記憶容量を超過しているため誤差を生じるが、 3番素 子の入力値 1に対応するガンマ捕正値は 2 2、 4番素子では 2 0となり、 元のガ ンマ補正値を忠実に復元できることがわかる。 以上のようにして差分値の記憶容 量を越えた場合は、超えた誤差データを次の素子の差分値に加算することにより、 差分値が記憶容量を越えた場合でも、 最小限の誤差でガンマ補正を行うことがで さる。 When the gamma correction value is restored based on the difference value calculated in this way, the result is as shown in Table 1503 in FIG. 15 (b), and the gamma correction value corresponding to the input value 1 of the second element is obtained. Although a positive value causes an error because it exceeds the storage capacity of the difference value, the gamma correction value corresponding to the input value 1 of the third element is 22 and the gamma correction value of the fourth element is 20. It can be seen that the gamma correction value can be faithfully restored. When the difference value exceeds the storage capacity as described above, the excess error data is added to the difference value of the next element, Even when the difference value exceeds the storage capacity, gamma correction can be performed with a minimum error.
このように本実施の形態によれば、 ガンマ補正値記憶回路 1 0 0 5に、 位置的 に隣接する素子どうしのガンマ捕正値の差分値を記憶する際に、 差分値が、 差分 値を記憶する容量を超過した場合、 隣接する次の素子において、 差分値に超過し た値を加算した値を差分値として記憶するようにしたから、 少ない記憶容量で素 子毎にガンマ補正を行うことができると共に、 差分値が差分値を記億する容量を 超過した場合でもその誤差を最小限に抑えることができる。  As described above, according to the present embodiment, when the gamma correction value storage circuit 1005 stores the difference value of the gamma correction value between the elements that are adjacent in position, the difference value When the storage capacity is exceeded, the difference value is added to the difference value in the next adjacent element, and the difference value is stored as the difference value.Therefore, gamma correction must be performed for each element with a small storage capacity. When the difference value exceeds the capacity for storing the difference value, the error can be minimized.
なお、 本実施の形態においても、 素子特性補正値テーブルに上記実施の形態 2 でも述べたように、 連続した入力データに対するガンマ補正値を記憶させるので はなく、 離散的な入力データに対するガンマ補正値を記憶するようにすることに より、 記憶容量をさらに小さくすることができる。  In this embodiment, the gamma correction values for the continuous input data are not stored in the element characteristic correction value table, as described in the second embodiment, but the gamma correction values for the discrete input data are stored. By storing the data, the storage capacity can be further reduced.
また、 上記離散的な入力値に対するガンマ補正値を記憶きせる場合、 低階調部 のパターン、 つまり暗い領域のパターンに対するガンマ補正値をより多く記憶さ せることで、 低階調部でのガンマ捕正曲線の変化が大きい領域でのガンマ補正精 度を向上させることができる。  When the gamma correction value for the discrete input value can be stored, the gamma correction value for the low gradation part pattern, that is, the pattern in the dark area is stored more, so that the gamma correction in the low gradation part is stored. Gamma correction accuracy can be improved in a region where the change of the positive curve is large.
また、 基準となる素子について 1番目の素子を基準素子としたが、 もちろんど の素子を基準素子としてもよい。  Although the first element is used as a reference element as a reference element, any element may be used as a reference element.
さらに、 また、 基準素子を 1つだけとするのではなく、 何点も基準素子をもつ ていてもよい。  Further, instead of having only one reference element, any number of reference elements may be provided.
(実施の形態 6 . )  (Embodiment 6)
以下に本発明の実施の形態 6にかかるガンマ捕正装置について、 図を参照しな がら説明する。 第 1 6図は本実施の形態 6のガンマ補正装置の構成を示すブロッ ク図である。 第 1 6図において、 第 1図と同一符号は同一、 または相当部分を示 し、 1 6 0 4は、 素子のガンマ補正値の平均値と、 その平均値と各素子毎のガン マ補正値の差分値を記憶したガンマ補正値記憶回路 1 6 0 5から出力される値を 基にガンマ補正値を算出するガンマ補正値算出回路である。  Hereinafter, a gamma correction device according to a sixth embodiment of the present invention will be described with reference to the drawings. FIG. 16 is a block diagram showing the configuration of the gamma correction device according to the sixth embodiment. In FIG. 16, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and 1604 denotes the average value of the gamma correction values of the elements, and the average value and the gamma correction value of each element. This is a gamma correction value calculation circuit that calculates a gamma correction value based on the value output from the gamma correction value storage circuit 1605 that stores the difference value of.
本実施の形態では、 上記実施の形態 3〜 5で説明したように、 基準素子との差 分値を記憶するのではなく、素子毎のガンマ補正値の平均値との差分値を記憶し、 ガンマ捕正を行うことを特徴としている。 In the present embodiment, as described in Embodiments 3 to 5, instead of storing the difference value from the reference element, the difference value from the average value of the gamma correction value for each element is stored, It is characterized by performing gamma correction.
すなわち、 ガンマ補正値記憶回路 1 6 0 5には、 入力値毎のガンマ捕正値の平 均値と、 各素子毎のガンマ補正値と上記平均値との差分値を算出して記憶する。 例えば、 素子毎のガンマ補正値が第 1 7 ( a ) 図のテ一ブノレ 1 7 0 1に示すよう な場合には、 平均値とその平均値に対する差分値は第 1 7 ( b ) 図のテーブル 1 7 0 2に示すように算出される。 例えば、 入力値 1に対する各素子のガンマ補正 値の平均値が 2 1の場合には、 1番素子のガンマ補正値は 1 6であるから、 その 差分値一 5が差分値として記憶される。 同様に 2番素子では 5が差分値として記 憶され、 3番素子では 1、 4番素子では— 1が差分値として記憶される。 このよ うに平均値と差分値とを算出してガンマ補正値記憶回路 1 6 0 5に記憶する。 従って、 ガンマ補正値記憶回路 1 6 0 5の平均値データには入力値毎の平均値 が記憶され、 差分値 Δ 1には 1番素子の差分値、 差分値 Δ 2には 2番素子の差分 値というように記憶される。 このように平均値との差分値 ガンマ捕正値として 記憶させることで、 記憶容量を小さくすることができる。  That is, the gamma correction value storage circuit 1605 calculates and stores the average value of the gamma correction value for each input value and the difference value between the gamma correction value for each element and the average value. For example, if the gamma correction value for each element is as shown in Table 1701 in Fig. 17 (a), the average value and the difference value with respect to the average value are as shown in Fig. 17 (b). It is calculated as shown in Table 1702. For example, when the average value of the gamma correction values of the respective elements with respect to the input value 1 is 21, the gamma correction value of the first element is 16, and the difference value 15 is stored as the difference value. Similarly, 5 is stored as the difference value for the second element, 1 is stored for the third element, and -1 is stored as the difference value for the fourth element. In this way, the average value and the difference value are calculated and stored in the gamma correction value storage circuit 1605. Therefore, the average value of each input value is stored in the average value data of the gamma correction value storage circuit 165, and the difference value Δ1 is the difference value of the first element, and the difference value Δ2 is the second element. It is stored as a difference value. By storing the difference value from the average value as the gamma correction value, the storage capacity can be reduced.
そして、 ガンマ捕正値算出回路 1 6 0 4では、 ガンマ捕正値記憶回路 1 6 0 5 に記憶してある平均値データと差分値から素子選択回路 1 6 0 6にて選択された 素子のガンマ補正値を算出する。 例えば、 1番素子では平均値データに差分値 Δ 1を加算することによりガンマ補正テーブルを作成し、 2番素子では平均値デー タに差分値 Δ 2を加算してガンマ捕正テーブルを作成することができる。  Then, in the gamma correction value calculation circuit 1604, the element selected by the element selection circuit 1606 from the average value data and the difference value stored in the gamma correction value storage circuit 1605. Calculate the gamma correction value. For example, the first device creates a gamma correction table by adding the difference value Δ1 to the average value data, and the second device creates a gamma correction table by adding the difference value Δ2 to the average value data. be able to.
