JP4136776B2 - Correction apparatus, imaging apparatus, correction method, computer-readable storage medium, and program - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
  The present invention relates to a correction apparatus, an imaging apparatus, a correction method, a computer-readable storage medium, and a program, and in particular, an imaging surface is divided into a plurality of parts and an amplifier that amplifies an imaging signal of each area and is connected to this output The present invention is suitable for use in a correction device that corrects a signal from a solid-state imaging device having a plurality of imaging signal output terminals.
[0002]
[Prior art]
In recent years, due to advances in digital signal processing technology and semiconductor technology, consumer digital video standards for digital recording of standard television, for example, NTSC and PAL video signals, have been proposed. Digital video cameras in which a device and an imaging device are integrated have been commercialized. Some digital video cameras have a still image recording function by taking advantage of the feature of digital recording.
[0003]
Some have a digital I / F for connecting to a computer or the like, and have a function of taking a captured image into the computer. Furthermore, an apparatus that includes a plurality of recording media and that can select a recording medium according to the purpose of use of an image has been put into practical use.
[0004]
In such a device, when a recorded image is reproduced by connecting to a television, the image size is determined by the digital video standard, for example, 720 × 480 pixels, but there is no problem, but via a digital I / F When transferring an image to other media, a larger number of pixels may be required due to image quality problems.
[0005]
Accompanying the increase in the number of pixels in an image sensor, it is necessary to drive the image sensor at a higher frequency in order to read out information on all pixels of the image sensor. There was a problem that caused an increase in electric power.
[0006]
Therefore, a method of increasing the data rate of imaging information while keeping the driving frequency of the imaging element low is considered. As one of such methods, there is a method in which the imaging surface is divided into a plurality of regions, and independent charge transfer units, amplifiers, and output terminals are provided in the respective regions, and the imaging signals are read out in parallel.
[0007]
FIG. 14 shows an example of an imaging apparatus using the imaging element as described above. In FIG. 14, the imaging surface of the imaging device 1400 is divided into two regions on the left and right. 1401 and 1402 are photoelectric conversion and vertical transfer units, 1403 and 1404 are horizontal transfer units, 1405 and 1406 are amplifiers, and 1407 and 1408 are output terminals. By using the imaging device having such a structure, there is 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, as a disadvantage of this method, due to non-uniformity of the characteristics of the amplifier and external peripheral circuit in each area, when an image is generated by combining two areas, a boundary line is generated due to a level difference between the areas. There was a problem that image quality deteriorated.
[0009]
As a method of reducing the image quality degradation due to these non-uniformities, there is a method in which the correction coefficient is obtained by measuring the black level and the standard white level of each area in advance, and the non-uniformity is corrected by this correction coefficient during imaging. It is considered.
[0010]
FIG. 14 shows a configuration example of such a correction circuit. A subject image formed on the image sensor 1400 by an imaging optical system (not shown) is converted into an electrical signal by the image sensor 1400, and an output terminal 1407 and an output terminal 1407 according to a drive pulse supplied from a drive timing generation circuit (not shown). 1408 is output.
[0011]
The two systems of image signals obtained from the image sensor 1400 are subjected to analog signal processing by the analog signal processing units 1409 and 1410 and then AD-converted and supplied to the black level correction circuits 1411 and 1412 and the black level difference detection circuit 1413. Is done. The black level difference detection circuit 1413 detects a black level difference from two systems of image signals and calculates a correction coefficient.
[0012]
This correction coefficient is supplied to black level correction circuits 1411 and 1412, and the black level difference is corrected based on the correction coefficient. For detection of the black level difference, a signal of an optical black pixel of the image sensor 1400 is used. The detection and the correction value calculation are performed only once at a predetermined time, and the obtained correction coefficient is stored in the memory 1420, so that the black level is determined by the correction coefficient stored in the memory 1420 without performing detection at the subsequent photographing. Difference correction is performed.
