JP2004336243A - Correction apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To correct ununiformity among a plurality of imaging regions in real time by quickly coping with dynamic variations such as a camera-shake or the like of an imaging apparatus. <P>SOLUTION: The correction apparatus is provided with: a plurality of level adjustment means 113, 114 for respectively independently adjusting a level of a plurality of imaging signals outputted from a plurality of output terminals; an output level detection means 116 for detecting an output level of a plurality of the level adjustment means; a camera-shake amount detection means 121 for detecting a camera-shake of the imaging apparatus; and a correction coefficient decision means 117 for deciding a correction coefficient to decrease a level difference of each imaging signal on the basis of a result of detection of the output level detection means, and the correction coefficient decision means 117 gives the decided correction coefficient to the level adjustment means 113, 114 so as to decreasingly adjust the level differences of each imaging signal thereby decreasingly adjusting the level difference of each imaging signal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a correction device, in particular, an imaging surface divided into a plurality of regions, an amplifier for amplifying an imaging signal in each region, and a solid-state imaging device having a plurality of imaging signal output terminals connected to the output. It is suitable for use in a correction device for correcting a signal.
[0002]
[Prior art]
In recent years, with the progress of digital signal processing technology and semiconductor technology, a consumer digital video standard for digitally recording moving picture signals of a standard television system, for example, NTSC system or PAL system, has been proposed. A digital video camera in which a device and an imaging device are integrated has been commercialized. Some of such digital video cameras have a still image recording function by utilizing the feature of digital recording.
[0003]
Further, there is also a digital camera equipped with a digital I / F for connection to a computer or the like, and having a function of taking a captured image into the computer. Further, an apparatus that includes a plurality of recording media and is capable of selecting a recording medium according to the purpose of use of an image has been put to practical use.
[0004]
In such an apparatus, when a recorded image is connected to a television and played back, the image size is determined by the digital video standard, for example, 720 × 480 pixels, and there is no problem. When transferring an image to another medium, a larger number of pixels may be required due to a problem in image quality.
[0005]
With the increase in the number of pixels of the image sensor, it is necessary to drive the image sensor at a higher frequency in order to read information of all pixels of the image sensor. There is a problem that causes an increase in power.
[0006]
Therefore, a method of increasing the data rate of imaging information while keeping the driving frequency of the imaging element low has been considered. As one of such methods, there is a method in which an imaging surface is divided into a plurality of regions, each region has an independent charge transfer unit, an amplifier, and an output terminal, and imaging signals are read out in parallel.
[0007]
FIG. 9 shows an example of an image pickup apparatus using the above image pickup device. In FIG. 9, the imaging surface of the imaging device 900 is divided into left and right two regions. Reference numerals 901 and 902 denote photoelectric conversion and vertical transfer units, 903 and 904 denote horizontal transfer units, 905 and 906 denote amplifiers, and 907 and 908 denote output terminals. The use of the imaging device having such a structure has an advantage that imaging information having a data rate twice as high as the driving frequency of the imaging device can be obtained.
[0008]
On the other hand, a disadvantage of this method is that when an image is generated by combining two regions due to the non-uniformity of the characteristics of the amplifier and the external peripheral circuit in each region, a boundary line occurs due to a level difference between the regions. There is a problem that image quality deteriorates.
[0009]
As a method of reducing the image quality deterioration due to these non-uniformities, there is a method in which a black level and a standard white level of each area are measured in advance to obtain a correction coefficient, and the non-uniformity is corrected by the correction coefficient at the time of imaging. It is considered.
[0010]
FIG. 9 shows a configuration example of such a correction circuit. A subject image formed on the image sensor 900 by an image forming optical system (not shown) is converted into an electric signal by the image sensor 900 and output terminals 907 and 907 are provided in accordance with a drive pulse supplied from a drive timing generating circuit (not shown). 908.
[0011]
The two-system image signals obtained from the image sensor 900 are subjected to analog signal processing by analog signal processing units 909 and 910 and then A / D converted, and supplied to black level correction circuits 911 and 912 and a black level difference detection circuit 913. Is done. The black level difference detection circuit 913 detects a black level difference from the two systems of image signals and calculates a correction coefficient.