このように平均値と、 平均値との差分値を記憶させる方法では平均値と素子毎 のガンマ補正値の差が大きい場合には記憶容量が多少大きくなるが、 各素子の差 分値が独立して記憶されているため、 差分値がその記憶容量を超過する場合、 そ の誤差が他の素子のガンマ補正に影響を及ぼさないという利点がある。  As described above, in the method of storing the difference between the average value and the average value, when the difference between the average value and the gamma correction value of each element is large, the storage capacity is slightly increased, but the difference value of each element is independent. When the difference value exceeds the storage capacity, the error does not affect the gamma correction of other elements.
このように本実施の形態によれば、 ガンマ補正値記憶回路 1 6 0 5に、 素子の ガンマ補正値の平均値と、 その平均値と各素子毎のガンマ補正値の差分値を記憶 し、 ガンマ補正値算出回路 1 6 0 4において、 上記ガンマ捕正値記憶回路 1 6 0 5より出力される、 上記ガンマ補正値の平均値と、 該平均値と各素子毎のガンマ 捕正値の差分値とを用いて、 各素子毎にガンマ補正値の平均値に素子毎の差分値 を加算した値からガンマ補正値を算出し、 ガンマ捕正回路 1 0 6によってガンマ 補正を行うようにしたから、 素子毎に独立して平均値に差分値を加算してガンマ 補正値を算出するため正確にガンマ補正を行えるとともに、 各素子の差分値が独 立して記憶されているため、 差分値がその記憶容量を超過する場合、 その誤差が 他の素子のガンマ補正に影響を与えることがない。 As described above, according to the present embodiment, the average value of the gamma correction values of the elements and the difference value between the average value and the gamma correction value of each element are stored in the gamma correction value storage circuit 1605. In the gamma correction value calculation circuit 1604, the average value of the gamma correction values output from the gamma correction value storage circuit 1605, and the difference between the average value and the gamma correction value of each element The gamma correction value is calculated from the value obtained by adding the difference value for each element to the average value of the gamma correction values for each element using the values and the gamma correction circuit 106. Since the correction is performed, the gamma correction value is calculated by independently adding the difference value to the average value for each element, so that gamma correction can be performed accurately and the difference value of each element is stored independently. Therefore, if the difference value exceeds its storage capacity, the error does not affect the gamma correction of other elements.
なお、 上記ガンマ補正値記憶回路 1 6 0 5には、 上記実施の形態 2でも述べた ように、 連続した入力データに対するガンマ捕正値を記憶させるのではなく、 離 散的な入力値に対するガンマ補正値を記憶するようにすると記憶容量を小さくす ることができる。  Note that, as described in the second embodiment, the gamma correction value storage circuit 1605 does not store the gamma correction values for continuous input data, but instead stores gamma correction values for discrete input values. If the correction value is stored, the storage capacity can be reduced.
また、 その場合、 低階調領域すなわち暗い領域のデータをより多く記憶させ、 低階調部でのガンマ補正曲線の変化が大きい領域でのガンマ捕正値をより正確に 復元するようにして、 ガンマ補正の精度を向上させるようにしてもよい。  In that case, more data is stored in the low gradation area, that is, in the dark area, and the gamma correction value in the area where the change in the gamma correction curve is large in the low gradation area is more accurately restored. The accuracy of gamma correction may be improved.
(実施の形態 7 . )  (Embodiment 7)
以下に、 本発明の実施の形態 7にかかるガンマ捕正装置について、 図を参照し ながら説明する。 第 1 8図は本実施の形態 7のガンマ補正装置の構成を示すプロ ック図である。 第 1 8図において、 第 1 0図と同一符号は同一、 または相当部分 を示し、 1 8 0 4は、 差分値のデータ長を一緒に記憶させたガンマ補正値記憶回 路 1 8 0 5の出力を受けてガンマ補正値を算出するガンマ補正値算出回路である。 基本的な動作は実施の形態 3で述べたのと同じであるが、 差分値を予め定めた 記憶容量に記憶させるのではなく、 差分値の大きさに合わせてその記憶容量を変 化させる点が異なる。 以下、 その動作について詳しく説明する。  Hereinafter, a gamma correction device according to a seventh embodiment of the present invention will be described with reference to the drawings. FIG. 18 is a block diagram showing the configuration of the gamma correction device according to the seventh embodiment. In FIG. 18, the same reference numerals as those in FIG. 10 denote the same or corresponding parts, and 1804 denotes a gamma correction value storage circuit 1805 in which the data length of the difference value is stored together. This is a gamma correction value calculation circuit that calculates a gamma correction value by receiving an output. The basic operation is the same as that described in the third embodiment, except that the difference value is not stored in a predetermined storage capacity, but the storage capacity is changed according to the magnitude of the difference value. Are different. Hereinafter, the operation will be described in detail.
実施の形態 5でも述べたように、 位置的に隣接する素子どうしのガンマ補正値 の差分値を算出した場合、 その差分値は様々な値をとるため、 ある一定の記憶容 量に差分値を記憶させることが不都合な場合がある。 そこで差分値の大きさによ り、記憶容量を変化させることにより、柔軟に差分値を記憶させることができる。 その際に差分値のデータ長を一緒に記憶させることで、 正確にガンマ捕正値を復 元することができる。  As described in the fifth embodiment, when the difference value of the gamma correction value between the elements adjacent in position is calculated, the difference value takes various values, so that the difference value is stored in a certain storage capacity. It may be inconvenient to memorize. Therefore, by changing the storage capacity according to the magnitude of the difference value, the difference value can be flexibly stored. At that time, by storing the data length of the difference value together, the gamma correction value can be accurately restored.
例えば、 第 1 9 ( a ) 図のテーブルに示すように、 1番素子と 2番素子のガン マ捕正値がある場合、 2番素子の差分値が第 1 9 ( b ) 図のテーブルに示すよう に算出される。 その差分値をデータ長と差分値で、 第 2 0図に示すように順次記 憶していく。 第 2 0図の場合には、 データ長を 3ビットで記億し、 その次に差分 値を記憶している。 For example, as shown in the table of Fig. 19 (a), if there is a gamma correction value of the first element and the second element, the difference value of the second element is shown in the table of Fig. 19 (b). It is calculated as shown. The difference value is sequentially recorded as a data length and a difference value as shown in FIG. I will remember. In the case of Fig. 20, the data length is stored in 3 bits, and then the difference value is stored.
デ一タ長は差分値が 1ビットの場合は 0、 2ビットの場合 1、 8ビットの場 合は 7、 というように記憶することでデータ長を 3ビットで記憶できる。 たとえ ば入力値 0に対応する 2番素子の差分値は 0であり、 1ビットで表現できるため データ長が 0として記憶される。 次に入力値 1に対応する差分値は 1 0であり、 5ビットで表現できるため、 データ長が 4として記憶される。 このようにして算 出したデータ長と差分値を第 2 1図に示すように順次記憶していく。  The data length can be stored in 3 bits by storing the data length as 0 if the difference value is 1 bit, 1 if the difference value is 2 bits, 7 if the difference value is 8 bits, and so on. For example, the difference value of the second element corresponding to the input value 0 is 0, and can be represented by 1 bit, so that the data length is stored as 0. Next, since the difference value corresponding to the input value 1 is 10 and can be expressed by 5 bits, the data length is stored as 4. The calculated data length and difference value are sequentially stored as shown in FIG.