[0013]
Next, each signal is supplied to white level correction circuits 1414 and 1415 and a white level difference detection circuit 1416. The white level difference detection circuit 1414 detects a difference in white level from two types of image signals and calculates a correction coefficient. This correction coefficient is supplied to black and white level correction circuits 1414 and 1415, and the difference in white level is corrected based on the correction coefficient.
[0014]
To detect the difference in white level, the image sensor 1400 is irradiated with uniform light that provides a standard white level, and the image signal at that time is used. The detection and the correction value calculation are performed only once at a predetermined time, and the obtained correction coefficient is stored in the memory 1421, so that the detection is not performed at the time of subsequent photographing and the correction coefficient stored in the memory 1421 is used. White level difference correction is performed.
[0015]
The white level corrected signal is subjected to γ correction processing, contour correction processing, color correction processing, and the like by the camera signal processing circuit 1418 after the left and right images are combined as a single image by the screen combining circuit 1417. The luminance signal and the color difference signal are output from the output terminal 1419.
[0016]
[Problems to be solved by the invention]
However, in the above conventional example, since the correction coefficient is calculated only under a predetermined condition such as capturing a standard white image, there is a problem that the real-time property is lacking. For this reason, dynamic fluctuations such as temperature fluctuations or fluctuations with time cannot be dealt with, and unevenness between regions may not be sufficiently corrected.
[0017]
The present invention has been made in view of the above-described problems, and is capable of correcting inhomogeneities between a plurality of imaging regions in real time in consideration of temperature fluctuations in the imaging element or in the vicinity of the imaging element. Objective.
[0018]
[Means for Solving the Problems]
  The correction device of the present invention is a correction device that corrects a plurality of imaging signals from a plurality of output units of an imaging device, and includes a level adjustment unit for adjusting the levels of the plurality of imaging signals, Output level detecting means for detecting a level, and correction coefficient determining means for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information, wherein the correction coefficient determining means includes the output Evaluation value generation means for generating an evaluation value from the detection result of the level detection means, evaluation value averaging means for averaging the evaluation values generated by the evaluation value generation means between a plurality of frames, and the evaluation value averaging means The number of frames is set from the frame number setting means for setting the number of frames to be averaged and an evaluation value obtained by averaging the number of frames set by the frame number setting means. Gain error calculating means for calculating a gain error between signals, threshold setting means for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals, and gain calculated by the gain error calculating means When an error is input, if a gain error between the imaging signals exceeds a threshold set by the threshold setting means, a predetermined reference value is output, and if the gain error does not exceed the threshold Comprises a non-linear processing means for outputting the input gain error as it is, and the correction coefficient determining means determines the correction coefficient based on a signal output from the non-linear processing means, and is determined by the correction coefficient determining means. In order to apply the corrected coefficient to the level adjusting unit and perform adjustment so that the level difference between the plurality of imaging signals is reduced, the evaluation value averaging unit The number of frames to perform averaging had, and further comprising a frame number control means for controlling in response to the image sensor or the temperature around the image pickup device.
  Another feature of the correction apparatus according to the present invention is a correction apparatus that corrects a plurality of imaging signals from a plurality of output units of the imaging element, and adjusts the levels of the plurality of imaging signals. Level adjustment means, output level detection means for detecting the level of the imaging signal, and correction coefficient determination means for determining a correction coefficient for reducing the level difference between the plurality of imaging signals based on temperature information, The correction coefficient determination means includes a step evaluation value generation means for generating an evaluation value from the detection result of the output level detection means, and a gain between the plurality of imaging signals based on the evaluation value generated by the step evaluation value generation means. A gain error calculating means for calculating an error; a threshold setting means for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals; and the gain error calculating means. When the gain error calculated by the above is input, if the gain error between the imaging signals exceeds the threshold set by the threshold setting means, a predetermined reference value is output, and the gain error is the threshold The non-linear processing means that outputs the input gain error as it is, the gain means that multiplies the signal output from the non-linear processing means, and the gain that the gain means applies to the signal. Gain control means for controlling according to the temperature of the element or the surroundings of the image sensor, wherein the correction coefficient determining means determines the correction coefficient based on a signal multiplied by the gain means, and determines the correction coefficient The correction coefficient determined by the means is applied to the level adjusting means to perform adjustment so that the level difference between the plurality of imaging signals is reduced. To.