[0012]
This correction coefficient is supplied to black level correction circuits 911 and 912, and the difference between the black levels is corrected based on the correction coefficient. The signal of the optical black pixel of the image sensor 900 is used for detecting the difference between the black levels. The detection and the calculation of the correction value are performed only once at a predetermined time, and the obtained correction coefficient is stored in the memory 920, so that the detection is not performed in the subsequent photographing, and the black level is determined by the correction coefficient stored in the memory 920. The difference is corrected.
[0013]
Next, the signals are supplied to white level correction circuits 914 and 915 and a white level difference detection circuit 916. The white level difference detection circuit 914 detects a white level difference from the two systems of image signals and calculates a correction coefficient. The correction coefficient is supplied to black and white level correction circuits 914 and 915, and the difference between the white levels is corrected based on the correction coefficient.
[0014]
For detecting the difference in white level, the image sensor 900 is irradiated with uniform light so as to obtain a standard white level, and an image signal at that time is used. The detection and the calculation of the correction value are performed only once at a predetermined time, and the obtained correction coefficient is stored in the memory 921, so that the detection is not performed in the subsequent photographing and the correction coefficient stored in the memory 921 is used. The correction of the white level difference is performed.
[0015]
The signal subjected to the white level correction is subjected to γ correction processing, contour correction processing, color correction processing and the like in a camera signal processing circuit 918 after the left and right images are synthesized as one image by a screen synthesis circuit 917. , And a luminance signal and a color difference signal from an output terminal 919.
[0016]
[Problems to be solved by the invention]
However, in the above-described conventional example, the correction coefficient is calculated only under predetermined conditions, such as when a standard white image is captured, and thus there is a problem that real-time properties are lacking. For this reason, it is not possible to quickly respond to dynamic fluctuations such as camera shake of the imaging apparatus, and it may not be possible to sufficiently correct non-uniformity between regions.
[0017]
SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has an object to enable real-time correction of non-uniformity among a plurality of imaging regions by quickly responding to dynamic fluctuations such as camera shake of an imaging device. The purpose is to do.
[0018]
[Means for Solving the Problems]
A correction device according to the present invention is a correction device that corrects a plurality of imaging signals from a plurality of output units of an imaging device, wherein a level adjustment unit for adjusting a level of the plurality of imaging signals and the imaging device are provided. Correction coefficient determining means for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on a detection result of a blur amount of the imaging apparatus, wherein the correction coefficient determined by the correction coefficient determining means is The signal is supplied to a level adjusting means so that the level difference between the plurality of imaging signals is reduced.
[0019]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment in which the correction device of the present invention is applied to an imaging device will be described with reference to the accompanying drawings.
(First Embodiment)
FIG. 1 is a diagram schematically showing an embodiment in which the present invention is applied to a single-panel video camera.
In FIG. 1, reference numeral 100 denotes a CCD area sensor in which an imaging area is divided into two, each having an output terminal; 101, a photoelectric conversion unit and a vertical transfer unit; and 103 and 104, a horizontal transfer unit; It is divided into two parts in the horizontal direction.
[0020]
Output amplifiers 105 and 106 amplify signal charges, and 107 and 108 are output terminals for imaging signals. Reference numerals 109 and 110 denote analog front ends for performing correlated double samples and AD conversion. 111 and 112 are black level detecting and correcting means, 113 and 114 are gain adjusting means for adjusting gain, and 115 is a screen synthesizing means for synthesizing two systems of image signals to generate one image.
[0021]
Reference numeral 116 denotes a step evaluation value generating means for detecting non-uniformity between the two systems, 117 a microcomputer for controlling the system, 118 a camera signal processing means, 119 an output terminal, and 120 a rewritable nonvolatile memory. Memory. Reference numeral 121 denotes a camera shake amount detection unit provided in the imaging optical system.
[0022]
The image forming optical system is for forming a subject image on the CCD 100, and the microcomputer 117 controls focus and aperture. A subject image formed on the CCD 100 by the image forming optical system is converted into an electric signal by the photoelectric conversion unit 101, then divided into two systems by horizontal transfer paths 103 and 104, and supplied to output amplifiers 105 and 106. .
In the present embodiment and the embodiments described later, a correction device for detecting and correcting non-uniformity between two systems is configured by the gain adjustment units 113 and 114, the step evaluation value generation unit 116, and the microcomputer 117. are doing.
[0023]
Next, the operation of the video camera of the present embodiment having the above configuration will be described.