このようにデータ長と差分値を順次記憶させることで、 差分値が大きくなつた 場合でも、 正確に差分値を記憶することができるので、 より柔軟に差分値を記憶 することができる。  By sequentially storing the data length and the difference value in this way, even if the difference value becomes large, the difference value can be stored accurately, and thus the difference value can be stored more flexibly.
このように本実施の形態によれば、データ長と差分値を順次記憶させることで、 差分値が大きくなつた場合でも、 正確に差分値を記憶することができ、 差分値の 大きさに合わせて効率良く記憶させることができる。  As described above, according to the present embodiment, by sequentially storing the data length and the difference value, even when the difference value becomes large, the difference value can be accurately stored, and the difference value can be adjusted according to the size of the difference value. Can be stored efficiently.
なお、 ガンマ捕正値記憶回路 1 8 0 5に、 実施の形態 2でも述べたように、 連 続した入力データに対するガンマ補正値を記憶させるのではなく、 離散的な入力 値に対するガンマ補正値を記憶するようにすると記憶容量を小さくすることがで さる。  Note that, as described in the second embodiment, the gamma correction value storage circuit 1805 does not store the gamma correction value for the continuous input data, but stores the gamma correction value for the discrete input value. If the information is stored, the storage capacity can be reduced.
また、 その場合、 低階調領域すなわち暗い領域のデータをより多く記憶させる ようにすると、 ガンマ補正値をより正確に復元することができるので、 ガンマ補 正の精度を向上させることができる。  Also, in this case, if more data is stored in the low gradation area, that is, in the dark area, the gamma correction value can be restored more accurately, so that the accuracy of gamma correction can be improved.
(実施の形態 8 . )  (Embodiment 8)
以下に、 本発明の実施の形態 8にかかるガンマ補正装置について、 図を参照し ながら説明する。 第 2 2図は本実施の形態 8のガンマ捕正装置の構成を示すプロ ック図である。 第 2 2図において、 2 2 0 4はガンマ捕正テーブル選択回路であ り、 複数のガンマ補正テーブルからなるガンマ補正テーブル記憶回路 2 2 0 6の 出力と、 各素子に対応するガンマ捕正テーブルの番号を記録したガンマ選択値記 憶回路 2 2 0 5の出力とから、 所定のデータを選択するものである。  Hereinafter, the gamma correction device according to the eighth embodiment of the present invention will be described with reference to the drawings. FIG. 22 is a block diagram showing a configuration of the gamma correction device according to the eighth embodiment. In FIG. 22, reference numeral 2204 denotes a gamma correction table selection circuit, which includes an output of a gamma correction table storage circuit 222 composed of a plurality of gamma correction tables, and a gamma correction table corresponding to each element. The predetermined data is selected from the output of the gamma selection value storage circuit 222 in which the number of the gamma is recorded.
本実施の形態では、 予めガンマ補正テーブルを複数用意しておき、 素子毎にい ずれかのガンマ捕正テーブルを選択することでガンマ補正値の記憶容量を小さく するようにしたものである。 例えば、 ガンマ捕正テ一ブノレ記憶回路 2 2 0 6に N 個のガンマ捕正テーブルを記憶しておく。 各々のガンマ補正テーブルには番号を 付けておき、 各素子毎にその番号でガンマ補正テーブルを選択し、 選択したガン マ捕正テーブルからガンマ補正を行うように構成する。 In the present embodiment, a plurality of gamma correction tables are prepared in advance, and The storage capacity of the gamma correction value is reduced by selecting a certain gamma correction table. For example, the gamma correction table storage circuit 222 stores N gamma correction tables. A number is assigned to each gamma correction table, a gamma correction table is selected by the number for each element, and gamma correction is performed from the selected gamma correction table.
上記ガンマ選択値記憶回路 2 2 0 5には、 ガンマ補正テ一プルを選択するため の選択番号を素子毎に記憶しておく。 例えば、 1番素子がガンマ補正テーブル 3 を選択する場合、 選択番号 3を 1番素子テーブル選択番号としてガンマ選択値記 憶回路 2 2 0 5に記憶するようにする。  The gamma selection value storage circuit 222 stores a selection number for selecting a gamma correction tape for each element. For example, when the first element selects the gamma correction table 3, the selection number 3 is stored in the gamma selection value storage circuit 222 as the first element table selection number.
ガンマ補正テーブル選択回路 2 2 0 4では、 該当する素子のガンマ補正テープ ルをガンマ選択値記憶回路 2 2 0 5の選択番号を参照してガンマ補正テーブル記 憶回路 2 2 0 6から選択する。 そして、 ガンマ補正回路 1 0 3では、 選択したガ ンマ捕正テーブルをもとにガンマ補正を行う。  The gamma correction table selection circuit 222 selects the gamma correction table of the corresponding element from the gamma correction table storage circuit 222 with reference to the selection number of the gamma selection value storage circuit 222. Then, the gamma correction circuit 103 performs gamma correction based on the selected gamma correction table.
このように予めガンマ捕正テーブルを複数用意しておき、 各素子毎に使用する ガンマ補正テーブルを設定しておくことで、 全体としての記憶容量を小さくする ことができる。 例えば、 6 4 0素子分のガンマ補正テーブルを用意する場合、 す ベての素子のガンマ補正テーブルを個別に用意すると 6 4 0テープル必要となる 力 6 4 0素子の中には、 互いに類似したガンマ特性をもつ素子もあるので、 1 0 0個のガンマ捕正テーブルでよいとすると、 1 0 0 / 6 4 0の容量でガンマ補 正テーブルを記憶できることになる。 なお、 この場合、 ガンマ選択値記憶回路 2 2 0 5の容量については、 これは小さいので無視できる。  By preparing a plurality of gamma correction tables in advance and setting a gamma correction table to be used for each element in this way, the overall storage capacity can be reduced. For example, when preparing gamma correction tables for 640 elements, if the gamma correction tables for all elements are prepared individually, the force required for 640 staples Since some devices have gamma characteristics, if 100 gamma correction tables are sufficient, the gamma correction table can be stored with a capacity of 100/6640. In this case, since the capacity of the gamma selection value storage circuit 222 is small, it can be ignored.
また、 この場合、 スキャナ本体の R OMにはガンマ選択テ一ブルのみ （ガンマ 選択値記憶回路 2 2 0 5 ) を記憶させるようにして、 パソコン側にガンマ補正テ 一ブル （ガンマ補正テーブル記憶回路 2 2 0 6 ) を持たせる構成にしてもよレ、。 これはスキャナ本体の R OMには容量に制限があるが、 パソコン側に記憶させる 場合には、 スキャナ本体の R OMと比較して遥かに大きい記憶容量を用意するこ とができるためである。 このようにパソコン側に捕正テープノレを持たせることに より、 イメージスキャナの R OM容量を小さくすると同時に、 より多くのガンマ 捕正テーブルを記憶することができる。 各素子毎のテーブル選択番号は、 まず、 素子毎の正確なガンマ補正テーブルを 算出し、 そのガンマ補正テーブルと、 予めガンマ補正テーブル記憶回路 2 2 0 6 に用意してあるガンマ捕正テーブルとの最小二乗和差が最も小さくなるガンマ捕 正テ一ブルを選択し、 その選択番号をガンマ選択テーブルに記憶することで正確 にガンマ捕正テーブ^/レを選択することができる。 In this case, only the gamma selection table (gamma selection value storage circuit 222) is stored in the ROM of the scanner body, and the gamma correction table (gamma correction table storage circuit) is stored in the personal computer. 2 2 0 6). This is because the ROM of the scanner itself has a limited capacity, but when storing it on the personal computer side, a much larger storage capacity can be prepared compared to the ROM of the scanner itself. By providing a correction tape in the PC, the ROM capacity of the image scanner can be reduced and more gamma correction tables can be stored. First, an accurate gamma correction table for each element is calculated, and the table selection number for each element is calculated by comparing the gamma correction table with the gamma correction table prepared in the gamma correction table storage circuit 222 in advance. By selecting the gamma correction table that minimizes the least square sum difference and storing the selection number in the gamma selection table, the gamma correction table can be selected accurately.