  The correction method of the present invention is a correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging device, and includes a level adjustment step for adjusting the levels of the plurality of imaging signals, An output level detecting step for detecting a level; and a correction coefficient determining step for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information, wherein the correction coefficient determining step includes the output An evaluation value generation step for generating an evaluation value from the detection result in the level detection step, an evaluation value averaging step for averaging the evaluation values generated in the evaluation value generation step among a plurality of frames, and the evaluation value averaging step From the frame number setting step for setting the number of frames to be averaged in the above, and the evaluation value obtained by averaging the number of frames set in the frame number setting step, A gain error calculating step for calculating a gain error between a plurality of imaging signals, a threshold setting step for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals, and a gain error calculating step. If the gain error between the imaging signals exceeds the threshold value set in the threshold value setting step when the gain error is input, a predetermined reference value is output, and the gain error exceeds the threshold value. A non-linear processing step that outputs the input gain error as it is, the correction coefficient determining step determines the correction coefficient based on the signal output in the non-linear processing step, and determines the correction coefficient In order to provide the correction coefficient determined in the step to the level adjustment step and perform adjustment so that the level difference between the plurality of imaging signals is reduced, The number of frames to perform averaging in the evaluation value averaging process, and further comprising a frame number control step of controlling according to the image sensor or the temperature around the image pickup device.
  Another feature of the correction method of the present invention is a correction method for correcting a plurality of image pickup signals from a plurality of output units of an image pickup device for adjusting the levels of the plurality of image pickup signals. A level adjustment step, an output level detection step for detecting the level of the imaging signal, and a correction coefficient determination step for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information, The correction coefficient determining step includes a step evaluation value generating step for generating an evaluation value from a detection result in the output level detecting step, and a gain between the plurality of imaging signals from the evaluation value generated in the step evaluation value generating step. A gain error calculating step for calculating an error, a threshold setting step for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals, and the gain error When the gain error calculated in the output step is input, if the gain error between the imaging signals exceeds the threshold set in the threshold setting step, a predetermined reference value is output, and the gain error is If the threshold value is not exceeded, a non-linear processing step that outputs the input gain error as it is, a gain step that multiplies the signal output in the non-linear processing step, and a gain that is applied to the signal in the gain step, A gain control step for controlling the image pickup device or a temperature around the image pickup device, and the correction coefficient determination step determines the correction coefficient based on the signal multiplied by the gain in the gain step, and the correction The correction coefficient determined in the coefficient determination step is given to the level adjustment step, so that the level difference between the plurality of imaging signals is reduced. And performing adjustment.
[0019]
DETAILED DESCRIPTION OF THE INVENTION
Next, an embodiment in which the correction apparatus of the present invention is applied to an imaging apparatus 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, 100 is a CCD area sensor having an imaging region divided into two and each having an output terminal, 101 is a photoelectric conversion unit and vertical transfer unit, and 103 and 104 are horizontal transfer units, with the center of the screen as a boundary. It is divided into two in the left-right direction.
[0020]
  Reference numerals 105 and 106 denote output amplifiers that amplify the signal charge, and 107 and 108 denote output terminals for the imaging signal.(Output part)It is. Reference numerals 109 and 110 denote analog front ends that perform AD conversion with the correlated double samples. Reference numerals 111 and 112 denote black level detection and correction means; 113 and 114, gain adjustment means for adjusting gain; and 115, screen composition means for synthesizing two image signals to generate one image.The black level detection and correction means 111 and 112 and the gain adjustment means 113 and 114 function as level adjustment means for adjusting the level of the imaging signal.
[0021]
116 is a step evaluation value generating means for detecting non-uniformity between the two systems, 117 is a microcomputer for controlling the system, 118 is a camera signal processing means, 119 is an output terminal, and 120 is a rewritable nonvolatile memory. It is memory. A thermometer 121 measures the temperature of the CCD 100.
