JP2002016805A - Gamma correction device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gamma correction device by which the memory capacity of the gamma correction value can be made small regardless of the size of input data. SOLUTION: A gamma correction value with respect to discreting input data is stored in a gamma correction value storing circuit 105. An appropriate gamma correction value is calculated by interpolation in a gamma correction value interpolating circuit 404, by using a pattern value containing corresponding input data from a pattern value storing circuit 408 which stores the degree of discreteness of the input data, and the gamma correction value stored in the gamma correction value storing circuit 105. Consequently, gamma correction is performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gamma correction device, and more particularly to a gamma correction when an image scanner is used as an imaging device.

[0002]

2. Description of the Related Art In a conventional image scanner, gamma correction is performed between a display device such as a monitor for displaying a captured image to maintain the linearity of an output signal with respect to an input signal. Generally, a monitor which is a display device has a characteristic of gamma = 2.2, so that the image scanner performs gamma correction so that gamma = 0.45.
Gamma correction is performed so that the characteristics of the output signal with respect to the input signal are linear.

The actual gamma correction is as shown in FIG.
By calculating a gamma correction value for the input signal in advance and storing the gamma correction table in the ROM, referring to the address of the ROM by the input signal, and outputting the gamma correction data stored at that address as an output signal. Can be realized.

Although the gamma characteristic differs for each element of the image scanner, most image scanners perform gamma correction with only one gamma correction value. The image quality has deteriorated due to the occurrence of streaks or streaks.

Conventionally, shading correction has been performed in order 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 characteristics also vary, so that the image quality is deteriorated.

Further, as a method of reducing the storage capacity of the gamma correction table required for performing the above gamma correction,
Although the purpose is not to reduce the capacity of the gamma correction table for each element, as a method of reducing the capacity of the correction table when a device has several types of gamma correction tables, for example, a digital gamma correction method disclosed in Japanese Patent Application Laid-Open No. 8-195895 is used. There are correction methods and devices.

Hereinafter, the conventional example will be described in detail. FIG. 28 is a block diagram showing a conventional device for performing gamma correction. In FIG. 28, reference numeral 2801 denotes an input terminal to which data is input, 2802 denotes an input selection unit for switching and outputting a signal from the input terminal 2801 and an output of a microprocessor described later, and 2803 denotes a signal output from the input selection unit 2802. Gamma characteristic correction unit for processing 2804
Is a characteristic selection unit, 2805 is a microprocessor that receives the output of the characteristic selection unit 2804, and 2806 is a data storage unit that supplies data to the microprocessor 2805. Reference numerals 2806 (1) to 2806 (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. According to the gamma characteristic selection signal supplied from the characteristic selection unit 2804, the microprocessor 2805 reads the reference data stored from the memory corresponding to the gamma characteristic selected from the data storage unit 2806, and a plurality of difference values. The microprocessor 2805 restores the gamma characteristic table using the read reference data and the plurality of difference values, and stores the gamma characteristic table in the gamma characteristic correction unit 2803 in the form of a lookup table. Then, the gamma 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 data storage unit 2806 does not store the gamma correction table as it is, but reduces the storage capacity by storing reference data and a plurality of difference values. For example, when the gamma characteristic is as shown in FIG. 29, the data storage unit 2806 stores the input data X
The gamma correction value G (1) corresponding to (1) is stored in the reference data, and the remaining gamma correction values are difference values DG having a relationship of DG (k) = G (k) -G (k-1). It is stored in the form of (k). That is, a 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.

However, the conventional gamma correction apparatus has a problem that the storage capacity does not decrease in a low gradation area, that is, in an area where the value of input data is small, because the amount of change in gamma characteristics is large. For example, when the gamma correction data of a certain element has the gamma correction characteristic as shown in FIG. 30A, the gamma correction value for the input data is as shown in FIG. Here, when the gamma correction value 5 corresponding to the input data 1 is used as the reference data, the difference value corresponding to the input data 2 is 22-5 = 17. Similarly, the difference value corresponding to the input data 3 is 12,
The difference value corresponding to the input data 4 is 6. Since the capacity for storing the difference value must be able to store the maximum value of the difference value, in this case, a storage capacity of 5 bits is required to store 17. As described above, in the area where the input data is small, the difference value is not reduced due to the gamma characteristic of the element, and the storage capacity of the gamma correction value cannot be reduced in some cases.

Further, the conventional gamma correction apparatus 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 can be performed by preparing a plurality of gamma correction tables, but different gamma corrections cannot be performed for each element.

[0013]

The conventional gamma correction apparatus is configured as described above. Since the same gamma correction table is prepared for each element and gamma correction is performed, image quality deterioration can be sufficiently prevented. It was not something. Further, in a region where the input data is small, the difference value does not become small due to the gamma characteristic of the element, so that the storage capacity of the gamma correction value cannot be reduced efficiently.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has as its object to provide a gamma correction device capable of performing gamma correction with high accuracy.
It is another object of the present invention to provide a gamma correction device capable of reducing the storage capacity of a gamma correction value regardless of the size of input data.

[0015]

A gamma correction device according to a first aspect of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices. The gamma correction device stores gamma correction values of all image pickup devices. 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 individual gamma for each element using the gamma correction value selected by the gamma correction value selection means. Gamma correction means for performing correction.

According to a second aspect of the present invention, there is provided the gamma correction apparatus according to the first aspect, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating unit that stores a correction value, performs an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage unit, and calculates a gamma correction value for each element. It is provided with.

According to a third aspect of the present invention, there is provided a gamma correction apparatus according to the first aspect, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. When the correction value is stored, the gamma correction value of the low gradation part is stored more.

A gamma correction device according to a fourth aspect of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, wherein a gamma correction value of a reference device and a gamma correction value of a gamma correction value of a positionally adjacent device. A gamma correction value storage means for storing a difference value of the correction value with a predetermined storage capacity; a gamma correction value for each element from the gamma correction value stored in the gamma correction value storage means; A gamma correction value calculating unit that calculates a value obtained by integrating the difference value up to the element position with the gamma correction value of the reference element using the correction value, and performs gamma correction for each element from the calculated gamma correction value. Gamma correction means.

According to a fifth aspect of the present invention, there is provided a gamma correction apparatus according to the fourth aspect, wherein the gamma correction value storage means stores the gamma for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating unit that stores a correction value, performs an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage unit, and calculates a gamma correction value for each element. It is provided with.

According to a sixth aspect of the present invention, there is provided a gamma correction apparatus according to the fourth aspect, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. When the correction value is stored, the gamma correction value of the low gradation part is stored more.

A gamma correction device according to a seventh aspect of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, wherein a gamma correction value of a reference device and a gamma correction value of a device adjacent in position are used. Gamma correction value storage means for storing the difference value of the correction value with 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 value for each element is used from the gamma correction value stored in the gamma correction value storage means, the stored gamma correction value is used for the reference element, and the gamma correction value of the reference element is used for other elements to the element position. And a gamma correction unit for performing gamma correction for each element from the calculated gamma correction value.

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 stores a gamma for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating unit that stores a correction value, performs an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage unit, and calculates a gamma correction value for each element. It is provided with.

According to a ninth aspect of the present invention, there is provided the gamma correction apparatus according to the seventh aspect, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. When the correction value is stored, the gamma correction value of the low gradation part is stored more.

A gamma correction apparatus according to a tenth aspect of the present invention is a gamma correction apparatus for correcting gamma characteristics of a plurality of image pickup devices, wherein an average value of the gamma correction values of the elements, Gamma correction value storage means for storing a difference value of the gamma correction values of the elements, and a gamma correction value for each element from the gamma correction values stored in the gamma correction value storage means, and a difference value for each element to an average value of the gamma correction values. And gamma correction means for performing gamma correction for each element from the calculated gamma correction value.

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 stores gamma for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating unit that stores a correction value, performs an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage unit, and calculates a gamma correction value for each element. It is provided with.

A gamma correction apparatus according to a twelfth aspect of the present invention is the gamma correction apparatus according to the tenth aspect, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. When the correction value is stored, the gamma correction value of the low gradation part is stored more.

A gamma correction apparatus according to a thirteenth aspect of the present invention is a gamma correction apparatus for correcting gamma characteristics of a plurality of image pickup devices, wherein a gamma correction value of a reference device and a gamma correction value of a positionally adjacent device. A gamma correction value storing means for storing a difference value of the correction value and its data length; a gamma correction value for each element from the gamma correction value stored in the gamma correction value storing means; A gamma correction value calculating means for calculating a gamma correction value by integrating a difference value up to an element position with a gamma correction value of a reference element for other elements, and gamma correction for each element from the calculated gamma correction value. And gamma correction means for performing the following.

The gamma correction device according to a fourteenth aspect of the present invention is the gamma correction device according to the thirteenth aspect, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating unit that stores a correction value, performs an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage unit, and calculates a gamma correction value for each element. It is provided with.

The gamma correction device according to a fifteenth aspect of the present invention is the gamma correction device according to the thirteenth aspect, wherein the gamma correction value storage means stores the gamma for a discrete input value obtained by reading a predetermined image. When the correction value is stored, the gamma correction value of the low gradation part is stored more.

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 image pickup devices, wherein a gamma correction table storage means for storing a plurality of gamma correction tables, Gamma correction table selection information storage means for storing selection information for selecting a gamma correction table, and a gamma correction table corresponding to each element is selected from the gamma correction table storage means and the gamma correction table selection information storage means. Gamma correction table selecting means for performing gamma correction based on the selected gamma correction table.

According to a seventeenth aspect of the present invention, in the gamma correction apparatus according to the sixteenth aspect, the gamma correction table storage means includes a gamma correction table or a gamma correction table having the smallest gamma correction amount. The gamma correction table with the largest amount is stored as the reference gamma correction table, and the other gamma correction tables are arranged in the order of the smallest gamma correction amount when the reference gamma correction table uses the gamma correction table with the smallest gamma correction amount. When the gamma correction tables are arranged, the difference value between the gamma correction values adjacent to each other is stored. On the other hand, when the gamma correction table having the largest gamma correction amount is used as the reference gamma correction table, the gamma correction amount is large. Gamma correction that is adjacent in order when gamma correction tables are arranged in order Storing the difference value, it is obtained with a gamma correction table calculating means for calculating the gamma correction table and a gamma correction table and the difference value of the reference.