また、 第 2 3図に示すように、 ガンマ補正テーブル記憶回路 2 3 0 7には、 基 準となる基準ガンマ補正テーブルと、 各ガンマ補正テーブルと基準ガンマ補正テ 一ブルとの差分値を記憶するようにしてもよい。 差分値を記憶することで、 ガン マ補正テーブル 2 3 0 7の記憶容量をさらに小さくすることができる。 基準とな るガンマ補正テーブルには、 ガンマ補正量の最も小さいガンマ補正テーブルを選 択するようにする。 その場合、 ガンマ補正テーブルをガンマ捕正量の小さい順番 に並べ、 ガンマ補正テーブルの差分値を算出するようにする。 従って、 ガンマ補 正テーブル 2 3 0 7の差分値 Δ 1には、 2番目にガンマ補正量の小さいガンマ補 正テーブルと、 最もガンマ補正量の小さレ、ガンマ捕正テーブルとの差分値が記憶 され、 差分値 Δ 2には、 3番目にガンマ補正量の小さいガンマ補正テーブルと、 As shown in FIG. 23, the gamma correction table storage circuit 2307 stores a reference gamma correction table serving as a reference and a difference value between each gamma correction table and the reference gamma correction table. You may make it. By storing the difference value, the storage capacity of the gamma correction table 2307 can be further reduced. As the reference gamma correction table, select the gamma correction table with the smallest gamma correction amount. In this case, the gamma correction table is arranged in the order of the smaller gamma correction amount, and the difference value of the gamma correction table is calculated. Therefore, the difference value Δ1 of the gamma correction table 2307 stores the difference value between the gamma correction table having the second smallest gamma correction amount and the gamma correction table having the smallest gamma correction amount. The difference value Δ 2 has a gamma correction table having the third smallest gamma correction amount,
2番目にガンマ補正量の小さいガンマ補正テーブルとの差分値が記憶される、 と いうように記憶されていく。 The difference value with the gamma correction table having the second smallest gamma correction amount is stored.
また、 反対に、 基準となるガンマ補正テーブルには、 ガンマ捕正量の最も大き いガンマ補正テーブルを選択するようにし、 ガンマ補正量が大きい順番にガンマ 補正テーブルを並べた場合に順番が隣り合うガンマ補正テーブルのガンマ補正値 の差分値を記憶していくようにしてもよい。 - ガンマ補正値算出回路 2 3 0 6では、 基準ガンマ補正テーブルに差分値を積算 することによりガンマ捕正テーブルを算出することができる。 これについては実 施の形態 3で述べた方法と同じである。 例えば、 ガンマ補正量が小さい順番にガ ンマ捕正テーブルが記憶されている場合、 4番目にガンマ補正量の小さいガンマ 補正テーブルは、 基準ガンマ補正テーブルに差分値 Δ 1、 差分値 Δ 2、 差分値 Δ Conversely, for the reference gamma correction table, the gamma correction table with the largest gamma correction amount is selected, and when the gamma correction tables are arranged in descending order of the gamma correction amount, the order is adjacent. The difference value of the gamma correction value in the gamma correction table may be stored. -The gamma correction value calculation circuit 2306 can calculate the gamma correction table by integrating the difference value with the reference gamma correction table. This is the same as the method described in the third embodiment. For example, if the gamma correction tables are stored in ascending order of the gamma correction amount, the fourth gamma correction table with the smallest gamma correction amount will be the difference value Δ1, difference value Δ2, difference value Value Δ
3を力 Β算した値となる。 3 is calculated.
このようにしてガンマ補正テープノレの差分値を記憶することで、 記憶容量を小 さくすることができる。 このように本実施の形態によれば、 予め複数のガンマ補正テーブルをガンマ補 正テーブル記憶回路 2 2 0 6に記憶させておき、 ガンマ選択値記憶回路 2 2 0 5 に、 素子毎にそのガンマ捕正テーブルの選択情報を記憶させ、 ガンマ捕正テープ ル選択回路 2 2 0 4を用いて、 該当するガンマ選択値記憶回路 2 2 0 5に記憶さ れたテープノレ番号に相当するガンマ捕正テーフ レを選択することにより、 小さレ、 記憶容量で素子毎のガンマ補正を行うことができる。 By storing the difference value of the gamma correction tape in this manner, the storage capacity can be reduced. As described above, according to the present embodiment, a plurality of gamma correction tables are stored in the gamma correction table storage circuit 222 in advance, and the gamma correction values are stored in the gamma selection value storage circuit 222 for each element. The selection information of the correction table is stored, and the gamma correction table selection circuit 222 is used to store the gamma correction table corresponding to the tape number stored in the corresponding gamma selection value storage circuit 222. By selecting the gamma, gamma correction can be performed for each element with a small size and storage capacity.
さらに、 上記構成において、 ガンマ補正テーブル記憶回路 2 3 0 7には、 基準 となる基準ガンマ捕正テーブルと、 各ガンマ補正テーブルと基準ガンマ捕正テー ブルとの差分値を記憶することにより、 ガンマ補正テーブルを記憶する容量をさ らに低減することができる。  Further, in the above configuration, the gamma correction table storage circuit 2307 stores a reference gamma correction table serving as a reference, and a difference value between each gamma correction table and the reference gamma correction table. The storage capacity of the correction table can be further reduced.
(実施の形態 9 · )  (Embodiment 9)
以下に、 本発明の実施の形態 9にかかるガンマ補正装置に いて、 図を参照し ながら説明する。  Hereinafter, a gamma correction device according to a ninth embodiment of the present invention will be described with reference to the drawings.
第 2 4図は本実施の形態 9のガンマ補正装置の構成を示すプロック図である。 第 2 4図において、 2 4 0 4は後述する素子特性補正値算出回路 2 4 0 5より出 力される特性補正値を基にガンマ捕正値を算出するガンマ補正値算出回路、 2 4 0 5は後述する素子特性捕正値記憶回路 2 4 0 6に記憶されている基準素子特性 補正テーブルに、 当該素子位置までの差分値を積算した値を加算することにより 選択された素子の特性補正値を算出する素子特性捕正値算出回路、 2 4 0 6はガ ンマ補正を行う前の素子の入力値に対する出力特性補正値を記憶する素子特性補 正値記憶回路である。  FIG. 24 is a block diagram showing the configuration of the gamma correction device according to the ninth embodiment. In FIG. 24, reference numeral 2404 denotes a gamma correction value calculation circuit for calculating a gamma correction value based on a characteristic correction value output from an element characteristic correction value calculation circuit 2405 described later; Reference numeral 5 denotes a characteristic correction of the element selected by adding a value obtained by integrating the difference value up to the element position to a reference element characteristic correction table stored in an element characteristic correction value storage circuit 2406 described later. An element characteristic correction value calculation circuit for calculating a value, and an element characteristic correction value storage circuit 2404 stores an output characteristic correction value corresponding to an input value of the element before performing gamma correction.