In the present embodiment and later-described embodiments, a gain adjusting unit 113, 114, a step evaluation value generating unit 116, and a microcomputer 117 constitute a correction device for detecting and correcting nonuniformity between two systems. is doing.
[0022]
  next,in frontThe operation of the video camera of the present embodiment in the above configuration will be described.
  An object image formed on the CCD 100 by an imaging optical system (not shown) is converted into an electric signal by the photoelectric conversion unit 101 and then transferred horizontally.PartDivided into two systems by 103 and 104 and supplied to output amplifiers 105 and 106.
[0023]
The signal charge is 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, an imaging signal obtained from the first output terminal 107 is referred to as a left channel signal, and an imaging signal obtained from the second output terminal 108 is referred to as a right channel signal.
[0024]
The left and right two-line imaging signals are subjected to correlated double sample processing and AD conversion by the analog front ends 109 and 110, and then supplied to the black level detection and correction means 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 level of the two systems of the image pickup signal coincides with “0” of the digital code. Correction is performed. As a result, the error of the offset component between the two systems is removed.
[0025]
The signal whose black level is corrected is subjected to gain adjustment by the 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 illumination environment is increased by an analog circuit. However, in the imaging apparatus that handles two systems of imaging signals as in the present embodiment, the gain adjustment by the analog circuit is performed. Can cause non-uniformity between the two systems. Therefore, in the present embodiment, gain adjustment is performed by digital calculation using the gain adjusting means 113 and 114, thereby eliminating the influence of circuit variations, temporal variations, and temperature variations.
[0026]
Further, not only gain adjustment for image brightness but also correction of gain error between the two systems is performed here. In general, the gain difference between the two systems depends on the output level of the CCD area sensor 100.
[0027]
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 is the left channel output level of the CCD 100, and the vertical axis is the ratio of the input signal (left channel) of the gain adjusting means 114 to the input signal (right channel) of the gain adjusting means 113, that is, 2 The signal level gain difference between systems is shown.
[0028]
For example, assuming that the left channel output level of the CCD 100 when an object of a certain brightness is imaged is L0 and the right channel output level is L0right, the gain difference E0 at this time is given by the following equation (1).
E0 = L0right / L0 (1) formula
[0029]
As shown in this figure, since the relationship between the signal level and the gain difference is not constant, the gain correction amount is not a fixed value, and it is necessary to vary the correction amount according to the gain increase amount.
[0030]
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 increase 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 reference level Lref, a gray level of about 75% is selected after the γ correction with respect to the reference white.
[0031]
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 adjusting unit 114 becomes the reference level Lref, the gain A0 given to the left channel gain adjusting unit 114 can be expressed by the following equation. .
A0 = reference level Lref / L0 (2)
[0032]
Further, the gain A0right given to the gain adjusting unit 113 of the right channel at this time can be expressed by the following equation, with the gain correction amount being C0.
A0right = A0 x C0 (3)
And C0 is calculated | required by following Formula.
C0 = 1.0 / E0 (4) formula
[0033]
Similarly, when the left channel output level of the CCD 100 is L1, the gain correction amount C1 when the gain increase amount is such that the output level of the gain adjusting means 114 becomes the reference level Lref is obtained by the following equation.
C1 = 1.0 / E1 (5)
[0034]
FIG. 4 shows a characteristic example of the gain correction amount with respect to the gain increase amount. This correction characteristic is different for each component of the CCD 100 or the analog front ends 109 and 110.
[0035]
  Next, measurement of gain correction characteristics will be described.
  The step evaluation value generation means 116Functions as output level detection means, as will be described later in FIG.Within the specified rectangular area near the boundary of the divided areaFramePixel valueDetect and its detected resultThe evaluation value of the screen level difference is calculated based on the above and output to the microcomputer 117.
[0036]
  FIG. 2 shows an example of a rectangular area in the screen. As shown in FIG. 2, rectangular areas 203 and 204 are arranged in the vicinity of the boundary between the divided areas 201 and 202.I.e. number of framesIs setThe This setting is set by a frame number setting means (not shown). AndPixel values in this area are used for evaluation of the screen level difference.