The gamma correction apparatus according to claim 18 of the present invention is the gamma correction apparatus according to claim 16, wherein the gamma correction table selecting means includes a gamma correction table for the element and a gamma correction table storage means. The gamma correction table that minimizes the least square sum of the gamma correction values among the plurality of stored gamma correction tables is selected.

A gamma correction device according to a nineteenth aspect of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, wherein the gamma correction device corrects the gamma characteristics of a plurality of image pickup devices,
An element characteristic correction value storage unit that stores a characteristic correction value before gamma correction with a predetermined storage capacity and a difference value between element characteristic correction values of elements adjacent in position are stored in the element characteristic correction value storage unit. The element characteristic correction value for each element is calculated from the element characteristic correction value, and the gamma correction value is calculated for the reference element based on the stored element characteristic correction value for the reference element. An element characteristic correction value calculation unit that calculates the difference value from the integrated value, a gamma correction value calculation unit that calculates a gamma correction value for each element from the calculated characteristic correction value for each element, and a gamma correction value calculated from the calculated gamma correction value. Gamma correction means for performing gamma correction for each element.

In the gamma correction apparatus according to a twentieth aspect of the present invention, in the gamma correction apparatus according to the nineteenth aspect, the element characteristic storage means stores a difference between element characteristic correction values of elements adjacent in position. The 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.

In the gamma correction apparatus according to a twenty-first aspect of the present invention, in the gamma correction apparatus according to the nineteenth aspect, the element characteristic correction value storage means stores the average value of the element characteristic correction values of the elements, The difference value between the average value and the element characteristic correction value for each element is stored, and the element characteristic correction value calculation means calculates the element value from the value obtained by adding the difference value for each element to the average value of the element characteristic correction value for each element. This is for calculating a characteristic correction value.

In the gamma correction apparatus according to a twenty-second aspect of the present invention, in the gamma correction apparatus according to the nineteenth aspect, the element characteristic storage means stores a difference between element characteristic correction values of elements adjacent in position. The value is stored together with the data length.

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 stores a discrete input value obtained by reading a predetermined image. The element characteristic correction value is stored, and the element characteristic correction value interpolating means performs an interpolation process from the input value of the predetermined image and the element characteristic correction value stored in the element characteristic correction value storing means, and performs an interpolation process for each element. An element characteristic correction value is calculated.

In the gamma correction apparatus according to a twenty-fourth aspect of the present invention, in the gamma correction apparatus according to the nineteenth aspect, the element characteristic correction value storing means stores a discrete input value obtained by reading a predetermined image. When the element characteristic correction value is stored, the element characteristic correction value of the low gradation part is stored more.

[0039]

Embodiment 1 Hereinafter, a gamma correction device according to Embodiment 1 of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing a configuration of the gamma correction device according to the first embodiment. In FIG. 1, reference numeral 101 denotes an image sensor such as a CCD, and 102 denotes a CCD 10
A / D converter for converting the output of 1 into digital, 10
Reference numeral 3 denotes a gamma correction circuit that receives the output of the A / D converter 102; 104, a gamma correction table selection circuit that selects and extracts a required gamma correction value from a gamma correction value storage circuit 105; and 106, an element selection circuit.

The operation will be described below. Image sensor 1
At 01, an input image is fetched, the input signal is digitized by the A / D converter 102, and then gamma correction is performed by the gamma correction circuit 103 using an individual gamma correction value for each element. Here, the gamma correction value for each element is selected from the gamma correction table stored in the gamma correction value storage circuit 105, the gamma correction table for the corresponding element is selected by the gamma correction table selection circuit 104, and the selected gamma correction value is selected. Gamma correction circuit 103 based on the gamma correction value in the table
Perform gamma correction in.

The image scanner reads an image by a configuration as shown in FIG. That is, in FIG. 2, reference numeral 201 denotes a document to be read, 202 denotes illumination, and 203 denotes a lens arranged between the document to be read 201 and the image sensor 204. The reading principle is as follows.
1 is illuminated by illumination 202 and the reflected light is
An image is formed at 3 and a 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 a first element to an Nth element, and converts a light signal into an electric signal for each element.

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.

For example, when the gamma correction value corresponding to the input value of each element has a characteristic as shown in FIG. 3A, the gamma correction value storage circuit 105 stores the value shown in FIG. Will be. In this case, the gamma correction value is 8 bits,
That is, it is represented by one byte. First, the gamma correction value storage circuit 105 stores 256 gamma correction values in one byte for the input values 0 to 255 of the first element, and then stores the gamma correction values of the second element in one byte in the same manner.
56 are stored. In this way, all gamma correction values up to the Nth element of the image sensor are stored.

To calculate the gamma correction value of the N-th element, the gamma correction table selecting circuit 104 calculates the gamma correction value 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 No. element. For this, the gamma correction value of the Nth element on the gamma correction value storage circuit 105 is represented by (start address) = 1 * 256 * (N−1). ) Since it can be calculated in bytes, the data of 256 bytes from this start address becomes 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.

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 a correction table corresponding to each pixel is prepared using the gamma correction table selecting means 104. Since gamma correction is selectively performed, gamma correction with high accuracy can be performed, and deterioration in image quality can be suppressed.

(Embodiment 2) Next, a gamma correction apparatus according to Embodiment 2 of the present invention will be described. In the present embodiment, in the configuration shown in the first embodiment,
0 to 255 to reduce the gamma correction table
Instead of storing the gamma correction values for continuous input data up to, 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. 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.

Generally, in order to calculate the gamma correction value, the gamma correction value shown in FIG.
The gamma correction value is calculated from the gray chart value and the read value by reading the gray chart of which the value is known in advance from the scanner as shown in. The gamma correction value is calculated by interpolating the values by interpolation.

Therefore, the gamma correction value storage circuit 105
If the gamma correction value for the gray chart pattern is stored in advance and the gamma correction value is interpolated by interpolation processing, the storage capacity can be reduced. For example, as shown in FIG. 5, in the case of a gray chart having 10 patterns, the storage capacity can be reduced to 10/256 as compared with the case of 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 a value obtained by measuring a 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.

In the gamma correction value interpolation circuit 404,
The gamma correction value is interpolated 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. For example, when the gamma correction value of the first element in FIG. 6 is interpolated, the interpolation processing can be performed by linearly interpolating between the data as shown in FIG. For example, the gamma correction value Y for the value X from the pattern values 25 to 50 can be calculated as follows: A = (123−90) / (50−25) Y = A * (X−25) +90 Based on the gamma correction value interpolated by the gamma correction value interpolation circuit 404 in this manner,
The gamma correction circuit 103 can perform gamma correction for each element.

When a gamma correction value for a discrete input value is stored, a larger number of gamma correction values for a pattern in a low gradation portion, that is, a pattern in a dark area may be stored. This is because the gamma correction curve has a large change in the low gradation portion, and therefore, the gamma correction accuracy can be improved by taking more data in this region.

For example, as shown in FIG. 8, when the ideal gamma curve whose gamma correction curve has a value of gamma 2.2 is linearly approximated by ten discrete data, the gradation is uniformly set to X.
It can be seen that, in the case of approximating by dividing by (0) to X (9), the error between the gamma interpolated in the low gradation region and the ideal gamma curve increases. This is because the gamma correction curve greatly changes in a low gradation portion. Therefore, as shown in FIG. 9, it can be seen that the error from the ideal gamma curve can be minimized by increasing the number of data in the low gradation area even for the same 10 data.

Also in the structure shown in FIG. 4, the gray chart used for calculating the gamma correction value is changed to a pattern having more low gradation parts, that is, a chart having more patterns close to black, or a gray chart. By selecting more low-gradation portions as patterns to be used for gamma correction in the chart, it is possible to store more gamma correction values in the low-gradation portions in the gamma correction value storage circuit 105.

As described above, according to the second embodiment, the gamma correction value for discrete input data is stored in the gamma correction value storage circuit 105, and the pattern value storage circuit 408 storing the degree of discreteness of the input data. The pattern value including the corresponding input data and the gamma correction value storage circuit 10
The gamma correction is performed by calculating an appropriate gamma correction value by interpolation processing in the gamma correction value interpolation circuit 404 using the gamma correction value stored in No. 5 and performing gamma correction for each pixel. As a result, it is possible to suppress the deterioration of the image quality, to reduce the storage capacity required for storing the gamma correction value, and to reduce the cost. 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.

Although the first element is used as a reference element as a reference element, any element may be used as a reference element. Further, instead of using only one reference element, any number of reference elements may be provided. Further, the case where the gamma correction value for the discrete input value is stored and the case where 10 patterns of the gray chart are stored has been described, but the number of patterns is not limited to this. Furthermore, when interpolating gamma correction values, interpolation may be performed not by linear approximation but by a curve such as a quadratic curve.

(Embodiment 3) Hereinafter, a gamma correction apparatus according to Embodiment 3 of the present invention will be described with reference to the drawings. FIG. 10 is a block diagram illustrating a configuration of the gamma correction device according to the third embodiment. 10, the same reference numerals as those in FIG. 1 denote the same or corresponding parts, and a gamma correction value calculation circuit 1004 is provided instead of the gamma correction table selection circuit 104 in FIG. 1, and instead of the gamma correction value storage circuit 105, A gamma correction table for the reference element,
A gamma correction value storage circuit 1005 that stores a gamma correction table of each of the other elements as a difference value with respect to the reference element.
Is provided.

The operation will be described below. Image sensor 1
At 01, an input image is fetched, the input signal is digitized by the A / D converter 102, and then gamma correction is performed by the gamma correction circuit 103 using an individual gamma correction value for each element. The gamma correction value is stored in the gamma correction value storage unit 1005
From the gamma correction value stored in the
The gamma correction value calculation circuit 1004 calculates the gamma correction value of the element selected in.

In the gamma correction device according to the third embodiment, 1
Instead of storing the entire gamma correction table for each element from the #th element to the Nth element as it is, storing the difference value between the gamma correction table of the reference element and the gamma correction table of the positionally adjacent element Thus, the storage capacity is reduced.

Generally, gamma correction is performed by using gamma correction values for input data stored in a ROM in a table format, as shown in FIG. As described above, the when the gamma correction table to try to have every element in the 640 element content, for example, 8-bit R, G, B3 ^{colors, 2 8 × 3 × 640 =} 491,520 bytes capacity needs of Becomes Therefore, 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 value of the gamma correction table between the positionally adjacent elements is stored to reduce the capacity. Make it smaller. Hereinafter, a method of calculating the difference value will be described in detail with reference to FIG.