基本的な動作は上述した実施の形態 3と同じであるが、 ガンマ補正テーブルを 記憶するのではなく、 ガンマ補正を行う前の素子の入力値に対する出力特性捕正 値である素子特性補正値を記憶させるようにした点が異なる。  The basic operation is the same as that of the third embodiment described above. However, instead of storing the gamma correction table, an element characteristic correction value that is an output characteristic correction value for an input value of an element before performing gamma correction is obtained. The difference is that they are stored.
理想的な素子のガンマ捕正前の特性は、 第 2 5図に示すように、 入力データに 対してリニアな特性となる。 実際の素子の特^1生は第 2 5図に示すようにリニアな 特性からずれている。 そこで理想特性からのずれを補正するための特性補正値を 記憶して特性を補正し、補正された特性値に対して一律のガンマ補正処理を行う。 このようにガンマ補正前の特性補正値を記憶する場合、 ガンマ補正値を記憶す る場合と比較して、 素子毎の差分値を小さくすることができる。 これはガンマ捕 正を行った場合、 低階調部で特"生が大きく変化するため素子毎の特性のばらつき が大きくなる力 ガンマ補正前の素子特性は入力値に対する出力値がほぼリニア な特性になるため、 大きく特性が変化することがなく、 素子毎の差分値を小さく することができるからである。 The characteristics of the ideal element before gamma correction are linear with respect to the input data, as shown in Fig. 25. JP ^ 1 Raw actual elements are offset from the linear characteristic as shown in the second 5 FIG. Therefore, the characteristic correction value for correcting the deviation from the ideal characteristic is stored to correct the characteristic, and a uniform gamma correction process is performed on the corrected characteristic value. When storing the characteristic correction value before gamma correction in this way, the gamma correction value is stored. The difference value for each element can be reduced as compared with the case where This is the characteristic that when the gamma correction is performed, the characteristics of each element greatly vary in the low-gradation area due to a large change in characteristics. The element characteristics before gamma correction are such that the output value with respect to the input value is almost linear. Therefore, the characteristics do not change significantly, and the difference value for each element can be reduced.
例えば、素子毎の特性補正値は第 2 6図のテーブル 2 6 0 1に示すようになり、 入力値に対してほぼリニアな値となる。 従って位置的に隣接する素子どうしの差 分値も第 2 6図のテーブル 2 6 0 2に示すようになり、 ガンマ補正値の差分値を とる場合と比較して、差分値をより小さくすることができる。第 2 6図の例では、 差分値が一 2から 1の間の値であり、 2ビットで差分値が表現できるようになる ため、 ガンマ補正値の記憶容量を約 2 Z 8にすることができる。  For example, the characteristic correction value for each element is as shown in Table 2601 in FIG. 26, and is a value that is almost linear with respect to the input value. Therefore, the difference between the elements adjacent in position is also as shown in Table 260 of FIG. 26, and it is necessary to make the difference smaller than when the difference of the gamma correction value is obtained. Can be. In the example of Fig. 26, the difference value is a value between 1 and 2 and the difference value can be expressed with 2 bits, so the storage capacity of the gamma correction value can be set to about 2Z8. it can.
上記素子特性補正値記憶回路 2 4 0 6には、 差分値から元の特性補正値を算出 する際に基準となる基準素子特性補正テーブルと、 位置的に隣接する素子の特性 補正値の差分値を順番に記憶しておく。 第 2 6図に示した例では、 基準素子特性 捕正テーブルには 1番素子の素子特性補正テーブルを記憶し、 差分値 Δ 1には 2 番素子と 1番素子の素子特性の差分値を記憶し、 差分値 Δ 2には 3番素子と 2番 素子の素子特性の差分値、 というように隣接する差分値を予め定めた記憶容量で 記憶する。  The element characteristic correction value storage circuit 2406 stores a reference element characteristic correction table that is used as a reference when calculating the original characteristic correction value from the difference value, and a difference value between the characteristic correction values of the elements adjacent in position. Are stored in order. In the example shown in Fig. 26, the element characteristic correction table of the first element is stored in the reference element characteristic correction table, and the difference value Δ1 is the difference value between the element characteristics of the second element and the first element. The difference value Δ2 stores the adjacent difference value such as the difference value of the element characteristics between the third element and the second element with a predetermined storage capacity.
素子特性補正値算出回路 2 4 0 5では上記実施の形態 3で説明したように、 素 子選択回路 2 4 0 7にて選択された素子の特性補正値を、 素子特性補正値記憶回 路 2 4 0 6に記憶されている基準素子特性補正テーブルに素子位置までの差分値 を積算した値を加算することにより算出する。  As described in the third embodiment, the element characteristic correction value calculation circuit 2405 stores the element characteristic correction value of the element selected by the element selection circuit 2407 in the element characteristic correction value storage circuit 2. It is calculated by adding a value obtained by integrating the difference values up to the element position to the reference element characteristic correction table stored in 406.
そして、 ガンマ捕正値算出回路 2 4 0 4では、 上記素子特性補正値算出回路 2 4 0 5にて算出された素子毎の特性補正値に対して、 出力モニタの特性に合わせ たガンマ補正値を算出する。  Then, the gamma correction value calculating circuit 2404 compares the gamma correction value corresponding to the output monitor characteristics with the characteristic correction value for each element calculated by the element characteristic correction value calculating circuit 2405. Is calculated.
例えば、 ガンマ値 2 . 2のモニタに表示する場合には、 その逆数の 0 . 4 5の ガンマ特性となるようにガンマ補正値を算出する。 その場合の入力値に対するガ ンマ捕正値は、  For example, when displaying on a monitor with a gamma value of 2.2, a gamma correction value is calculated so that the reciprocal of the gamma characteristic is 0.45. The gamma correction value for the input value in that case is
(ガンマ補正値） = (入力値） 。' 4 5 となる。 このようにガンマ補正値算出回路 2 4 0 4では素子毎のガンマ補正値を 算出し、 ガンマ補正値をガンマ補正回路 2 4 0 3に出力する。 ガンマ補正回路 1 0 3ではこれまで述べた実施の形態と同様に、 素子毎のガンマ捕正値を元にガン マ補正を行う。 (Gamma correction value) = (input value). ' 4 5 Becomes As described above, the gamma correction value calculation circuit 2404 calculates the gamma correction value for each element, and outputs the gamma correction value to the gamma correction circuit 2403. The gamma correction circuit 103 performs gamma correction based on the gamma correction value for each element, as in the above-described embodiments.
このように本実施の形態によれば、 ガンマ補正前の素子特性捕正値を記憶させ ることにより、 少ない記憶容量で素子毎のガンマ補正を行うことができる。 なお、 上記差分値を記憶する際に、 実施の形態 5で述べたように、 位置的に隣 接する素子どうしの特性補正値の差分値をそのまま記憶するのではなく、 差分値 が差分値を記憶する容量を超過した場合、 隣接する次の素子では差分値に超過し た値を加算した値を差分値として記憶するようにしてもよい。 このように超過し た値を次の素子の差分値に加算することにより誤差を最小限にしてデータを復元 することができる。  As described above, according to the present embodiment, the gamma correction for each element can be performed with a small storage capacity by storing the element characteristic correction value before the gamma correction. When storing the difference value, as described in Embodiment 5, instead of storing the difference value of the characteristic correction value between the elements adjacent in position, the difference value stores the difference value. If the excess capacity is exceeded, a value obtained by adding the excess value to the difference value may be stored as a difference value in the next adjacent element. By adding the excess value to the difference value of the next element, data can be restored with a minimum error.