[0037]
  In the CCD 100, an on-chip color filter is attached to the pixel portion in order to capture a color image with a single plate.in frontThe on-chip color filter has an arrangement as shown by 205 in FIG. The step evaluation value generation means 116 selects a pixel value of one of these colors,Generate an evaluation value,In the areaAverage the evaluation valuesThe average value is calculated, and this is used as the evaluation value of the screen level difference.
[0038]
When measuring the gain correction characteristic, a subject with uniform brightness is imaged, and the microcomputer 117 sets the same gain multiplier to the gain adjusting means 113 and 114. The average level of the pixels in one rectangular area 203 is set to the left channel level, and the average level of the pixels in the other rectangular area 204 is set to the right channel level and output to the microcomputer 117.
[0039]
The microcomputer 117 calculates the gain correction amount of the right channel as described above with reference to the level of the left channel. Such a measurement is performed at predetermined intervals at the output level of the CCD 100, thereby generating a gain correction characteristic.
[0040]
The microcomputer 117 stores the generated gain correction characteristic in a rewritable nonvolatile memory 120 such as an EEPROM (Electrically Erasable Programmable Read Only Memory). The generation of the gain correction characteristic is executed at the time of factory adjustment, for example. Therefore, the gain difference remains as an error without being able to cope with dynamic fluctuations such as aging fluctuations and temperature fluctuations.
[0041]
Next, correction of the residual gain error during general imaging will be described.
FIG. 5 shows correction coefficient determining means for determining a correction coefficient for reducing the level difference between a plurality of imaging signals from a plurality of output terminals of the CCD area sensor based on temperature information obtained by measurement of the thermometer 121. It shows the configuration of a block for correcting a residual gain error executed by a certain microcomputer 117. Signals A, B, C, and D in FIG. 5 correspond to signals A, B, C, and D in FIG. 1, where symbol A is a left channel step evaluation value, symbol B is a right channel step evaluation value, Symbol C is a gain adjustment value for the left channel, and symbol D is a gain adjustment value for the right channel.
[0042]
  The left channel step evaluation value A and the right channel step evaluation value B input to the microcomputer 117 are gain errors.CalculationThe gain error amount E is obtained by inputting to the means 501. The gain error amount E is obtained by the following equation.
E = B / A (6)
[0043]
  Gain errorCalculationThe gain error amount E obtained by the means 501 is simply a ratio of pixel levels, and is affected not only by the non-uniformity between channels but also by the level difference of the subject itself. Therefore, in order to correct the gain error correctly, it is necessary to eliminate the subject-dependent level difference component. In this embodiment, the subject-dependent level difference component is used as a limiter means.(Threshold setting means and nonlinear processing means)502 and the integration means 503 are excluded.
[0044]
  Limiter means(Nonlinear processing means)An example of the input / output characteristics 502 is shown in FIG. The origin of FIG. 6 represents a point where limiter input = limiter output = 1.0. Since the ratio is the level between channels, the value when there is no gain error is 1.0.
[0045]
  As shown in FIG. 6, the ratio of the level differences is the threshold TH.SuperThe limiter output is 1.0. The threshold TH is associated with the residual gain error amount.By the threshold setting means described aboveIt is determined. By this processing, those having a large level difference are regarded as subject-dependent level differences and are eliminated.
[0046]
FIG. 7 shows the internal configuration of the integrating means 503. The input signal X (0) is compared with the signal Y (−1) delayed by a predetermined time in the subtracting means 701, and then multiplied by a coefficient k in a coefficient unit 702. The output of the coefficient unit 702 is added to the delay signal by the adding means 703 and becomes an output while being supplied to the delay means 704. The output signal is expressed as an equation as Y (0) as follows.
Y (0) = kX (0) + (1-k) Y (-1) (0 <k <1) (7)
[0047]
The delay time is equal to the CCD vertical scanning period. By this process, an average value of 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, and by taking an average of a plurality of frames, the subject-dependent level difference component is canceled and eliminated.