In FIG. 11, a table 1101 shows gamma correction values for each element, and stores gamma correction values for input values of the first to fourth elements.
In this case, the first element is a reference element, and the first element stores the gamma correction value in 8 bits as it is. For the second and subsequent elements, as shown in a table 1102, a difference value of the gamma correction value between elements adjacent in position is stored for each input value. That is, in the case of the second element, the difference value is stored as a difference value for each input value with the first element, and in the case of the third element, a difference value is stored for each input value with the second element.

For example, the difference value of the input value 1 of the second element is
2nd element gamma correction value 18 and 1st element gamma correction value 21
And the difference value is -3 (18-21). When the difference value is calculated in this way, a value as shown in a table 1102 in FIG. 11 is obtained.

Looking at the difference value in the table 1102,
Since this is a difference between adjacent pixels, the difference value becomes significantly smaller than the original gamma correction value due to a small difference in element characteristics. In the example of FIG. 11, the value is from -3 to 2. Since storing these numerical values requires only three bits, the storage capacity can be reduced to about 3/8.
The thus calculated reference element gamma correction value and difference value are stored in the gamma correction value storage circuit 1005. In this case, the difference value is sequentially stored in three bits.

As described above, when the first element is used as the reference element, the gamma correction table of the first element is stored in the gamma correction table of the gamma correction value storage circuit 1005, and the second element is stored in the difference value Δ1. The difference value of the first element, the difference value Δ2
, Gamma correction values such as a difference value between the third element and the second element are sequentially stored.

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 a 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. 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 correction is performed using the stored gamma correction value. 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.

For the second and subsequent elements, a gamma correction value is 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, thereby performing gamma correction. For example,
When calculating the gamma correction value corresponding to the input value 0 of the fourth element, the gamma correction value corresponding to the input value 0 of the first element as the reference is 0, and the difference value of the second element is 1, 3 The difference value of the # 1 element is −1, and the difference value of the # 4 element is 2, so the value obtained by integrating these values is the gamma correction value. That is, the gamma correction value is calculated as (gamma correction value) = 0 + 1 + (− 1) + 2 = 2. Looking at the table 1101 in 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.

As described above, the gamma correction value calculation circuit 1004
Then, a gamma correction value is calculated for each element selected by the element selection circuit 106 from the reference element gamma correction table and the difference value, and gamma correction is performed by the gamma correction circuit 103 from the calculated gamma correction value for each element. It can be carried out.

As described above, according to the third embodiment, the gamma correction storage circuit 1005 stores the difference between the gamma correction value of the reference element and the gamma correction value of the element adjacent to each other in a predetermined storage capacity. The reference element performs gamma correction using the stored gamma correction value.Other elements calculate the gamma correction value from the value obtained by integrating the difference value up to the element position with the gamma correction value of the reference element. Since the gamma correction is performed by performing the gamma correction, the gamma correction can be performed for each pixel, the deterioration of the image quality can be suppressed, and the gamma correction data for each element can be stored with a small storage capacity.

When the difference value is stored with a predetermined storage capacity, the storage capacity is changed such that the low-gradation side stores it with 4 bits and the other gradations stores with 2 bits. It may be. This is because, as described above, since the gamma correction value of the element tends to fluctuate on the low gradation side, the difference value increases, and when the storage capacity of the difference value is determined in accordance with the difference value of this region, This is because the storage capacity may be wasted. Therefore, as described above, the storage capacity may be changed between the low gradation side and the rest in order to store the data efficiently.

(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 denote the same or corresponding parts, and 1204 denotes a gamma correction value storage circuit 1005.
Gamma correction value calculation circuit 100 based on the value obtained from
4 is a gamma correction value interpolation circuit that calculates an appropriate gamma correction value by an interpolation process using the output of the pattern No. 4 and the pattern value output from the pattern value storage circuit 408.

As described in the second embodiment, if the gamma correction value for the gray chart pattern is stored in the gamma correction value storage circuit 1005 and the gamma correction value is interpolated by interpolation processing, Gamma correction can be performed with a reduced 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 table of FIG. The gamma correction value calculation circuit 1005 calculates the gamma correction value of each element by the method described above. In the case of the table of FIG. 13A, since the first element is the reference element, the difference value from the element position to the gamma correction value of the first element which is the reference element for the second to Nth elements is calculated. By adding the integrated values, a gamma correction value can be calculated as in the table shown in FIG.

The gamma correction value interpolation circuit 1204 interpolates 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. As for this interpolation method, the interpolation processing is performed according to the method described in the second embodiment. On the basis of the gamma correction value interpolated by the gamma correction value interpolation circuit 1204 in this manner, the gamma correction circuit 10
3 allows gamma correction to be performed for each element.

As described above, according to the present embodiment, the gamma correction value of the reference element is stored in the gamma correction storage circuit 1005.
The difference value of the gamma correction value of each element that is discretely stored is stored, the gamma correction is performed for the reference element by the stored gamma correction value, and the gamma correction value interpolation circuit 1204 for the other elements. Gamma correction is performed by calculating an appropriate gamma correction value by interpolation processing.
Gamma correction can be performed for each pixel, so that deterioration in image quality can be suppressed, and gamma correction data for each element can be stored with a smaller storage capacity.

In this embodiment, since the gamma correction curve has a large change in the low gradation part, the gamma correction accuracy is improved by obtaining more data in this area. When storing a gamma correction value for a discrete input value, a pattern of a low gradation part,
That is, more gamma correction values for the pattern in the dark area may be stored.

Although the first element is used as a reference element, any element may be used as a reference element.

Further, instead of using only one reference element, any number of reference elements may be provided. Further, the case where the gamma correction values for the discrete input values are stored and the case where 10 patterns of the gray chart are stored has been described, but the number of patterns is not limited to this. Furthermore, when interpolating gamma correction values, interpolation may be performed not by linear approximation but by a curve such as a quadratic curve.

Embodiment 5 Hereinafter, a gamma correction apparatus according to Embodiment 5 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. However, in the gamma correction value storage circuit 1005, the gamma of the elements adjacent to each other in position is determined. Instead of storing the difference value of the correction value as it is, if the difference value exceeds the capacity for storing the difference value, the next adjacent element stores the value obtained by adding the excess value to the difference value as the difference value. Is different. Hereinafter, the operation will be described in detail.

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 difference value is integrated as it is to calculate the gamma correction value, the original gamma correction value cannot be restored.

For example, as shown in a table 1401 of FIG. 14A, when there is a gamma correction value and a case where a difference value is stored in 4 bits, the difference value of each element is stored in a table 1402 of FIG. As shown. Since 4 bits can store only values from -8 to 7, for example, the gamma correction value of the first element corresponding to the input value 1 is 1
6, the gamma correction value of the second element is 26 and the difference value is 10
Despite this, it exceeds 4 bits and is stored as the difference value 7.

Accordingly, the table 1403 shown in FIG.
As shown in (2), when the gamma correction value is calculated from the difference value with reference to the first element, the gamma correction value corresponding to the input value 1 of the second element is 16 + 7 = 23. The gamma correction value corresponding to the input value 1 of the third element is a value obtained by adding the difference value of the second element to the reference gamma correction value of the first element, and the difference value of the third element is 16 + 7 + (− 4). ) = 19. Similarly, the gamma correction value corresponding to the input value 1 of the fourth element is 17.

As described above, when the difference value exceeds the storage capacity, the excess value becomes an error, which may affect the elements thereafter, and may make it impossible to restore the original gamma correction value. So, 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.

As described above, although the difference value corresponding to the input value 1 of the second element is 10 but can be stored only up to 7, an error of 3 occurs. Therefore, as shown in a table 1502 in FIG. 15A, the error 3 is added to the difference value of the third element and stored. Accordingly, since the difference value of the third element is originally -4, -1 obtained by adding the error 3 and the difference value -4 is the difference value corresponding to the input value 1 of the third element.

When the gamma correction value is restored based on the difference value calculated in this way, the table 15 in FIG.
03, the gamma correction value corresponding to the input value 1 of the second element causes an error because it exceeds the storage capacity of the difference value, but the gamma correction value corresponding to the input value 1 of the third element The value is 22, which is 20 for the fourth and fourth elements, indicating that the original 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, so that even when the difference value exceeds the storage capacity, the gamma can be minimized. Corrections can be made.

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 adjacent in position, the difference value becomes
When the capacity for storing the difference value is exceeded, a value obtained by adding the value exceeding the difference value is stored as a difference value in the next adjacent element, so that gamma correction is 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.

In the present embodiment, as described in the second embodiment, the element characteristic correction value table also includes
By storing the gamma correction values for discrete input data instead of storing the gamma correction values for continuous input data, the storage capacity can be further reduced.

When the gamma correction value for the discrete input value is stored, the gamma correction value for the pattern of the low gradation part, that is, the pattern of the dark area is stored more, so that the gamma correction value for the low gradation part is stored. It is possible to improve the gamma correction accuracy in an area where the change in the gamma correction curve is large. Although the first element is used as a reference element, any element may be used as the reference element. Further, instead of using only one reference element, any number of reference elements may be provided.

(Embodiment 6) Hereinafter, a gamma correction apparatus according to Embodiment 6 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.
Is a gamma for calculating a gamma correction value based on a value output from a gamma correction value storage circuit 1605 which stores an average value of gamma correction values of elements and a difference value between the average value and a gamma correction value of each element. This is a correction value calculation circuit.

In this embodiment, the third to fifth embodiments are described.
As described above, instead of storing the difference value with respect to the reference element, the gamma correction is performed by storing the difference value with the average value of the gamma correction values for each element.

That is, the gamma correction value storage circuit 1605
Calculates and stores the average value of the gamma correction values for each input value and the difference value between the gamma correction value for each element and the above average value. For example, when the gamma correction value for each element is as shown in a table 1701 in FIG. 17A, the average value and the difference value with respect to the average value are calculated in a table 1702 in FIG.
Is calculated as shown in FIG. 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 −5 is stored as the difference value. Similarly, 5 is stored as the difference value for the second element, 1 for the third element, and -1 for the fourth element.
Is stored as the difference value. Thus, the average value and the difference value are calculated and stored in the gamma correction value storage circuit 1605.

Accordingly, the average value of each input value is stored in the average value data of the gamma correction value storage circuit 1605. The difference value Δ1 is the difference value of the first element, and the difference value Δ2 is the difference value of the second element. Is stored as follows. By storing the difference value from the average value as the gamma correction value, the storage capacity can be reduced.