A subject image formed on the CCD 100 by an imaging optical system (not shown) is converted into an electric signal by a photoelectric conversion unit 101, then divided into two systems by horizontal transfer paths 103 and 104, and output to output amplifiers 105 and 106. Supplied.
[0024]
The signal charges are amplified to a predetermined level by the output amplifiers 105 and 106, and output from the first output terminal 107 and the second output terminal 108. Hereinafter, the image signal obtained from the first output terminal 107 is referred to as a left channel signal, and the image signal obtained from the second output terminal 108 is referred to as a right channel signal.
[0025]
The left and right imaging signals are subjected to correlated double sampling processing and A / D conversion by analog front ends 109 and 110, and then supplied to black level detection and correction units 111 and 112. The black level detection and correction means 111 and 112 use the dummy signal portion or the optical black signal portion of the image pickup signal so that the black levels of the two systems of image pickup signals coincide with the digital code "0". Correction is performed. Thereby, the error of the offset component between the two systems is removed.
[0026]
The signals whose black levels have been corrected are subjected to gain adjustment by gain adjusting means 113 and 114. The gain applied at the time of gain adjustment is supplied from the microcomputer 117. In the conventional imaging apparatus, the gain of the signal amount in a low illuminance environment is increased by an analog circuit. However, in the imaging apparatus that handles two types of imaging signals as in the present embodiment, the gain adjustment by the analog circuit is performed. Can be a factor of non-uniformity between the two systems. Therefore, in the present embodiment, the gain adjustment is performed by digital operation using the gain adjustment means 113 and 114, thereby eliminating the influence of circuit variation, temporal variation, and temperature variation.
[0027]
In addition, not only gain adjustment for image brightness but also correction of gain error between the two systems is performed here. Generally, the difference in gain between the two systems depends on the magnitude of the output level of the CCD area sensor 100.
[0028]
FIG. 3 is a characteristic diagram showing an example of an output level between two systems and a gain difference between channels. In FIG. 3, the horizontal axis represents the output level of the left channel of the CCD 100, and the vertical axis represents the ratio of the input signal (left channel) of the gain adjustment unit 114 to the signal of the input signal (right channel) of the gain adjustment unit 113, that is, 2 It represents the gain difference of the signal level between the systems.
[0029]
For example, assuming that the left channel output level of the CCD 100 is L0 and the right channel output level is L0right when an image of a subject of a certain brightness is captured, the gain difference E0 at this time is given by the following equation (1).
E0 = L0right / L0 (1)
As shown in this figure, since the relationship between the signal level and the gain difference is not constant, the correction amount of the gain is not a fixed value, and the correction amount needs to be changed according to the gain-up amount.
[0031]
In this embodiment, the reference level Lref is set for the signal after gain adjustment, and the level difference between the two systems is always 0 at the reference level Lref regardless of the gain-up amount, that is, the signal of each channel is set to the reference level Lref. Gain correction is performed so that they match. As the level of the reference level Lref, a gray level of about 75% is selected after the γ correction for the reference white.
[0032]
For example, when the left channel output level of the CCD 100 is L0 and the gain is increased so that the output level of the gain adjustment unit 114 becomes the reference level Lref, the gain A0 given to the left channel gain adjustment unit 114 can be expressed by the following equation. .
A0 = reference level Lref / L0 (2)
Further, at this time, the gain A0right given to the gain adjustment means 113 of the right channel can be expressed by the following equation, where the gain correction amount is C0.
A0right = A0 × C0 (3) and C0 is obtained by the following equation.
C0 = 1.0 / E0 (4)
Similarly, when the output level of the left channel of the CCD 100 is L1, the gain correction amount C1 when the output level of the gain adjustment unit 114 is a gain-up amount that becomes the reference level Lref is obtained by the following equation.
C1 = 1.0 / E1 (5)
FIG. 4 shows a characteristic example of the gain correction amount with respect to the gain increase amount. This correction characteristic differs for each component of the CCD 100 or the analog front ends 109 and 110.
[0036]
Next, measurement of the gain correction characteristic will be described.
The step evaluation value generation means 116 calculates an evaluation value of the screen step based on the pixel values in the rectangular area specified near the boundary of the divided area, and outputs the evaluation value to the microcomputer 117.
[0037]
FIG. 2 shows an example of a rectangular area in the screen. As shown in FIG. 2, rectangular regions 203 and 204 are set near the boundary between the two divided regions 201 and 202, and the pixel values in these regions are used for evaluating a screen step.