[0048]
  Through the processing as described above, a level difference due to a subject is eliminated, and a gain error caused by non-uniformity between channels is extracted. The amount of gain error is the next correction amount control means.(Gain means and gain control means)At 504, the coefficient is multiplied. This coefficient corresponds to the feedback gain of the gain error correction loop. When the gain is large, the correction capability is high, but becomes unstable against disturbance such as false detection, and when the gain is small, it is stable against disturbance, but the correction capability is low.
[0049]
  FIG. 8 shows feedback gain control characteristics with respect to the temperature of the CCD 100. The temperature of the CCD 100 is measured by the thermometer 121 shown in FIG. Tref shown in FIG. 8 is a reference temperature and corresponds to a temperature at the time of measuring the gain correction characteristic. Correction amount control means504As shown in FIG. 8, control is performed such that the feedback gain increases as the temperature deviates from the reference temperature.
[0050]
The main factor of the dynamic fluctuation of the non-uniformity between channels is the temperature fluctuation. By performing such control, it is possible to effectively correct the temperature fluctuation.
[0051]
The output of the correction amount control means 504 is supplied to the gain correction amount calculation means 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 of the gain correction characteristics already described.
[0052]
As illustrated in FIG. 4, a gain correction amount can be obtained corresponding to the gain increase amount. In the gain correction amount calculation means 506, the gain adjustment value for the right channel is actually calculated by multiplying these two input signals and the gain increase amount. Then, the gain adjustment value calculated in this way is supplied to the gain adjustment means 113 shown in FIG. The gain adjustment unit 114 is supplied with the gain increase amount itself.
[0053]
The signal after gain adjustment is supplied to the screen composition unit 115 and the step evaluation value generation unit 116. The screen synthesizing unit 115 synthesizes two systems of signals and outputs them to the camera signal processing circuit 118 as one screen image. The camera signal processing circuit 118 performs signal processing such as γ correction, color correction, and contour correction, and outputs the image signal from the terminal 119.
[0054]
(Second Embodiment)
FIG. 9 is a signal processing block diagram for explaining the second embodiment of the present invention. The specific configuration of the entire imaging apparatus is the same as that of the first embodiment described above. The signal processing in the configuration shown in FIG. 9 is executed in the microcomputer 117 in FIG. The rectangular area for evaluation value measurement is the same as that in the first embodiment.
[0055]
  The left channel step evaluation value A and the right channel step evaluation value B input to the microcomputer 117 are gain errors.CalculationInput to the means 901 to obtain the gain error amount. Gain errorCalculationThe configuration and operation of the means 901 and the limiter means 902 are the same.1Since this is the same as the embodiment of FIG.
[0056]
The output of the limiter unit 902 is input to the integrating unit 903. The temperature around the CCD measured by the thermometer 121 is also input to the integrating means 903 at the same time. The internal configuration of the integrating means 903 is shown in FIG. Operations other than the coefficient control means 1001 are the same as those in the first embodiment.
[0057]
  FIG. 11 shows coefficient control means.(Frame number control means)A coefficient control characteristic of 1001 is shown. In FIG. 11, the horizontal axis represents the temperature around the CCD measured by the thermometer 121, and the vertical axis represents the coefficient supplied to the coefficient unit 1003. Tref described in the graph indicates the reference temperature described in the first embodiment.
[0058]
As shown in the figure, when the CCD ambient temperature is the reference temperature, the output coefficient is a predetermined value k, but when the temperature is outside that temperature, a value larger than k is output. By performing such coefficient control, it is possible to control the response of the correction loop according to the temperature, and it is possible to accurately correct the temperature fluctuation.
[0059]
The output of the integration means 903 is then multiplied by a coefficient in the correction amount control means 904. Unlike the first embodiment, the correction amount control means 904 does not perform temperature control. The operations of the gain correction characteristic table 905 and the gain correction amount calculation unit 906 are the same as those in the first embodiment.
[0060]
Returning to FIG. 1, the obtained left channel gain adjustment value C and right channel gain adjustment value D are supplied to gain adjustment means 114 and 113, respectively.