The gamma correction value calculation circuit 1604 calculates the gamma correction value of 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. For example, the first element can create a gamma correction table by adding the difference value Δ1 to the average value data, and the second element can create the gamma correction table by adding the difference value Δ2 to the average value data.

In the method of storing the difference between the average value and the average value as described above, when the difference between the average value and the gamma correction value for each element is large, the storage capacity is slightly increased. Are stored independently, so that when the difference value exceeds the storage capacity, there is an advantage that the error does not affect the gamma correction of other elements.

As described above, according to the present embodiment, the gamma correction value storage circuit 1605 stores the average value of the gamma correction values of the elements and the difference between the average value and the gamma correction value of each element. The gamma correction ground calculation circuit 1604 uses the average value of the gamma correction values output from the gamma correction value storage circuit 1605 and the difference value between the average value and the gamma correction value of each element, for 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, and the gamma correction is performed by the gamma correction circuit 106. The gamma correction value is calculated by adding the values, so that the gamma correction can be performed accurately.In addition, since the difference value of each element is stored independently, if the difference value exceeds the storage capacity, the error may increase. Element It does not affect the gamma correction.

The gamma correction value storage circuit 1605
As described in the second embodiment, instead of storing the gamma correction value for continuous input data, the storage capacity can be reduced by storing the gamma correction value for discrete input values. Can be. Also,
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, so that the gamma correction is performed. The accuracy may be improved.

Embodiment 7 Hereinafter, a gamma correction apparatus according to Embodiment 7 of the present invention will be described with reference to the drawings. FIG. 18 is a block diagram showing a configuration of the gamma correction device according to the seventh embodiment. In FIG.
The same reference numerals as those in FIG.
Reference numeral 04 denotes a gamma correction value calculation circuit that calculates the gamma correction value by receiving the output of the gamma correction value storage circuit 1805 that also stores the data length of the difference value.

The basic operation is the same as that described in the third embodiment. However, instead of storing the difference value in a predetermined storage capacity, the storage capacity is changed according to the magnitude of the difference value. The difference is. Hereinafter, the operation will be described in detail.

As described in the fifth embodiment, when the difference value between the gamma correction values of the elements adjacent in position is calculated, the difference value takes various values. It may be inconvenient to store the value. 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.

For example, as shown in the table of FIG. 19A, when there are gamma correction values for the first element and the second element,
The difference value of the second element is calculated as shown in the table of FIG. FIG. 2 shows the difference value as the data length and the difference value.
The data is sequentially stored as shown in FIG. In the case of FIG. 20,
The data length is stored in 3 bits, and then the difference value is stored.

The data length is 0 when the difference value is 1 bit,
The data length can be stored in 3 bits by storing 1 in the case of 2 bits and 7 in the case of 8 bits. For example, the difference value of the second element corresponding to the input value 0 is 0,
Since the data length can be represented by 1 bit, the data length is stored as 0. Next, the difference value corresponding to the input value 1 is 10 and can be represented by 5 bits, so that the data length is stored as 4. The data length and the difference value calculated in this way are shown in FIG.
Are sequentially stored as shown in FIG.

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 accurately stored, so that the difference value can be stored more flexibly. . As described above, according to the present embodiment, by sequentially storing the data length and the difference value, even if the difference value becomes large, the difference value can be stored accurately, 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 stores
As described in the second embodiment, the storage capacity can be reduced by storing gamma correction values for discrete input values instead of storing gamma correction values for continuous input data. Further, 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 the gamma correction can be improved.

Embodiment 8 Hereinafter, a gamma correction device according to Embodiment 8 of the present invention will be described with reference to the drawings. FIG. 22 is a block diagram illustrating a configuration of a gamma correction device according to the eighth embodiment. In FIG.
Reference numeral 2204 denotes a gamma correction table selection circuit. The gamma correction table storage circuit 2206 includes a plurality of gamma correction tables, and outputs a predetermined data from the gamma selection value storage circuit 2205 that stores the number of the gamma correction table corresponding to each element. Is to select.

In this embodiment, a plurality of gamma correction tables are prepared in advance, and one of the gamma correction tables is selected for each element to reduce the storage capacity of the gamma correction values. For example, the gamma correction table storage circuit 2206 stores N gamma correction tables. Each gamma correction table is numbered, and the gamma correction table is selected by the number for each element, and gamma correction is performed from the selected gamma correction table.

In the gamma selection value storage circuit 2205,
A selection number for selecting a gamma correction table is stored 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 2205 as the first element table selection number.

The gamma correction table selection circuit 2204 selects a gamma correction table of the corresponding element from the gamma correction table storage circuit 2206 with reference to the selection number of the gamma selection value storage circuit 2205. Then, the gamma correction circuit 103 performs gamma correction based on the selected gamma correction table.

By preparing a plurality of gamma correction tables in advance and setting a gamma correction table to be used for each element, the overall storage capacity can be reduced. For example, when preparing a gamma correction table for 640 elements, if a gamma correction table for all elements is prepared individually, 640 tables are required. Some of the 640 elements have gamma characteristics similar to each other. Therefore, if 100 gamma correction tables are sufficient, the gamma correction table can be stored with a capacity of 100/640. In this case, since the capacity of the gamma selection value storage circuit 2205 is small, it can be ignored.

In this case, only the gamma selection table (gamma selection value storage circuit 22) is stored in the ROM of the scanner body.
05) may be stored so that the personal computer has a gamma correction table (gamma correction table storage circuit 2206). This is the RO of the scanner itself
This is because M has a limited capacity, but when it is stored on the personal computer side, a storage capacity much larger than the ROM of the scanner body can be prepared. By providing the personal computer with a correction table in this way, the ROM capacity of the image scanner can be reduced, and more gamma correction tables can be stored.

The table selection number for each element is obtained by first calculating an accurate gamma correction table for each element, and calculating the gamma correction table and the gamma correction table storage circuit 22 in advance.
By selecting a gamma correction table that minimizes the least square sum difference from the gamma correction table prepared in 06 and storing the selection number in the gamma selection table, the gamma correction table can be accurately selected.

Further, as shown in FIG. 23, the gamma correction table storage circuit 2307 may store a reference gamma correction table as a reference and a difference value between each gamma correction table and the reference gamma correction table. Good. By storing the difference value, the storage capacity of the gamma correction table 2307 can be further reduced. As a reference gamma correction table, a gamma correction table with the smallest gamma correction amount is selected. In this case, the gamma correction tables are arranged in ascending order of the 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 is 2
The difference value between the gamma correction table with the smallest gamma correction amount and the gamma correction table with the smallest gamma correction amount is stored. The difference value Δ2 has the third gamma correction table with the smallest gamma correction amount, the second Is stored in such a manner that a difference value from a gamma correction table having a small gamma correction amount is stored.

On the other hand, as the reference gamma correction table, the gamma correction table having 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 the next. The difference value of the gamma correction value of the matching gamma correction table may be stored.

The gamma correction value calculation circuit 2306 can calculate the gamma correction table by adding the difference value to the reference gamma correction table. This is the same as the method described in the third embodiment. For example, when the gamma correction tables are stored in ascending order of the gamma correction amount, the fourth gamma correction table having the smallest gamma correction amount is the difference value Δ1 in the reference gamma correction table.
It is a value obtained by adding the difference value Δ2 and the difference value Δ3. By storing the difference value of the gamma correction table in this way,
The storage capacity can be reduced.

As described above, according to the present embodiment, a plurality of gamma correction tables are stored in advance in the gamma correction table storage circuit 2206, and the gamma selection value storage circuit 22
At 05, the gamma correction table selection information is stored for each element, and the gamma correction table selection circuit 2204 is used to select a gamma correction table corresponding to the table number stored in the corresponding gamma selection value storage circuit 2205. Thus, gamma correction for each element can be performed with a small storage capacity.

Further, in the above configuration, the gamma correction table is stored in the gamma correction table storage circuit 2307 by storing a reference gamma correction table as a reference and a difference value between each gamma correction table and the reference gamma correction table. The storage capacity can be further reduced.

Embodiment 9 Hereinafter, a gamma correction device according to Embodiment 9 of the present invention will be described with reference to the drawings.

FIG. 24 is a block diagram showing the structure of the gamma correction device according to the ninth embodiment. In FIG.
Reference numeral 04 denotes a gamma correction value calculation circuit that calculates a gamma correction value based on a characteristic correction value output from an element characteristic correction value calculation circuit 2405 described later. Reference numeral 2405 denotes a reference stored in an element characteristic correction value storage circuit 2406 described later. An element characteristic correction value calculation circuit 2406 calculates a characteristic correction value of the selected element by adding a value obtained by integrating the difference value up to the element position to the element characteristic correction table. An element characteristic correction value storage circuit stores an output characteristic correction value for an input value.

The basic operation is the same as that of the third embodiment. However, instead of storing a gamma correction table, an element characteristic correction value which is an output characteristic correction value for an element input value before gamma correction is performed. The difference is that values are stored. The characteristics of an ideal element before gamma correction are linear with respect to input data, as shown in FIG. Actual element characteristics deviate from linear characteristics as shown in 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.

As described above, when the characteristic correction value before the gamma correction is stored, compared with the case where the gamma correction value is stored,
The difference value for each element can be reduced. This is because, when gamma correction is performed, the characteristics vary greatly in each element because the characteristics change greatly in the low gradation area, but the element characteristics before gamma correction are such that the output value with respect to the input value is almost linear. Therefore, the characteristic value does not largely change, and the difference value for each element can be reduced.

For example, the characteristic correction value for each element is as shown in a table 2601 in FIG. 26, and is substantially linear with respect to the input value. Accordingly, the difference value between the elements adjacent in position is also as shown in the table 2602 in FIG. 26, and the difference value can be made smaller than when the difference value of the gamma correction value is obtained. In the example of FIG. 26, the difference value is a value between −2 and 1, and the difference value can be expressed by 2 bits, so that the storage capacity of the gamma correction value can be reduced to about ／.

The element characteristic correction value storage circuit 2406 stores a reference element characteristic correction table serving 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 positionally adjacent elements. Are stored in order. In the example shown in FIG. 26, the reference element characteristic correction table stores the element characteristic correction table of the first element, and the difference value Δ1 stores the difference value between the element characteristics of the second element and the first element. Value Δ
In 2, adjacent difference values such as a difference value of element characteristics between the third element and the second element are stored with a predetermined storage capacity.