[0038]
The CCD 100 has an on-chip color filter attached to a pixel portion in order to capture a color image on a single plate. The on-chip color filters are arranged, for example, as shown at 205 in FIG. The step evaluation value generation means 116 selects a pixel value of one color among them, calculates an average value in the area, and uses this as an evaluation value of the screen step.
[0039]
At the time of measuring the gain correction characteristic, an image of a subject having a uniform brightness is taken, and the microcomputer 117 sets the same gain multiplier to the gain adjustment means 113 and 114 to perform the measurement. The average level of the pixels in one rectangular area 203 is set to the level of the left channel, and the average level of the pixels in the other rectangular area 204 is set to the level of the right channel and output to the microcomputer 117.
[0040]
The microcomputer 117 calculates the gain correction amount of the right channel based on the level of the left channel as described above. By performing such a measurement at predetermined intervals at the output level of the CCD 100, a gain correction characteristic is generated.
[0041]
The microcomputer 117 stores the generated gain correction characteristic in a rewritable non-volatile memory 120 such as an EEPROM (Electrically Erasable Programmable Read Only Memory). The generation of the gain correction characteristic is executed, for example, at the time of factory adjustment. Therefore, it cannot respond to dynamic fluctuations such as temporal fluctuations and temperature fluctuations, and the gain difference remains as an error.
[0042]
Next, correction of the residual gain error at the time of general photographing will be described.
FIG. 5 shows a method of determining a correction coefficient based on a result of detection of a blur amount of a video camera, and applying the determined correction coefficient to a gain adjustment unit to obtain a correction coefficient of each imaging signal output from a different output terminal of the CCD area sensor. This shows a configuration of a block for correcting a residual gain error, which is executed by a microcomputer 117 which is a correction coefficient determining means for performing adjustment so as to reduce the level difference. The signals A, B, C, and D in FIG. 5 correspond to the signals A, B, C, and D in FIG. 1, where reference symbol A denotes a left channel step evaluation value, reference sign B denotes a right channel step evaluation value, Symbol C is a left channel gain adjustment value, and symbol D is a right channel gain adjustment value.
[0043]
The left channel step evaluation value A and the right channel step evaluation value B input to the microcomputer 117 are input to the gain error calculation means 501, and the gain error E is obtained. The gain error E is obtained by the following equation.
E = B / A Expression (6)
The gain error amount E obtained by the gain error calculating means 501 is simply a ratio of pixel levels, and is affected not only by non-uniformity between channels but also by a level difference of the subject itself. Therefore, in order to perform correct gain error correction, it is necessary to eliminate a subject-dependent level difference component. In the present embodiment, the subject-dependent level difference component is eliminated by the limiter unit 502 and the integration unit 503.
[0045]
FIG. 6 shows the input / output characteristics of the limiter unit 502. The origin in FIG. 6 represents a point where limiter input = limiter output = 1.0. Since there is a level ratio between channels, the value when there is no gain error is 1.0.
[0046]
As shown in FIG. 6, when the level difference ratio exceeds the threshold value TH, the limiter output becomes 1.0. The threshold value TH is determined in association with the residual gain error amount. As a result of this processing, a level difference that is large is regarded as a subject-dependent level difference and is eliminated.
[0047]
FIG. 7 shows the internal configuration of the integration means 503. After subtracting the input signal X (0) from the signal Y (-1) delayed by a predetermined time in the subtraction means 702, the coefficient k is multiplied by the coefficient unit 703. The output of the coefficient unit 703 is added to the delay signal by the adding means 704 to become an output, while being supplied to the delay means 705. When the output signal is expressed as Y (0), the following expression is obtained.
Y (0) = kX (0) + (1-k) Y (-1) (0 <k <1) Expression (7)
The delay time is a time equal to the vertical scanning period of the CCD. By this processing, an average value of the error amounts for the past 1 / k frames is obtained. Normally, the subject is not fixed for a long time in the angle of view, so by taking an average over a plurality of frames, the level difference component depending on the subject is canceled out and eliminated.
[0049]
Information on the amount of camera shake is input to the coefficient control unit 701, whereby the coefficient k given to the coefficient unit 703 is controlled. The coefficient control will be described later.