また、 上記差分値を記憶する際に、 実施の形態 6で述べたように、 位置的に隣 接する素子どうしの特性補正値の差分値を記憶するのではなく、 入力値毎の素子 特性補正値の平均値と、 素子毎の特性補正値と平均値との差分値を記憶するよう にしてもよい。 このようにすることにより、 各素子の差分値が独立して記憶され ているため差分値が記憶容量を超過する場合、 その誤差が他の素子のガンマ補正 に影響を及ぼさないようにすることができる。  Also, when storing the difference value, as described in Embodiment 6, instead of storing the difference value of the characteristic correction value between the elements adjacent in position, the element characteristic correction value for each input value is stored. And the difference between the characteristic correction value and the average value of each element may be stored. In this way, when the difference value exceeds the storage capacity because the difference value of each element is stored independently, it is possible to prevent the error from affecting the gamma correction of other elements. it can.
また、 差分値を記憶する際に、 実施の形態 7で述べたように、 位置的に隣接す る素子どうしの特性補正値の差分値をデータ長と差分値で記憶するようにしても よい。 このようにすることにより、 柔軟に差分値を記憶させることができるとと もに、 差分値のデータ長を一緒に記憶させることで、 正確に素子特性補正値を復 元することができる。  When the difference value is stored, as described in the seventh embodiment, the difference value of the characteristic correction value between the elements adjacent in position may be stored as the data length and the difference value. By doing so, the difference value can be stored flexibly, and the element characteristic correction value can be accurately restored by storing the data length of the difference value together.
また、 素子特性補正値テーブルは、 上記実施の形態 2でも述べたように、 0か ら 2 5 5までの連続した入力データに対する特性捕正値を記憶するのではなく、 何点かの離散的な入力データに対する特性補正値を記憶するようにしてもよい。 また、 離散的な入力値に対する素子特性値を記憶させる場合、 実施の形態 2で も述べたように、 低階調部、 すなわち暗い領域のデータをよ.り多く記憶させるこ とで精度を向上させることができる。 また、 基準となる素子について 1番目の素子を基準素子としたが、 もちろんど の素子を基準素子としてもよレ、。 さらに、基準素子を 1つだけとするのではなく、 何点も基準素子をもっていてもよい。 産業上の利用の可能性 Also, as described in the second embodiment, the element characteristic correction value table does not store characteristic correction values for continuous input data from 0 to 255, but rather stores discrete characteristic values. Characteristic correction values for various input data may be stored. In addition, when element characteristic values corresponding to discrete input values are stored, as described in Embodiment 2, accuracy is improved by storing more data in a low gradation area, that is, in a dark area. Can be done. In addition, the first element is used as a reference element as a reference element. However, any element may be used as a reference element. Furthermore, instead of having only one reference element, any number of reference elements may be provided. Industrial applicability
この発明は、 ガンマ補正装置において、 各撮像素子ごとのガンマ捕正値を記憶 するガンマ補正値記憶手段を備え、 各素子毎にガンマ補正値を選択したガンマ補 正処理を行うことにより、 高精度なガンマ補正を行い、 画質劣化の少ない画像を 提供することができる。  According to the present invention, a gamma correction device includes a gamma correction value storage unit that stores a gamma correction value for each image sensor, and performs a gamma correction process in which a gamma correction value is selected for each element, thereby achieving high accuracy. Gamma correction to provide an image with little image quality degradation.

Claims

請求 の範囲 The scope of the claims
1 . 複数の撮像素子のガンマ特性を補正するガンマ捕正装置において、 すべての撮像素子のガンマ補正値を記憶するガンマ補正値記憶手段と、 上記ガンマ補正値記憶手段から素子毎のガンマ補正値を選択するガンマ補正値 選択手段と、 1. In a gamma correction device that corrects gamma characteristics of a plurality of imaging devices, a gamma correction value storage unit that stores gamma correction values of all imaging devices, and a gamma correction value for each device from the gamma correction value storage unit. Gamma correction value selection means to be selected;
上記ガンマ捕正値選択手段によつて選択されたガンマ補正値を用いて素子毎に 個別のガンマ補正を行うガンマ補正手段とを備えたことを特徴とするガンマ補正 Gamma correction means for performing individual gamma correction for each element using the gamma correction value selected by the gamma correction value selection means.
2 . 請求の範囲第 1項記載のガンマ補正装置において、 2. In the gamma correction device according to claim 1,
上記ガンマ補正値記憶手段は、 所定の画像を読み取つた離散的な入力値に対す るガンマ補正値を記億しており、  The gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image.
上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ捕正値 とから捕間処理を行い、 素子毎のガンマ補正値を算出するガンマ捕正値捕間手段 を備えたことを特徴とするガンマ補正装置。  Gamma correction value capturing means for performing capture processing from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means and calculating a gamma correction value for each element. A gamma correction device.
3 . 請求の範囲第 1項記載のガンマ捕正装置において、  3. The gamma correction device according to claim 1,
上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ補正値を記億する際に、 低階調部のガンマ補正値をより多く記憶するこ とを特徴とするガンマ補正装置。  The gamma correction value storage means stores more gamma correction values in a low gradation part when storing gamma correction values for discrete input values obtained by reading a predetermined image. Gamma correction device.
4. 複数の撮像素子のガンマ特性を補正するガンマ捕正装置において、 基準素子のガンマ捕正直と、 それぞれ位置的に隣接する素子どうしのガンマ補 正値の差分値とを、 予め定めた記憶容量で記憶するガンマ捕正値記憶手段と、 基準素子は記憶してあるガンマ補正値を用い、 それ以外の素子では、 上記基準 素子のガンマ補正値に当該素子の位置までに存在する素子の差分値をそれぞれ積 算することで、 素子毎のガンマ捕正値を算出するガンマ補正値算出手段と、 上記算出したガンマ捕正値から素子毎にガンマ捕正を行うガンマ補正手段とを 備えたことを特徴とするガンマ捕正装置。 4. In a gamma correction device that corrects the gamma characteristics of a plurality of imaging devices, a gamma correction straight line of a reference device and a difference value of a gamma correction value of each positionally adjacent device are stored in a predetermined storage capacity. The gamma correction value storage means for storing the gamma correction value stored in the reference element and the stored gamma correction value for the reference element. The gamma correction value calculating means for calculating the gamma correction value for each element by multiplying each of the elements, and the gamma correction means for performing gamma correction for each element from the calculated gamma correction value are provided. Characteristic gamma correction device.
5 . 請求の範囲第 4項記載のガンマ補正装置において、  5. The gamma correction device according to claim 4, wherein
上記ガンマ捕正値記憶手段は、 所定の画像を読み取つた離散的な入力値に対す るガンマ捕正値を記憶しており、 The gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. Gamma correction value
上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値 とから捕間処理を行い、 素子毎のガンマ捕正値を算出するガンマ補正値補間手段 を備えたことを特徴とするガンマ補正装置。  Gamma correction value interpolating means for performing interpolating processing based on the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means and calculating a gamma correction value for each element. Gamma correction device.
6 . 請求の範囲第 4項記載のガンマ補正装置において、 6. The gamma correction device according to claim 4, wherein
上記ガンマ捕正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ捕正値を記憶する際に、 低階調部のガンマ捕正値をより多く記憶するこ とを特徴とするガンマ補正装置。  The gamma correction value storage means, when storing a gamma correction value corresponding to a discrete input value obtained by reading a predetermined image, stores more gamma correction values in a low gradation part. Characteristic gamma correction device.