In the element characteristic correction value calculation circuit 2405, as described in the third embodiment, the element selection circuit 2407
Is calculated by adding a value obtained by integrating the difference value up to the element position to the reference element characteristic correction table stored in the element characteristic correction value storage circuit 2406. Then, the gamma correction value calculation circuit 24
In step 04, a gamma correction value corresponding to the characteristics of the output monitor is calculated for the characteristic correction value for each element calculated by the element characteristic correction value calculation circuit 2405.

For example, when displaying on a monitor having a gamma value of 2.2, a gamma correction value is calculated so as to have a gamma characteristic of the reciprocal of 0.45. In this case, the gamma correction value for the input value is (gamma correction value) = (input value) ^0.45 . Thus, 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.

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 the difference value is stored, as described in the fifth embodiment, the difference value of the characteristic correction value between the elements adjacent in position is not stored as it is, but the difference value is used as the difference value. If the capacity for storing the value is exceeded, the next adjacent element may store a value obtained by adding the exceeded value to the difference value as the difference value. By adding the excess value to the difference value of the next element, data can be restored with a minimum error.

In storing the difference values, as described in the sixth embodiment, instead of storing the difference values of the characteristic correction values between the elements adjacent in position, the element values for each input value are stored. The average value of the characteristic correction values and the difference value between the characteristic correction value and the average value for each element may be stored. By doing so, 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.

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. Good. 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.

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 stores several discrete values. A characteristic correction value for input data may be stored.

When element characteristic values corresponding to discrete input values are stored, as described in the second embodiment, accuracy is improved by storing more data in a low gradation area, that is, in a dark area. be able to. Although the first element is used as a reference element, any element may be used as the reference element. Further, instead of using only one reference element, any number of reference elements may be provided.

[0127]

As described above, according to the gamma correction device according to the first aspect of the present invention, the gamma correction device for correcting the gamma characteristics of a plurality of imaging devices stores the gamma correction values of all the imaging devices. Gamma correction value storage means, a gamma correction value selection 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 selection means for each element. Gamma correction means for performing individual gamma correction is provided, so that gamma correction can be performed for each element to correct the gamma characteristics of the elements, and the effect that more accurate gamma correction can be performed is obtained. Can be

According to the gamma correction device of the second aspect of the present invention, in the gamma correction device of the first aspect, the gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. A gamma correction value for calculating a gamma correction value for each element by performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means. Since the interpolation means is provided, by storing only the gamma correction values for the discrete input values, an effect is obtained that gamma correction can be performed for each element with a small storage capacity.

According to the gamma correction device of the third aspect of the present invention, in the gamma correction device of the first aspect, in the gamma correction device of the first aspect, the gamma correction value storage means includes: When storing a gamma correction value for a discrete input value obtained by reading a predetermined image, the gamma correction value of the low gradation part is stored more, so that the gamma correction of the low gradation part having a large change amount is stored. By storing more values, it is possible to obtain an effect that gamma correction can be performed for each element with a small storage capacity and with high accuracy.

According to the gamma correction device of the fourth aspect of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction value of the reference device and
Gamma correction value storage means for storing the difference value of the gamma correction value between elements adjacent in position with a predetermined storage capacity; and gamma correction value for each element from the gamma correction value stored in the gamma correction value storage means. A gamma correction value calculating means for calculating a reference element using a stored gamma correction value, and for other elements, integrating a gamma correction value of the reference element and a difference value up to the element position to calculate the gamma correction value. Gamma correction means for performing gamma correction for each element from the value, so that the difference value between the gamma correction values of the elements adjacent in position is stored in a predetermined storage capacity, so that the efficiency and the efficiency are reduced. An effect is obtained that gamma correction can be performed for each element with a storage capacity.

According to a fifth aspect of the present invention, in the gamma correction apparatus according to the fourth aspect, the gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. A gamma correction value for calculating a gamma correction value for each element by performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means. Since the interpolation means is provided, the difference value between the gamma correction values of the elements adjacent in position is stored in a predetermined storage capacity, and further, only the gamma correction value for a discrete input value is stored. The effect is obtained that gamma correction can be performed for each element with a small storage capacity.

According to the gamma correction device of the sixth aspect of the present invention, in the gamma correction device of the fourth aspect, the gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. When storing the gamma correction value for, the gamma correction value of the low gradation portion is stored more, so that the gamma correction value of the low gradation portion having a large change amount is stored more, so that less storage is performed. The effect is obtained that the gamma correction can be accurately performed for each element by the capacity.

Further, according to the gamma correction device of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction value of the reference device and
The difference value of the gamma correction value between adjacent elements is stored in a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, the adjacent element adds the excess value to the difference value. A gamma correction value for each element from the gamma correction values stored in the gamma correction value storage means, a stored gamma correction value for a reference element, and a reference gamma correction value for other elements. Gamma correction value calculating means for integrating the gamma correction value of the element and the difference value up to the element position for calculation, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value are provided. By storing the difference value between the gamma correction values of the elements adjacent in position, gamma correction can be performed for each element with a small storage capacity, and the difference value exceeds the capacity for storing the difference value. Effect is obtained in that even if it is possible to suppress the error to a minimum.

According to an eighth aspect of the present invention, in the gamma correction apparatus according to the seventh aspect, the gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. A gamma correction value for calculating a gamma correction value for each element by performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means. Since the interpolation means is provided, even when the difference value exceeds the capacity for storing the difference value, the error can be minimized, and the gamma correction value for the discrete input value is stored. This has the effect of reducing the storage capacity of the gamma correction value.

Further, according to the gamma correction apparatus of the ninth aspect of the present invention, in the gamma correction apparatus of the seventh aspect, the gamma correction value storage means stores the discrete input value obtained by reading a predetermined image. When storing the gamma correction value for, the gamma correction value of the low gradation part is stored more, so even if the difference value exceeds the capacity for storing the difference value, the error is minimized. In addition, by storing more gamma correction values in the low gradation part where the amount of change is large, it is possible to obtain the effect that gamma correction can be performed for each element with small storage capacity and with high accuracy.

According to the gamma correction device of the tenth aspect of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of imaging devices, the average value of the gamma correction values of the devices, the average value thereof, and A gamma correction value storage unit that stores a difference value of the gamma correction value for each element; and a gamma correction value for each element from the gamma correction value stored in the gamma correction value storage unit. Gamma correction value calculation means for calculating from the value obtained by adding the difference value, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value are provided. Since the gamma correction value is calculated by adding the difference value to the gamma correction value, the gamma correction can be performed accurately.

According to the gamma correction device of the present invention, in the gamma correction device of the tenth aspect, the gamma correction value storage means stores the discrete input value obtained by reading a predetermined image. A gamma correction value for calculating a gamma correction value for each element by performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means. Interpolation means are provided, so that a gamma correction value can be calculated by adding a difference value to an average value independently for each element, and accurate gamma correction can be performed. Storing the gamma correction value has the effect of reducing the storage capacity of the gamma correction value.

Further, according to the gamma correction apparatus of the twelfth aspect of the present invention, in the gamma correction apparatus of the tenth aspect, the gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. When storing the gamma correction value for, the gamma correction value for the low gradation part is stored more, so the difference value is added to the average value independently for each element to calculate the gamma correction value. Gamma correction can be performed accurately, and the storage capacity can be accurately reduced by storing more low-gradation portions having a large change amount among the gamma correction values for discrete input values. Is obtained.

According to the gamma correction device of the thirteenth aspect of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction value of the reference device and the gamma correction value of the positionally adjacent device are compared. Gamma correction value storage means for storing the difference value of the gamma correction value and the data length thereof,
The gamma correction value for each element is calculated from the gamma correction value stored in the gamma correction value storage means, the reference element performs gamma correction using the stored gamma correction value, and the other elements perform gamma correction for the gamma correction value of the reference element. Gamma correction value calculation means for calculating from a value obtained by integrating the difference values up to the position, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value, so that they are adjacent to each other in position. By efficiently storing the difference value of the gamma correction value of the element according to the magnitude of the difference value, an effect is obtained that gamma correction can be performed for each element with a small storage capacity.

According to a gamma correction device of the present invention, in the gamma correction device of the thirteenth aspect, the gamma correction value storage means stores a discrete input value obtained by reading a predetermined image. A gamma correction value for calculating a gamma correction value for each element by performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the gamma correction value storage means. Since the interpolation means is provided, the difference value of the gamma correction value of the element adjacent in position is efficiently stored in accordance with the magnitude of the difference value, and only the gamma correction value for the discrete input value is stored. Has the effect that gamma correction can be performed for each element with a smaller storage capacity.

According to the gamma correction device of the present invention, the gamma correction value storage means may store the discrete input value obtained by reading a predetermined image. When storing the gamma correction value for, the gamma correction value of the low gradation portion is stored more, so that the gamma correction value of the low gradation portion having a large change amount is stored to reduce the storage capacity. Thus, an effect that gamma correction can be performed for each element with high accuracy can be obtained.

Further, according to the gamma correction device of the present invention, 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, A gamma correction table selection information storage means for storing selection information for selecting a gamma correction table for each element; a gamma correction table corresponding to each element from the gamma correction table storage means and the gamma correction table selection information storage means And a gamma correction unit for performing gamma correction based on the selected gamma correction table.By storing only the selection information of the gamma correction table corresponding to each element, The effect that the storage capacity can be reduced is obtained.

According to a gamma correction device of the present invention, in the gamma correction device of the sixteenth aspect, the gamma correction table storage means includes a gamma correction table having the smallest gamma correction amount, or The gamma correction table having the largest amount of gamma correction is stored as the reference gamma correction table, and other gamma correction tables have the same gamma correction amount when the reference gamma correction table uses the gamma correction table having the smallest gamma correction amount. When the gamma correction tables are arranged in ascending order, the difference value between the gamma correction values adjacent to each other is stored.
When the gamma correction table having the largest gamma correction amount is used as the reference gamma correction table, when the gamma correction tables are arranged in the descending order of the gamma correction amount, the difference value of the gamma correction value adjacent to the order is stored. Since the gamma correction table calculating means for calculating the gamma correction table from the reference gamma correction table and the difference value is provided, when storing the plurality of gamma correction tables in the gamma correction table storage means, Storing the difference value between the close gamma correction tables has the effect of reducing the storage capacity of the gamma correction table storage means.

According to the gamma correction apparatus of the eighteenth aspect of the present invention, in the gamma correction apparatus of the sixteenth aspect, the gamma correction table selecting means stores the gamma correction table of the element and the gamma correction table. The gamma correction table that minimizes the least square sum of the gamma correction values is selected from among the plurality of gamma correction tables stored in the means. By storing only the selection information of the gamma correction table, the storage capacity can be reduced, and the optimal gamma correction table can be selected accurately.