[0050]
Through the above processing, the level difference due to the subject is eliminated, and the gain error due to the non-uniformity between the channels is extracted. Next, the gain error amount is multiplied by a coefficient by the correction amount control unit 504. This coefficient corresponds to the feedback gain of the gain error correction loop. When the gain is large, the correction capability is high, but it becomes unstable against disturbances such as erroneous detection, and when the gain is small, it is stable against disturbances, but the correction capability is low.
[0051]
The output of the correction amount control unit 504 is supplied to a gain correction amount calculation unit 506. The output of the gain correction characteristic table 505 is also supplied to the gain correction amount calculation means 506. The gain correction characteristic table 505 is a table in which the gain correction characteristics described above are tabulated, and as shown in FIG. 4, a gain correction amount is obtained corresponding to the gain increase amount.
[0052]
In the gain correction amount calculating means 506, the gain adjustment value for the right channel is actually calculated by multiplying the two input signals by the gain up amount. Then, the gain adjustment value thus calculated is supplied to the gain adjustment means 113 shown in FIG. The gain increasing amount itself is supplied to the gain adjusting means 114.
[0053]
The signal after the gain adjustment is supplied to the screen synthesizing means 115 and the step evaluation value generating means 116. The screen synthesizing unit 115 synthesizes the two-system signals and outputs the synthesized signal to the camera signal processing circuit 118 and the AF evaluation value generating unit 122 as an image of one screen. The camera signal processing circuit 118 performs signal processing such as γ correction, color correction, and contour correction, and outputs the image signal from a terminal 119.
[0054]
The camera shake amount detection means 121 detects the amount of camera shake which occurs when the user performs hand-held imaging, and the detection result is input to the microcomputer 117. The microcomputer 117 calculates a camera shake correction amount based on the result.
[0055]
The camera shake correction amount is supplied to the camera signal processing circuit 118, and the camera signal processing circuit 118 performs a camera shake correction process. Note that the method of calculating the camera shake correction amount is not essential in the present invention, and a detailed description thereof will be omitted.
[0056]
As described above, when measuring the level difference between the left and right screens from a general captured image, the level difference of the subject itself can be cited as a disturbance element. In other words, when a subject having a level difference is photographed in the rectangular regions 203 and 204, the level difference cannot be distinguished from the step between the regions, and thus erroneous correction may be performed.
[0057]
As described above, time integration is performed to eliminate the cause, but the effect is not obtained in a situation where a stationary object is photographed at a fixed angle of view. In order to cope with such a situation, in the present embodiment, variable control of the characteristics of the correction loop is performed according to the camera shake amount (camera shake amount).
[0058]
FIG. 8 shows the characteristics of the coefficient control for the camera shake amount, and shows the operation of the coefficient control unit 701 in FIG. In FIG. 8, the horizontal axis represents the camera shake amount, and the camera shake amount increases toward the right. The vertical axis represents the output coefficient. As shown in FIG. 8, the output coefficient in the state without blur has a characteristic that the coefficient value increases as the blur amount increases.
[0059]
When the amount of blur is large, the positional relationship between the rectangular area and the subject is considered to fluctuate greatly. In such a situation, even if the number of frames to be averaged is small, it is considered that the level difference of the subject factor can be sufficiently eliminated. Conversely, in a situation where the amount of blur is small or there is no blur, the subject is more susceptible to the level difference due to the subject factor. Is controlled so as to be stable.
[0060]
Furthermore, when no blur is detected and the imaging device is considered to be fixed to a tripod or the like, an operation may be considered in which the coefficient k is set to 0 and the evaluation value of the level difference is not used.
[0061]
(Another embodiment of the present invention)
The present invention may be applied to a system including a plurality of devices or an apparatus including one device.
[0062]
Further, a transmission medium such as the Internet or the like is transmitted to a computer in an apparatus or a system connected to the various devices so as to operate various devices so as to realize the functions of the above-described embodiments. Also, the present invention provides a program code of software for realizing the functions of the above-described embodiment through the above-described embodiment, and executes the above-described various devices according to a program stored in a computer (CPU or MPU) of the system or the apparatus. Are included in the scope of the present invention.
[0063]
In this case, the program code itself of the software implements the functions of the above-described embodiment, and the program code itself and a unit for supplying the program code to the computer, for example, the program code is stored. The storage medium described constitutes the present invention. As a storage medium for storing such a program code, for example, a flexible disk, a hard disk, an optical disk, a magneto-optical disk, a CD-ROM, a magnetic tape, a nonvolatile memory card, a ROM, and the like can be used.