7 . 複数の撮像素子のガンマ特性を補正するガンマ捕正装置において、 基準素子のガンマ補正値と、 それぞれ位置的に隣接する素子どうしのガンマ捕 正値の差分値とを、 予め定めた記憶容量で記憶し、 上記差分値が予め定めた記憶 容量を超過した場合、 隣接する素子では該差分値に上記予め定めた記憶容量を超 過した値を加算して記憶するガンマ補正値記憶手段と、  7. In a gamma correction device that corrects the gamma characteristics of a plurality of imaging devices, a gamma correction value of a reference device and a difference value of a gamma correction value of a device adjacent to each other are stored in a predetermined storage capacity. When the difference value exceeds a predetermined storage capacity, a gamma correction value storage means for adding and storing a value exceeding the predetermined storage capacity to the difference value in an adjacent element,
基準素子は記憶してあるガンマ捕正値を用レ、、 それ以外の素子では、 上記基準 素子のガンマ補正値に当該素子の位置までに存在する素子の差分値をそれぞれ積 算することで、 素子毎のガンマ補正値を算出するガンマ補正値算出手段と、 上記算出したガンマ補正値から素子毎にガンマ補正を行うガンマ補正手段とを 備えたことを特徴とするガンマ補正装置。  For the reference element, the stored gamma correction value is used.For the other elements, the difference value of the element existing up to the position of the element is multiplied by the gamma correction value of the reference element. A gamma correction device comprising: a gamma correction value calculation unit that calculates a gamma correction value for each element; and a gamma correction unit that performs gamma correction for each element from the calculated gamma correction value.
8 . 請求の範囲第 7項記載のガンマ補正装置において、  8. The gamma correction device according to claim 7,
上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ補正値を記憶しており、  The gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image,
上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値 とから補間処理を行い、 素子毎のガンマ補正値を算出するガンマ補正値補間手段 を備えたことを特徴とするガンマ補正装置。  Gamma correction value interpolation means for performing an interpolation process from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means and calculating a gamma correction value for each element. Gamma correction device.
9 . 請求の範囲第 7項記載のガンマ補正装置において、 9. The gamma correction device according to claim 7, wherein
上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ補正値を記憶する際に、 低階調部のガンマ補正値をより多く記憶するこ とを特徴とするガンマ補正装置。  The gamma correction value storage means stores more gamma correction values in a low gradation part when storing gamma correction values for discrete input values obtained by reading a predetermined image. Gamma correction device.
1 0 . 複数の撮像素子のガンマ特性を補正するガンマ補正装置において、 入力値毎の各素子のガンマ捕正値の平均値と、 該平均値と上記各素子毎のガン マ捕正値との差分値を記憶したガンマ補正値記憶手段と、 10. In a gamma correction device that corrects the gamma characteristics of a plurality of image sensors, Gamma correction value storage means for storing an average value of gamma correction values of each element for each input value, and a difference value between the average value and the gamma correction value for each element,
素子毎のガンマ補正値を、 上記ガンマ補正値の平均値に、 素子毎の差分値を加 算して算出するガンマ補正値算出手段と、  Gamma correction value calculating means for calculating a gamma correction value for each element by adding a difference value for each element to an average value of the gamma correction values;
上記算出したガンマ補正値から素子毎にガンマ補正を行うガンマ補正手段とを 備えたことを特徴とするガンマ補正装置。  A gamma correction device comprising: gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
1 1 . 請求の範囲第 1 0項記載のガンマ補正装置において、  11. The gamma correction device according to claim 10, wherein:
上記ガンマ捕正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ捕正値を記憶しており、  The gamma correction value storage means stores a gamma correction value corresponding to a discrete input value obtained by reading a predetermined image,
上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ捕正値 とから補間処理を行い、 素子毎のガンマ補正値を算出するガンマ捕正値補間手段 を備えたことを特徴とするガンマ補正装置。  Gamma correction value interpolation means for performing an interpolation process from the input value of the predetermined image and the gamma correction value stored in the gamma correction value storage means and calculating a gamma correction value for each element. Gamma correction device.
1 2 . 請求の範囲第 1 0項記載のガンマ補正装置において、  12. The gamma correction device according to claim 10, wherein
上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ補正値を記憶する際に、 低階調部のガンマ捕正値をより多く記憶するこ とを特徴とするガンマ補正装置。  The gamma correction value storage means is characterized in that when storing a gamma correction value for a discrete input value obtained by reading a predetermined image, the gamma correction value in a low gradation part is stored in a larger amount. Gamma correction device.
1 3 . 複数の撮像素子のガンマ特性を捕正するガンマ捕正装置において、 基準素子のガンマ捕正値と、 それぞれ位置的に隣接する素子どうしのガンマ捕 正値との差分値と、 該差分値のデータ長を記憶するガンマ補正値記憶手段と、 基準素子は記憶してあるガンマ捕正値によりガンマ捕正を行い、 それ以外の素 子では上記基準素子のガンマ補正値に当該素子の位置まで存在する素子の差分値 をそれぞれ積算することで、 素子毎のガンマ補正値を算出するガンマ補正値算出 手段と、  13. A gamma correction device that corrects gamma characteristics of a plurality of image pickup devices, wherein: a difference value between a gamma correction value of a reference device and a gamma correction value of a device adjacent to each other in position; Gamma correction value storage means for storing the data length of the value, the reference element performs gamma correction using the stored gamma correction value, and the other elements store the gamma correction value of the reference element in the gamma correction value of the reference element. Gamma correction value calculating means for calculating a gamma correction value for each element by integrating the difference values of the elements existing up to
上記算出したガンマ補正値から素子毎にガンマ補正を行うガンマ補正手段とを 備えたことを特徴とするガンマ補正装置。  A gamma correction device comprising: gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
1 4 . 請求の範囲第 1 3項記載のガンマ補正装置において、  14. The gamma correction device according to claim 13, wherein:
上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ補正値を記憶しており、  The gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image,
上記ガンマ補正値記憶手段に記憶してある所定の画像の入力値とガンマ補正値 とから補間処理を行い、 素子毎のガンマ補正値を算出するガンマ補正値補間手段 を備えたことを特徴とするガンマ捕正装置。 The input value and gamma correction value of a predetermined image stored in the gamma correction value storage means And a gamma correction value interpolating means for calculating a gamma correction value for each element.
1 5 . 請求の範囲第 1 3項記載のガンマ補正装置において、  15. The gamma correction device according to claim 13, wherein:
上記ガンマ補正値記憶手段は、 所定の画像を読み取った離散的な入力値に対す るガンマ捕正値を記憶する際に、 低階調部のガンマ捕正値をより多く記憶するこ とを特徴とするガンマ補正装置。  The gamma correction value storage means, when storing a gamma correction value corresponding to a discrete input value obtained by reading a predetermined image, stores more gamma correction values in a low gradation part. Gamma correction device.
1 6 . 複数の撮像素子のガンマ特性を捕正するガンマ補正装置において、 複数のガンマ補正テーブルを記憶するガンマ補正テーブル記憶手段と、 素子毎にガンマ補正テーブルを選択するための選択情報を記憶するガンマ捕正 テーブル選択情報記憶手段と、  16. In a gamma correction device for correcting gamma characteristics of a plurality of imaging devices, a gamma correction table storage means for storing a plurality of gamma correction tables, and selection information for selecting a gamma correction table for each device. Gamma correction table selection information storage means,
上記ガンマ補正テーブル記憶手段と上記ガンマ捕正テーブル選択情報記憶手段 とから素子毎に対応したガンマ捕正テーブルを選択するガンマ捕正テーブル選択 手段と、  Gamma correction table selection means for selecting a gamma correction table corresponding to each element from the gamma correction table storage means and the gamma correction table selection information storage means;
選択したガンマ補正テーブルによりガンマ補正を行うガンマ捕正手段とを備え たことを特徴とするガンマ捕正装置。  A gamma correction device comprising: gamma correction means for performing gamma correction according to a selected gamma correction table.