According to the gamma correction device of the nineteenth aspect of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of image pickup devices, the device characteristic correction value of the reference device and the device characteristically adjacent to the reference device are corrected. Element characteristic correction value storage means for storing a characteristic correction value before gamma correction with a predetermined storage capacity for a difference value between element characteristic correction values, and an element based on the element characteristic correction value stored in the element characteristic correction value storage means. For each element characteristic correction value, the reference element calculates a gamma correction value based on the stored element characteristic correction value, and for other elements, a value obtained by integrating the difference value up to the element position with the element characteristic correction value of the reference element. A gamma correction value calculating means for calculating a gamma correction value for each element from the calculated characteristic correction value for each element, and a gamma correction value calculating means for calculating a gamma correction value for each element from the calculated gamma correction value. Having assumed that a gamma correction unit for performing gamma correction, by storing the difference value of the difference is smaller before gamma correction characteristic correction value in characteristics among elements,
The effect is obtained that gamma correction can be performed for each element with a smaller storage capacity.

According to a gamma correction device of the present invention, in the gamma correction device of the nineteenth aspect, the element characteristic storage means stores an element characteristic correction value of a positionally adjacent element. The difference value is stored in a predetermined storage capacity, and when the difference value exceeds the predetermined storage capacity, an adjacent element is added with the value exceeding the difference value and stored. By storing the difference value of the characteristic correction value before the gamma correction with a small characteristic difference with a predetermined storage capacity, it is possible to perform the gamma correction more efficiently for each element with a smaller storage capacity.

According to the gamma correction apparatus of the twenty-first aspect of the present invention, in the gamma correction apparatus of the nineteenth aspect, the element characteristic correction value storage means stores the average value of the element characteristic correction values of the elements. A difference value between the average value and the element characteristic correction value for each element, and the element characteristic correction value calculation means calculates a value obtained by adding the difference value for each element to the average value of the element characteristic correction value for each element. Since the element characteristic correction value is calculated from, the storage capacity can be reduced by storing the difference value of the characteristic correction value before gamma correction where the characteristic difference between the elements is small, and the difference value can be reduced. Has an effect that even if the data exceeds the capacity for storing the difference value, the error can be minimized.

According to the gamma correction device of the present invention, in the gamma correction device of the nineteenth aspect, the element characteristic storage means stores an element characteristic correction value of a positionally adjacent element. Is stored together with the data length, so that the difference between the characteristic correction values before gamma correction, in which the characteristic difference between the elements is small, is stored, so that the storage capacity can be reduced. Since the characteristic correction value is calculated by independently adding the difference value to the average value for each element, and the gamma correction value is calculated from the characteristic correction value, an effect that gamma correction can be accurately performed can be obtained. .

According to the gamma correction device of the present invention, the element characteristic correction value storage means may be a discrete input device that reads a predetermined image. The element characteristic correction value interpolating means stores an element characteristic correction value for the value, and performs an interpolation process based on the input value of the predetermined image and the element characteristic correction value stored in the element characteristic correction value storage means. Since the element characteristic correction value is calculated for each element, it is necessary to store the difference value of the characteristic correction value before the gamma correction in which the characteristic difference between the elements is small, and to store the characteristic correction value for a discrete input value. Thereby, an effect that the storage capacity can be further reduced can be obtained.

According to a gamma correction apparatus according to claim 24 of the present invention, in the gamma correction apparatus according to claim 19, the element characteristic correction value storage means includes a discrete input device that reads a predetermined image. When the element characteristic correction value for the value is stored, the element characteristic correction value of the low gradation part is stored more, so that the difference value of the characteristic correction value before gamma correction where the characteristic difference between the elements is small is calculated. By storing the data, the storage capacity can be reduced, and by storing more characteristic correction values of the low gradation part where the amount of change becomes large after the gamma correction, gamma correction can be accurately performed for each element with a small storage capacity. This has the effect.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a gamma correction device according to a first embodiment 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 block diagram illustrating a configuration of a gamma correction device according to a second embodiment of the present invention.

FIG. 5 is a diagram illustrating an example of a gray chart used for calculating a gamma correction value.

FIG. 6 is a diagram showing an example of gamma correction values for ten patterns of a gray chart.

FIG. 7 is a diagram for explaining an interpolation process for linearly interpolating between data.

FIG. 8 is a diagram showing an example of a case where an ideal gamma curve having a gamma of 2.2 in a gamma correction curve is linearly approximated by ten discrete data.

FIG. 9 is a diagram illustrating an example of an interpolation process that takes a larger number of data in a low gradation area and minimizes an error from an ideal gamma curve.

FIG. 10 is a block diagram illustrating a configuration of a gamma correction device according to a third embodiment 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 illustrating a configuration of a gamma correction device according to a fourth embodiment 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 an interpolation method by a gamma correction device according to a fifth embodiment of the present invention.

FIG. 15 is a diagram illustrating 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 illustrating a configuration of a gamma correction device according to a seventh embodiment of the present invention.

FIG. 19 is a diagram for explaining a recording method in the gamma correction value storage circuit of the gamma correction device according to the seventh embodiment.

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 when the data length and the gamma correction value of the gamma correction value according to the seventh embodiment are sequentially stored.

FIG. 22 is a block diagram illustrating a configuration of a gamma correction device according to an eighth embodiment of the present invention.

FIG. 23 is a block diagram showing a configuration of a modified example of the gamma correction device according to the eighth embodiment.

FIG. 24 is a block diagram illustrating a configuration of a gamma correction device according to Embodiment 9 of the present invention.

FIG. 25 is a diagram illustrating 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 according to the seventh embodiment.

FIG. 27 is a diagram for conceptually explaining a gamma correction method using a ROM storing a gamma correction table.

FIG. 28 is a block diagram illustrating a configuration of a conventional gamma correction device.

FIG. 29 is a diagram for explaining a method of gamma correction by a conventional gamma correction device.

FIG. 30 is a diagram for explaining a difference value calculation method in a conventional gamma correction device.

[Explanation of symbols]

101, 204 Image sensor 102 A / D converter 103 Gamma correction circuit 104, 2204, 2304 Gamma correction table selection circuit 105, 1005, 1605, 1805 Gamma correction value storage circuit 106 Element selection circuit 201 Document to be read 202 Illumination 203 Lens 404, 1204 Gamma correction value interpolation circuit 408 Pattern value storage circuit 1004, 1604, 1804, 2404 Gamma correction value calculation circuit 2205, 2305 Gamma selection value storage circuit 2206, 2307 Gamma correction table storage circuit 2405 Element characteristic correction value calculation circuit 2406 Element characteristic correction value Storage circuit 2801 Input terminal 2802 Input selection unit 2803 Gamma characteristic correction unit 2804 Characteristic selection unit 2805 Microprocessor 2806 Data storage unit

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[Procedure amendment]

[Submission date] June 29, 2001 (2001.6.2
9)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Claim 7

[Correction method] Change

[Correction contents]

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] Claim 10

[Correction method] Change

[Correction contents]

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] Claim 13

[Correction method] Change

[Correction contents]

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] Claim 19

[Correction method] Change

[Correction contents]

[Procedure amendment 6]

[Document name to be amended] Statement

[Correction target item name] Claim 21

[Correction method] Change

[Correction contents]

[Procedure amendment 7]

[Document name to be amended] Statement

[Correction target item name] 0018

[Correction method] Change

[Correction contents]

Further, the gamma correction apparatus according to claim 4 of the present invention, the gamma correction apparatus for correcting the gamma characteristics of a plurality of imaging elements, and a gamma correction value of the reference element, it
And the difference value of the gamma correction value of each other element adjacent to, respectively positionally, using the gamma correction value storage means for storing in a predetermined storage capacity, the gamma correction value criteria elements are stored, otherwise in the element, against the gamma correction value of the reference element
By each product <br/> calculate the difference value of the element up to the present position of the device, and the gamma correction value calculating means for calculating the gamma correction value for each element, for each element from the gamma correction value calculated above Gamma correction means for performing gamma correction.

[Procedure amendment 8]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction contents]

Further, the gamma correction apparatus according to claim 7 of the present invention, the gamma correction apparatus for correcting the gamma characteristics of a plurality of imaging elements, and a gamma correction value of the reference element, it
And the difference value of the gamma correction value of each other element adjacent positionally, respectively, stored in a predetermined storage capacity, storage in excess of storage in which the difference value is predetermined, said in adjacent elements <br / > gamma correction value storage means for adding and storing the excess value of the storage capacity in the difference value determined above in advance, using the gamma correction value criteria elements are stored, and in the other element, the reference element containing up to the present position of the element in the gamma correction value
By integrating the difference value of the child respectively, gamma per element
The apparatus includes gamma correction value calculation means for calculating a correction value, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value.

[Procedure amendment 9]

[Document name to be amended] Statement

[Correction target item name] 0024

[Correction method] Change

[Correction contents]

According to a tenth aspect of the present invention, there is provided a gamma correction apparatus for correcting a gamma characteristic of a plurality of image pickup devices, wherein an average value of a gamma correction value of each element for each input , and a gamma correction value for each of the one element and the <br/> gamma correction value storage means for storing a difference value, a gamma correction value for each element child, the average value of the gamma correction value, the difference value of each element Gamma correction value calculating means for calculating by adding
Gamma correction means for performing gamma correction for each element from the calculated gamma correction value.

[Procedure amendment 10]

[Document name to be amended] Statement

[Correction target item name] 0027

[Correction method] Change

[Correction contents]

Further, the gamma correction apparatus according to claim 13 of the present invention, the gamma correction apparatus for correcting the gamma characteristics of a plurality of imaging elements, and a gamma correction value of the reference element, its
A difference value between the gamma correction value of each other element adjacent to respectively positionally, and the gamma correction value storage means for storing the data length of said difference values, the gamma correction by the gamma correction value criteria elements are stored was carried out, except in the element by integrating a difference value of the element up to the present position of the element in the gamma correction value of the reference element, respectively, the gamma correction value to <br/> calculating the gamma correction value for each element A gamma correction unit for performing gamma correction for each element from the calculated gamma correction value.