[0064]
When the computer executes the supplied program code, not only the functions described in the above-described embodiments are realized, but also the OS (Operating System) running on the computer or another program. It goes without saying that such a program code is also included in the embodiment of the present invention when the functions described in the above embodiment are realized in cooperation with application software or the like.
[0065]
Further, after the supplied program code is stored in a memory provided in a function expansion board of a computer or a function expansion unit connected to the computer, a CPU provided in the function expansion board or the function expansion unit based on the instruction of the program code. The present invention also includes a case in which the functions of the above-described embodiments are implemented by performing some or all of the actual processing.
[0066]
Examples of embodiments of the present invention will be described below.
[Embodiment 1] A correction device for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
Level adjustment means for adjusting the level of the plurality of imaging signals, and a correction coefficient determination means for determining a correction coefficient for reducing the level difference between the plurality of imaging signals,
The correction coefficient determination means corrects the subject-dependent level difference component to determine the correction coefficient, and adjusts the determined correction coefficient to the level adjustment means so as to reduce the level difference between the imaging signals. A correcting device.
[Embodiment 2] An output level detection unit that detects output levels of the plurality of imaging signals,
The correction apparatus according to claim 1, wherein the correction coefficient determination unit determines a correction coefficient based on the level detection result so as to reduce a level difference between the plurality of imaging signals.
[0067]
[Embodiment 3] The output level detecting means includes an area selecting means for selecting a predetermined area from among the plurality of imaging signals, and an average for calculating an average level in the area selected by the area selecting means. The correction device according to the second embodiment, further comprising a level calculation unit.
[0068]
[Embodiment 4] The output level detection unit includes a color signal selection unit that selects a predetermined color signal from among the plurality of imaging signals, and a detection result is obtained by using the color signal selected by the color signal selection unit. The correction device according to the second or third embodiment, wherein the correction device generates
[0069]
[Embodiment 5] The correction coefficient determining unit calculates a gain error between the plurality of imaging signals from among a plurality of detection results output from the output level detecting unit, and the plurality of imaging units. Threshold setting means for setting a threshold for eliminating a subject-dependent level difference component in the signal; and when a signal calculated by the gain error calculation means is input, a gain error between the plurality of imaging signals is reduced. A non-linear processing unit that outputs a predetermined reference value when the threshold value set by the threshold setting is exceeded, and outputs the input gain error as it is when the threshold value is not exceeded,
The correction apparatus according to any one of embodiments 2 to 4, wherein a correction coefficient is determined based on an output signal of the non-linear processing unit.
[0070]
[Embodiment 6] The correction coefficient determination unit includes an evaluation value generation unit configured to generate an evaluation value from a detection result of the output level detection unit, and an evaluation value generated by the evaluation value generation unit averaged over a plurality of frames. Averaging means, and a frame number control means for setting the number of frames to be averaged by the averaging means,
The correction apparatus according to any one of embodiments 2 to 5, wherein the correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number control unit.
[0071]
[Seventh Embodiment] The correction apparatus according to the sixth embodiment, further comprising a frame number control unit that variably controls the number of frames to be averaged by the averaging unit in accordance with a shake amount of the correction device.
[0072]
Embodiment 8 A correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging device,
Level adjustment processing for adjusting the levels of the plurality of imaging signals, and a correction coefficient determination processing for determining a correction coefficient for reducing the level difference between the plurality of imaging signals,
The correction coefficient determination processing determines the correction coefficient by correcting a subject-dependent level difference component, and adjusts the determined correction coefficient to the level adjustment processing so as to reduce the level difference of each imaging signal. Correction method.
[Embodiment 9] An output level detection process for detecting output levels of the plurality of imaging signals,
The correction method according to claim 8, wherein the correction coefficient determination processing determines a correction coefficient based on the level detection result such that a level difference between the plurality of imaging signals is reduced.
[0073]
[Embodiment 10] The output level detection processing includes an area selection processing for selecting a predetermined area among the plurality of imaging signals, and an average for calculating an average level in the area selected by the area selection processing. The correction method according to the ninth embodiment, further comprising a level calculation process.
[0074]
[Embodiment 11] The output level detection process includes a color signal selection process of selecting a predetermined color signal from the plurality of imaging signals, and the output level detection process is performed using the color signal selected by the color signal selection process. The correction method according to embodiment 9 or 10, wherein a result is generated.