1 7 . 請求の範囲第 1 6項記載のガンマ補正装置において、  17. The gamma correction device according to claim 16, wherein:
上記ガンマ補正テーブル記憶手段は、 ガンマ補正量が最も小さいガンマ補正テ 一ブル、 あるいはガンマ補正量が最も大きいガンマ捕正テーブルを基準のガンマ 補正テーブルとして記憶し、 その他のガンマ捕正テーブルは、 基準のガンマ捕正 テーブルがガンマ捕正量の最も小さいガンマ補正テーブルを用いる場合は、 ガン マ補正量が小さい順番にガンマ補正テーブルを並べた場合に順番が隣り合うガン マ補正値の差分値を記憶し、 一方、 基準のガンマ補正テーブルとしてガンマ補正 量の最も大きいガンマ補正テーブルを用いる場合は、 ガンマ補正量が大きい順番 にガンマ補正テーブルを並べた場合に順番が隣り合うガンマ補正値の差分値を記 憶し、  The gamma correction table storage means stores a gamma correction table having the smallest amount of gamma correction or a gamma correction table having the largest amount of gamma correction as a reference gamma correction table. When using the gamma correction table with the smallest gamma correction amount for the gamma correction table, if the gamma correction tables are arranged in the order of the smallest gamma correction amount, the difference value between the gamma correction values that are next to each other is stored. On the other hand, when the gamma correction table having the largest amount of gamma correction is used as the reference gamma correction table, when the gamma correction tables are arranged in the descending order of the amount of gamma correction, the difference value between the gamma correction values that are adjacent to each other is calculated. Remember,
上記基準のガンマ捕正テーブルと差分値とからガンマ補正テーブルを算出する ガンマ補正テーブル算出手段を備えたことを特徴とするガンマ捕正装置。  A gamma correction device comprising: a gamma correction table calculation unit that calculates a gamma correction table from the reference gamma correction table and a difference value.
1 8 . 請求の範囲第 1 6項記載のガンマ補正装置において、  18. The gamma correction device according to claim 16, wherein:
上記ガンマ補正テーブル選択手段は、 素子のガンマ補正テープノレと、 ガンマ捕 正テーブル記憶手段に記憶してある複数のガンマ補正テ ブルとで、 ガンマ捕正 値の最小二乗和が最も小さくなるガンマ捕正テーブルを選択することを特徴とす るガンマ補正装置。 The gamma correction table selection means includes a gamma correction tape for the element and a gamma capture. A gamma correction device characterized by selecting a gamma correction table that minimizes the least square sum of gamma correction values among a plurality of gamma correction tables stored in a positive table storage means.
1 9 . 複数の撮像素子のガンマ特性を補正するガンマ補正装置において、 ガンマ補正前の基準素子の入力値に対する出力特性補正値である素子特性捕正 値と、 それぞれ位置的に隣接する素子どうしにおける、 ガンマ補正前の入力値に 対する出力特性補正値である素子特性捕正値の差分値とを、 予め定めた記憶容量 で記憶する素子特性捕正値記憶手段と、  1 9. In a gamma correction device that corrects the gamma characteristics of a plurality of image sensors, a device characteristic correction value, which is an output characteristic correction value for an input value of a reference device before gamma correction, and a device characteristic correction value between devices that are adjacent in position. Element characteristic correction value storage means for storing, with a predetermined storage capacity, a difference value of an element characteristic correction value which is an output characteristic correction value with respect to an input value before gamma correction,
基準素子は記憶してある素子特性補正値によりガンマ捕正値を算出し、 それ以 外の素子では、 上記基準素子の素子特性補正値に当該素子の位置までに存在する 素子の差分値をそれぞれ積算することで、 素子毎のガンマ補正値を算出する素子 特性捕正値算出手段と、  For the reference element, the gamma correction value is calculated from the stored element characteristic correction value. For the other elements, the difference value of the element existing up to the position of the element is added to the element characteristic correction value of the reference element. An element characteristic correction value calculating means for calculating a gamma correction value for each element by integrating,
上記算出した素子毎の特性補正値から素子毎にガンマ捕芷値を算出するガンマ 補正値算出手段と、  Gamma correction value calculation means for calculating a gamma capture value for each element from the calculated characteristic correction value for each element,
上記算出したガンマ捕正値から素子毎にガンマ補正を行うガンマ捕正手段とを 備えたことを特徴とするガンマ捕正装置。  A gamma correction device comprising: gamma correction means for performing gamma correction for each element from the calculated gamma correction value.
2 0 . 請求の範囲第 1 9項記載のガンマ補正装置において、  20. In the gamma correction apparatus according to claim 19,
上記素子特性記憶手段は、 位置的に隣接する素子どうしの素子特性補正値の差 分値を予め定めた記憶容量で記憶し、 差分値が予め定めた記憶容量を超過した場 合、 隣接する素子では差分値に超過した値を加算して記憶することを特徴とする ガンマ捕正装置。  The element characteristic storage means stores a difference value of an element characteristic correction value between positionally adjacent elements with a predetermined storage capacity, and, when the difference value exceeds a predetermined storage capacity, an adjacent element. The gamma correction device is characterized in that a value exceeding the difference value is added and stored.
2 1 . 請求の範囲第 1 9項記載のガンマ補正装置において、  21. In the gamma correction apparatus according to claim 19,
上記素子特性補正値記 I 手段は、 素子の素子特' t1生補正値の平均値と、 その平均 値と各素子毎の素子特性捕正値の差分値とを記憶し、 The element characteristic correction value Symbol I means stores an average value of the elements JP 't 1 raw correction value of the element, and the average value and the difference value of the element characteristics ToTadashichi for each element,
上記素子特性補正値算出手段は、 各素子毎の素子特性捕正値の平均値に、 素子 毎の差分値を加算した値から素子特性補正値を算出することを特徴とするガンマ  The element characteristic correction value calculating means calculates an element characteristic correction value from a value obtained by adding a difference value for each element to an average value of element characteristic correction values for each element.
2 2 . 請求の範囲第 1 9項記載のガンマ補正装置において、 22. In the gamma correction apparatus according to claim 19,
上記素子特性記憶手段は、 位置的に隣接する素子どうしの素子特性補正値の差 分値をそのデータ長と共に記憶することを特徴とするガンマ補正装置。 The element characteristic storage means stores a difference in element characteristic correction value between elements adjacent in position. A gamma correction device for storing a minute value together with its data length.
2 3 . 請求の範囲第 1 9項記載のガンマ補正装置において、 23. In the gamma correction device according to claim 19,
上記素子特性捕正値記憶手段は、 所定の画像を読み取った離散的な入力値に対 する素子特性補正値を記憶し、  The element characteristic correction value storage means stores an element characteristic correction value corresponding to a discrete input value obtained by reading a predetermined image,
上記素子特性捕正値補間手段は、 上記素子特性捕正値記憶手段に記憶してある 所定の画像の入力値と素子特性補正値とから補間処理を行って素子毎の素子特性 補正値を算出することを特徴とするガンマ補正装置。  The element characteristic correction value interpolation means calculates an element characteristic correction value for each element by performing an interpolation process from the input value of the predetermined image and the element characteristic correction value stored in the element characteristic correction value storage means. A gamma correction device.
2 4. 請求の範囲第 1 9項記載のガンマ補正装置において、 2 4. In the gamma correction device according to claim 19,
上記素子特性補正値記憶手段は、 所定の画像を読み取つた離散的な入力値に対 する素子特性補正値を記憶させる際に、 低階調部の素子特性補正値をより多く記 憶させることを特徴とするガンマ補正装置。  The element characteristic correction value storage means stores more element characteristic correction values in the low gradation part when storing element characteristic correction values for discrete input values obtained by reading a predetermined image. Characteristic gamma correction device.
PCT/JP2001/005562 2000-06-29 2001-06-28 Gamma correction device WO2002001850A1 (en)

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