[Procedure amendment 11]

[Document name to be amended] Statement

[Correction target item name] 0033

[Correction method] Change

[Correction contents]

A gamma correction device according to a nineteenth aspect of the present invention is a gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, wherein the input of the reference device before the gamma correction is performed.
And the element characteristic correction value which is an output characteristic correction value for a value, its
At respectively positionally adjacent elements to each other, gamma complement
And the difference value of the element characteristic correction value which is an output characteristic correction value for the positive previous input value, advance the device characteristic correcting value storing means for memorize a storage capacity determined, device characteristics criteria elements are stored corrected calculating a gamma correction value by a value, the other elements, the element characteristic correction value of the reference element to the position of the element
The difference value of the element present by integrating respectively, containing
Element characteristic correction value calculation means for calculating a gamma correction value for each child; gamma correction value calculation means for calculating a gamma correction value for each element from the calculated characteristic correction value for each element; and gamma correction value calculated from the calculated gamma correction value. Gamma correction means for performing gamma correction for each element.

[Procedure amendment 12]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction contents]

In the gamma correction apparatus according to a twenty-first aspect of the present invention, in the gamma correction apparatus according to the nineteenth aspect, the element characteristic correction value storage means stores the average value of the element characteristic correction values of the elements, storing the average value and the difference value of the element characteristic correction value for each element, the element characteristic compensation value calculation means from a value obtained by adding the difference value of each element to the average value of the element characteristic correction value for each element An element characteristic correction value is calculated.

[Procedure amendment 13]

[Document name to be amended] Statement

[Correction target item name] 0052

[Correction method] Change

[Correction contents]

For example, as shown in FIG. 8, when the ideal gamma curve whose gamma correction curve has a value of gamma 2.2 is linearly approximated by ten discrete data, the gradation is uniformly set to X.
It can be seen that in the case of approximating by dividing by (0) to X (9), the error between the gamma correction value interpolated in the low gradation area and the ideal gamma curve increases. This is because the gamma correction curve greatly changes in a low gradation portion. Therefore, as shown in FIG. 9, it can be seen that the error from the ideal gamma curve can be minimized by increasing the number of data in the low gradation area even for the same 10 data.

[Procedure amendment 14]

[Document name to be amended] Statement

[Correction target item name] 0069

[Correction method] Change

[Correction contents]

(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 denote the same or corresponding parts, and 1204 denotes a gamma correction value storage circuit 1005.
Gamma correction value calculation circuit 100 based on the value obtained from
4 and output a gamma correction value interpolation circuit for calculating an appropriate gamma correction values by interpolation processing using the pattern value storage circuit 40 eight et output pattern value.

[Procedure amendment 15]

[Document name to be amended] Statement

[Correction target item name] 0070

[Correction method] Change

[Correction contents]

As described in the second embodiment, if the gamma correction value for the gray chart pattern is stored in the gamma correction value storage circuit 1005 and the gamma correction value is interpolated by interpolation processing, Gamma correction can be performed with a reduced 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 table of FIG. The gamma correction value calculation circuit 1005 calculates the gamma correction value of each element by the method described above. In the case of the table of FIG. 13A, since the first element is the reference element, the difference value from the element position to the gamma correction value of the first element which is the reference element for the second to Nth elements is calculated. by adding the integrated value, it can be calculated gamma correction values as a table shown in Figure 13 (b).

[Procedure amendment 16]

[Document name to be amended] Statement

[Correction target item name] 0085

[Correction method] Change

[Correction contents]

When the gamma correction value for the discrete input value is stored, the gamma correction value for the pattern of the low gradation part, that is, the pattern of the dark area is stored more, so that the gamma correction value for the low gradation part is stored. It is possible to improve the gamma correction accuracy in an area where the change in the gamma correction curve is large. Although the first element is used as a reference element, any element may be used as the reference element. Furthermore, also the reference element instead of only one, may have a reference element nothing points.

[Procedure amendment 17]

[Document name to be amended] Statement

[Correction target item name] 0092

[Correction method] Change

[Correction contents]

As described above, according to the present embodiment, the gamma correction value storage circuit 1605 stores the average value of the gamma correction values of the elements and the difference between the average value and the gamma correction value of each element. In the gamma correction value calculation circuit 1604, each element is calculated using 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, and the gamma correction is performed by the gamma correction circuit 106. The gamma correction value is calculated by adding the values, so that the gamma correction can be performed accurately.In addition, since the difference value of each element is stored independently, if the difference value exceeds the storage capacity, the error may increase. Element It does not affect the gamma correction.

[Procedure amendment 18]

[Document name to be amended] Statement

[Correction target item name] 0098

[Correction method] Change

[Correction contents]

The data length is 0 when the difference value is 1 bit,
The data length can be stored in 3 bits by storing 1 in the case of 2 bits, 7 in the case of 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 expressed by 1 bit, so that the data length is stored as 0. Next, the difference value corresponding to the input value 1 is 10,
Since the data length can be represented by 5 bits, the data length is stored as 4. The data length and the difference value calculated in this way are shown in FIG.
As shown in FIG.

[Procedure amendment 19]

[Document name to be amended] Statement

[Correction target item name] 0101

[Correction method] Change

[Correction contents]

Embodiment 8 Hereinafter, a gamma correction device according to Embodiment 8 of the present invention will be described with reference to the drawings. FIG. 22 is a block diagram illustrating a configuration of a gamma correction device according to the eighth embodiment. In FIG.
Reference numeral 2204 denotes a gamma correction table selection circuit, which outputs the gamma correction table storage circuit 2206 including a plurality of gamma correction tables and the gamma selection value storage circuit 2205 that stores the number of the gamma correction table corresponding to each element .
The predetermined data is selected from the output .

[Procedure amendment 20]

[Document name to be amended] Statement

[Correction target item name] 0103

[Correction method] Change

[Correction contents]

In the gamma selection value storage circuit 2205,
A selection number for selecting a gamma correction table is stored for each element. For example, so that No. 1 element may select a gamma correction table 3, it is stored in the gamma selection value storage circuit 2205 to select No. 3 as No. 1 element table selection number.

[Procedure amendment 21]

[Document name to be amended] Statement

[Correction target item name] 0104

[Correction method] Change

[Correction contents]

The gamma correction table selection circuit 2204 selects a gamma correction table of the corresponding element from the gamma correction table storage circuit 2206 with reference to the selection number of the gamma selection value storage circuit 2205. Then, in the gamma correction circuit 103, based on the selected gamma correction table,
Perform gamma correction on.

[Procedure amendment 22]

[Document name to be amended] Statement

[Correction target item name] 0105

[Correction method] Change

[Correction contents]

By preparing a plurality of gamma correction tables in advance and setting a gamma correction table to be used for each element, the overall storage capacity can be reduced. For example, when preparing a gamma correction table for 640 elements, if a gamma correction table for all elements is prepared individually, 640 tables are required. Some of the 640 elements have gamma characteristics similar to each other. Therefore, if 100 gamma correction tables are sufficient, the gamma correction table can be stored with a capacity of 100/640. In this case, the capacity of the gamma selection value storage circuit 2205 can be ignored because it is small.

[Procedure amendment 23]

[Document name to be amended] Statement

[Correction target item name] 0106

[Correction method] Change

[Correction contents]

In this case, only the gamma selection table (gamma selection value storage circuit 22) is stored in the ROM of the scanner body.
05) may be stored so that the personal computer has a gamma correction table (gamma correction table storage circuit 2206). This is the RO of the scanner itself
This is because M has a limited capacity, but when it is stored on the personal computer side, a storage capacity much larger than the ROM of the scanner body can be prepared. Thus by providing a correction table on the PC side, and at the same time to reduce the ROM capacity of the image scanner, it is possible to store more gamma correction table.

[Procedure amendment 24]

[Document name to be amended] Statement

[Correction target item name] 0108

[Correction method] Change

[Correction contents]

Further, as shown in FIG. 23, the gamma correction table storage circuit 2307 may store a reference gamma correction table as a reference and a difference value between each gamma correction table and the reference gamma correction table. Good. By storing the difference value, the storage capacity of the gamma correction table 2307 can be further reduced. As a reference gamma correction table, a gamma correction table with the smallest gamma correction amount is selected. In this case, the gamma correction tables are arranged in ascending order of the 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 is 2
The difference value between the gamma correction table with the smallest gamma correction amount and the gamma correction table with the smallest gamma correction amount is stored. The difference value Δ2 has the third gamma correction table with the smallest gamma correction amount, the second the difference value between the small gamma correction table having the gamma correction amount is stored, will be stored and so on.

[Procedure amendment 25]

[Document name to be amended] Statement

[Correction target item name] 0126

[Correction method] Change

[Correction contents]

When element characteristic values corresponding to discrete input values are stored, as described in the second embodiment, accuracy is improved by storing more data in a low gradation area, that is, in a dark area. be able to. Although the first element is used as a reference element, any element may be used as the reference element. Moreover, the reference element instead of only one, may have a reference element nothing points.

[Procedure amendment 26]

[Document name to be amended] Statement

[Correction target item name] 0130

[Correction method] Change

[Correction contents]

According to the gamma correction device of the fourth aspect of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction value of the reference device and
And the difference value of the gamma correction value of each other element positioned contiguous respectively, using the gamma correction value storage means for storing in a predetermined storage capacity, the gamma correction value criteria elements are stored, the other the device, the gamma correction value of the reference element
By respectively <br/> integrates the difference value of the element up to the present position of the device, and the gamma correction value calculating means for calculating the gamma correction value for each element, gamma for each element from the gamma correction value calculated above Gamma correction means for performing the correction, so that the difference value of the gamma correction value of the element adjacent in position is stored in a predetermined storage capacity, so that each element can be efficiently and individually stored with a small storage capacity. The effect that gamma correction can be performed is obtained.

[Procedure amendment 27]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

Further, according to the gamma correction device of the present invention, in the gamma correction device for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction value of the reference device and
And the difference value of the gamma correction value of each other element positioned contiguous respectively, and stored in a predetermined storage capacity, storage in excess of storage in which the difference value is determined in advance, above the difference in the adjacent elements using a gamma correction value storage means for adding and storing a predetermined excess value of the storage capacity, the gamma correction value criteria elements are stored, and in the other element,
Be present to the position of the element in the gamma correction value of the reference element
That difference value of the element to that accumulating each, moths per element
Gamma correction value calculating means for calculating the gamma correction value, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. By storing the difference value, gamma correction can be performed for each element with a small storage capacity, and even if the difference value exceeds the capacity for storing the difference value, the error can be minimized. Is obtained.