[0075]
[Embodiment 12] The correction coefficient determination process includes a gain error calculation process of calculating a gain error between the plurality of imaging signals from a plurality of detection results output from the output level detection process; A threshold setting process for setting a threshold for eliminating a subject-dependent level difference component in the signal, and when a signal calculated by the gain error calculation process is input, a gain error between the plurality of imaging signals is reduced. Non-linear processing that outputs a predetermined reference value when the threshold value set by the threshold setting is exceeded, and outputs the input gain error as it is when the threshold value is not exceeded,
The correction method according to any one of embodiments 9 to 11, wherein a correction coefficient is determined based on an output signal of the non-linear processing.
[0076]
[Thirteenth Embodiment] The correction coefficient determination process includes an evaluation value generation process of generating an evaluation value from a detection result of the output level detection process, and an evaluation value generated by the evaluation value generation process averaged over a plurality of frames. Averaging process, and a frame number control process of setting the number of frames to be averaged by the averaging process,
The correction method according to any one of embodiments 9 to 12, wherein the correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number control process.
[0077]
[Embodiment 14] The correction method according to embodiment 13, further comprising a frame number control process of variably controlling the number of frames to be averaged in the averaging process according to a blur amount of the correction method.
[0078]
[Embodiment 15] A program for causing a computer to execute a correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
Level adjustment processing for adjusting the levels of the plurality of imaging signals, and a correction coefficient determination processing for determining a correction coefficient for reducing the level difference between the plurality of imaging signals,
The correction coefficient determination processing determines the correction coefficient by correcting a subject-dependent level difference component, and adjusts the determined correction coefficient to the level adjustment processing so as to reduce the level difference of each imaging signal. Computer program for causing a computer to perform the following.
[0079]
[Embodiment 16] A computer-readable recording medium on which the computer program according to Embodiment 15 is recorded.
[0080]
【The invention's effect】
As described above, according to the present invention, a correction coefficient such that the levels of a plurality of imaging signals are equal is determined based on a blur amount detection result, and the plurality of imaging signals are determined using the determined correction coefficient. Since the adjustment for reducing the level difference is performed, the non-uniformity between the plurality of imaging regions can be corrected in real time.
According to another feature of the present invention, adaptive control is performed in accordance with the amount of shake of the imaging apparatus, so that a subject-dependent level difference component can be effectively removed, and dynamic Even when a change occurs, a step that appears in an image can be eliminated.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention and showing a configuration of a first embodiment of a video camera to which a correction device of the present invention is applied.
FIG. 2 is a diagram illustrating a rectangular area at a boundary of a divided screen.
FIG. 3 is a characteristic diagram showing a CCD output level and a gain difference between channels.
FIG. 4 is a diagram showing a gain correction characteristic with respect to a gain-up amount.
FIG. 5 is a block diagram illustrating a configuration example of a unit that executes a procedure of calculating a gain adjustment value according to the first embodiment.
FIG. 6 is a diagram illustrating input / output characteristics of a limiter according to the first embodiment.
FIG. 7 is a block diagram illustrating a configuration example of an integration unit according to the first embodiment.
FIG. 8 is a characteristic diagram showing a coefficient control characteristic of an integrating means according to the first embodiment.
FIG. 9 is a block diagram illustrating an example of a conventional imaging apparatus.
[Explanation of symbols]
Reference Signs List 100 CCD area sensor 101 Photoelectric conversion unit and vertical transfer unit 103, 104 Horizontal transfer unit 105, 106 Output amplifier 107, 108 Image signal output terminal 109, 110 Analog front end 111, 112 Black level detection and correction means 113, 114 Gain adjusting means 115 screen synthesizing means 116 step evaluation value generating means 117 microcomputer for controlling the system 118 camera signal processing means 119 output terminal 120 rewritable nonvolatile memory 121 camera shake amount detecting means

Claims (1)

A correction device for correcting a plurality of imaging signals from a plurality of output units of the imaging device,
Level adjustment means for adjusting the levels of the plurality of imaging signals, and a correction coefficient for reducing a level difference between the plurality of imaging signals based on a detection result of a blur amount of an imaging device including the imaging element. Correction coefficient determining means for performing
A correction device, wherein the correction coefficient determined by the correction coefficient determination means is supplied to the level adjustment means so as to perform adjustment so as to reduce the level difference between the plurality of imaging signals.

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