[Procedure amendment 28]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

According to the gamma correction apparatus of the tenth aspect of the present invention, in the gamma correction apparatus for correcting the gamma characteristics of a plurality of image pickup devices, the average value of the gamma correction value of each element for each input , and and storing the difference value between the average value and the gamma correction value for each of the one element the gamma correction value storage means, a gamma correction value for each element child, the average value of the gamma correction value, adding the difference value of each element Gamma correction value calculation means for calculating the gamma correction value and gamma correction means for performing gamma correction for each element from the calculated gamma correction value, so that the difference value is added to the average value independently for each element. Thus, the gamma correction value is calculated, and thus the gamma correction can be performed accurately.

[Procedure amendment 29]

[Document name to be amended] Statement

[Correction target item name]

[Correction method] Change

[Correction contents]

According to the gamma correction apparatus of the thirteenth aspect of the present invention, in the gamma correction apparatus for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction value of the reference device and the gamma correction values of the devices which are positioned adjacent to each other. and How to difference value between the gamma correction values, and the gamma correction value storage means for storing the data length of said difference values, performs gamma correction by the gamma correction value criteria elements are stored, the reference in the other element difference value of the element <br/> up to the present position of the element in the gamma correction value of the element by integrating each gamma complement of each element
A gamma correction value calculating unit that calculates a positive value and a gamma correction unit that performs gamma correction for each element from the calculated gamma correction value are provided, so that the difference between the gamma correction values of the elements adjacent in position is determined. By efficiently storing the value according to the magnitude of the difference value, an effect is obtained that gamma correction can be performed for each element with a small storage capacity.

[Procedure amendment 30]

[Document name to be amended] Statement

[Correction target item name] 0145

[Correction method] Change

[Correction contents]

Further, according to the gamma correction apparatus according to the nineteenth aspect of the present invention, in the gamma correction apparatus for correcting the gamma characteristics of a plurality of image pickup devices, the gamma correction of the reference element before the gamma correction is performed.
And the element characteristic correction value which is an output characteristic correction value for the input value, at each position to adjacent elements each other, moth
And the difference value of the element characteristic correction value which is an output characteristic correction value for the input value before comma correction, and the element characteristic correction value storing means for memorize in a predetermined storage capacity, device characteristics criteria elements are stored calculating a gamma correction value by the correction value, and in the other element, the difference value of the element up to the present position <br/> location of the element in the element characteristic correction value of the reference element to be integrated respectively
In the element characteristic correction value calculating means for calculating the gamma correction value for each element, and a gamma correction value calculating means for calculating the gamma correction value for each element from the characteristic correction value of each element calculated above, the gamma correction calculated above Gamma correction means for performing gamma correction for each element from the value, so that the difference between the characteristic correction values before gamma correction, in which the characteristic difference between the elements is small, is stored. An effect is obtained that gamma correction can be performed for each element.

[Procedure amendment 31]

[Document name to be amended] Statement

[Correction target item name] 0147

[Correction method] Change

[Correction contents]

According to the gamma correction apparatus of the twenty-first aspect of the present invention, in the gamma correction apparatus of the nineteenth aspect, the element characteristic correction value storage means stores the average value of the element characteristic correction values of the elements. stores the difference value between the average value and the element characteristic correction value for each element, the element characteristic correction value calculation unit, by adding the difference value of each element to the average value of the element characteristic correction value for each element Since the element characteristic correction value is calculated from the value, the storage capacity can be reduced by storing the difference value of the characteristic correction value before gamma correction, in which the characteristic difference between the elements is small. Even when the value exceeds the capacity for storing the difference value, the effect of minimizing the error can be obtained.

Claims (24)

[Claims] 1. A gamma correction device for correcting gamma characteristics of a plurality of image sensors, a gamma correction value storage means for storing gamma correction values of all image sensors, and a gamma correction for each element from the gamma correction value storage means. Gamma correction means comprising: a gamma correction value selection means for selecting a value; and gamma correction means for performing individual gamma correction for each element using the gamma correction value selected by the gamma correction value selection means. apparatus. 2. The gamma correction device according to claim 1, wherein said gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating means for performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the device and calculating a gamma correction value for each element. 3. The gamma correction device according to claim 1, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image.
A gamma correction device storing more gamma correction values for a low gradation part. 4. A gamma correction device for correcting gamma characteristics of a plurality of imaging devices, wherein a difference value between a gamma correction value of a reference device and a gamma correction value of a device adjacent in position is stored with a predetermined storage capacity. A gamma correction value storage unit that performs gamma correction values for each element from the gamma correction values stored in the gamma correction value storage unit, a reference element uses a stored gamma correction value, and a reference element uses the stored gamma correction value for other elements. Gamma correction value calculating means for calculating a gamma correction value by integrating the difference value up to the element position, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. Gamma correction device. 5. The gamma correction device according to claim 4, wherein said gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image, and said gamma correction value storage means. A gamma correction value interpolating means for performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the device and calculating a gamma correction value for each element. 6. The gamma correction device according to claim 4, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image.
A gamma correction device storing more gamma correction values for a low gradation part. 7. A gamma correction device for correcting 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 in position is 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 the value exceeding the difference value in an adjacent element; and a gamma correction value stored in the gamma correction value storage means. The gamma correction value is calculated by integrating the gamma correction value of each element from the reference element, using the stored gamma correction value for the reference element, and adding the difference value up to the element position to the gamma correction value of the reference element for other elements. A gamma correction device comprising: a calculation unit; and a gamma correction unit that performs gamma correction for each element from the calculated gamma correction value. 8. The gamma correction device according to claim 7, wherein said gamma correction value storage means stores a gamma correction value corresponding to a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating means for performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the device and calculating a gamma correction value for each element. 9. The gamma correction device according to claim 7, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image.
A gamma correction device storing more gamma correction values for a low gradation part. 10. A gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, wherein a gamma correction value storing an average value of gamma correction values of the devices and a difference value between the average value and a gamma correction value of each device. Storage means; gamma correction value calculation means for calculating a gamma correction value for each element from the gamma correction value stored in the gamma correction value storage means, and a value obtained by adding a difference value for each element to an average value of the gamma correction values. A gamma correction device for performing gamma correction for each element from the calculated gamma correction value. 11. The gamma correction device according to claim 10, wherein said gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating means for performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the device and calculating a gamma correction value for each element. 12. The gamma correction device according to claim 10, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image.
A gamma correction device storing more gamma correction values for a low gradation part. 13. A gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, comprising: a gamma storing a difference value between a gamma correction value of a reference device, a gamma correction value of a positionally adjacent device, and a data length thereof. A gamma correction value for each element from the gamma correction value stored in the gamma correction value storage means, a gamma correction for the reference element using the stored gamma correction value, and a reference value for the other elements. Gamma correction value calculating means for calculating from a value obtained by integrating the difference value up to the element position with the gamma correction value of the element; and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. Gamma correction device. 14. The gamma correction device according to claim 13, wherein the gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image. A gamma correction value interpolating means for performing an interpolation process from an input value of a predetermined image and a gamma correction value stored in the device and calculating a gamma correction value for each element. 15. The gamma correction device according to claim 13, wherein said gamma correction value storage means stores a gamma correction value for a discrete input value obtained by reading a predetermined image.
A gamma correction device storing more gamma correction values for a low gradation part. 16. A gamma correction device for correcting gamma characteristics of a plurality of image pickup 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, 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, and a selected gamma correction table Gamma correction means for performing gamma correction by using a gamma correction device. 17. The gamma correction apparatus according to claim 16, wherein said gamma correction table storage means uses a gamma correction table with the smallest gamma correction amount or a gamma correction table with the largest gamma correction amount as a reference gamma correction table. When the reference gamma correction table uses the gamma correction table with the smallest gamma correction amount, the other gamma correction tables include gamma correction tables arranged in the order of the smallest gamma correction amount and the adjacent gamma correction tables. The difference value between the correction values is stored. On the other hand, when the gamma correction table having the largest gamma correction amount is used as the reference gamma correction table, the order is adjacent when the gamma correction tables are arranged in descending order of the gamma correction amount. The difference value of the gamma correction value is stored, and the reference gamma correction table Gamma correction apparatus characterized by and a partial value with a gamma correction table calculating means for calculating the gamma correction table. 18. A gamma correction apparatus according to claim 16, wherein said gamma correction table selecting means performs gamma correction using a gamma correction table of the element and a plurality of gamma correction tables stored in the gamma correction table storage means. A gamma correction device, wherein a gamma correction table that minimizes the least square sum of values is selected. 19. A gamma correction device for correcting gamma characteristics of a plurality of image pickup devices, wherein a storage value having a predetermined difference value between an element characteristic correction value of a reference element and an element characteristic correction value of a positionally adjacent element. And an element characteristic correction value storage unit for storing a characteristic correction value before gamma correction, and an element characteristic correction value for each element from the element characteristic correction value stored in the element characteristic correction value storage unit. An element characteristic correction value calculating means for calculating a gamma correction value based on the element characteristic correction value, and for other elements, calculating from a value obtained by integrating a difference value up to an element position with the element characteristic correction value of the reference element. Gamma correction value calculating means for calculating a gamma correction value for each element from characteristic correction values for each element, and gamma correction means for performing gamma correction for each element from the calculated gamma correction value. Gamma correction device according to claim. 20. The gamma correction device according to claim 19, wherein said element characteristic storage means stores a difference value between element characteristic correction values of elements adjacent in position with a predetermined storage capacity, and stores the difference value. A gamma correction device characterized in that when a predetermined storage capacity is exceeded, an adjacent element adds and stores the excess value to a difference value. 21. The gamma correction device according to claim 19, wherein said element characteristic correction value storage means stores an average value of the element characteristic correction values of the elements, and a difference value between the average value and the element characteristic correction value of each element. Wherein the element characteristic correction value calculation means calculates an element characteristic correction value from a value obtained by adding a difference value for each element to an average value of the element characteristic correction values for each element. . 22. A gamma correction apparatus according to claim 19, wherein said element characteristic storage means stores a difference value between element characteristic correction values of elements adjacent in position together with a data length thereof. Correction device. 23. The gamma correction apparatus according to claim 19, wherein said element characteristic correction value storage means stores an element characteristic correction value corresponding to a discrete input value obtained by reading a predetermined image, and wherein said element characteristic correction value interpolation is performed. The gamma correction unit 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 unit. apparatus. 24. The gamma correction device according to claim 19, wherein said element characteristic correction value storage means stores the element characteristic correction value for a discrete input value obtained by reading a predetermined image. A gamma correction device for storing more element characteristic correction values.