[0061]
(Third embodiment)
FIG. 12 is a signal processing block diagram for explaining the third embodiment of the present invention. The specific configuration of the entire imaging apparatus is the same as that of the first embodiment. The signal processing shown in FIG. 12 is executed in the microcomputer 117 in FIG. The rectangular area for evaluation value measurement is the same as that in the first embodiment.
[0062]
  The left channel step evaluation value A and the right channel step evaluation value B input to the microcomputer 117 are gain errors.CalculationInput to the means 1201 to obtain the gain error amount. Gain errorCalculationSince the configuration and operation of the means 1201 are the same as those in the first embodiment, description thereof will be omitted.
[0063]
  Gain errorCalculationThe means 1201 is input to the limiter means 1202. The temperature around the CCD measured by the thermometer 121 is also inputted to the limiter means 1202 at the same time.
[0064]
FIG. 13 shows threshold control characteristics in the limiter means 1202. In FIG. 13, the horizontal axis represents the temperature around the CCD measured by the thermometer 121, and the vertical axis represents the limiter threshold. The limiter operation for the threshold value is as shown in FIG. Tref described in the graph indicates the reference temperature described in the first embodiment.
[0065]
As shown in FIG. 13, when the CCD ambient temperature is the reference temperature, the output threshold value is a predetermined value TH, but when the temperature is outside that temperature, a value greater than the predetermined value TH is output. By performing such threshold control, level detection for level difference detection according to temperature becomes possible, and correction for temperature fluctuation can be performed with high accuracy.
[0066]
The output of the limiter 1202 is then input to the integrator 1203. The operation of the integrating means is the same as in the first embodiment. The output of the integrator 1203 is multiplied by a coefficient by the correction amount control means 1204. Unlike the first embodiment, the correction amount control unit 1204 does not perform temperature control.
The operations of the gain correction characteristic table 1205 and the gain correction amount calculation unit 1206 are the same as those in the first embodiment.
[0067]
Returning to FIG. 1, the obtained left channel gain adjustment value C and right channel gain adjustment value D are supplied to gain adjustment means 114 and 113, respectively.
[0068]
(Another embodiment of the present invention)
The present invention may be applied to a system composed of a plurality of devices or an apparatus composed of a single device.
[0069]
Further, in order to operate various devices so as to realize the functions of the above-described embodiments, a transmission medium such as the Internet is transmitted from a storage medium to an apparatus connected to the various devices or a computer in the system. The program implemented by operating the various devices according to the program stored in the computer (CPU or MPU) of the system or apparatus is supplied via the software program code for realizing the functions of the above-described embodiments Are included in the scope of the present invention.
[0070]
In this case, the program code of the software itself realizes the functions of the above-described embodiments, and the program code itself and means for supplying the program code to the computer, for example, the program code are stored. This storage medium constitutes the present invention. As a storage medium for storing the 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, or the like can be used.
[0071]
Further, by executing the program code supplied by the computer, not only the functions described in the above-described embodiments are realized, but also the OS (operating system) or other operating system in which the program code is running on the computer. It goes without saying that the program code is also included in the embodiment of the present invention even when the functions described in the above-described embodiment are realized in cooperation with application software or the like.
[0072]
Further, after the supplied program code is stored in the memory provided in the function expansion board of the computer or the function expansion unit connected to the computer, the CPU provided in the function expansion board or function expansion unit based on the instruction of the program code The present invention also includes a case where the functions of the above-described embodiment are realized by performing part or all of the actual processing.
[0073]
Examples of embodiments of the present invention are described below.
[Embodiment 1] A correction device for correcting a plurality of imaging signals from a plurality of output units of an imaging device,
Level adjustment means for adjusting the levels of the plurality of imaging signals, and correction coefficient determination means for determining a correction coefficient for reducing the level difference between the plurality of imaging signals based on temperature information. ,
A correction apparatus characterized in that the correction coefficient determined by the correction coefficient determination means is applied to the level adjustment means so that the level difference between the respective image pickup signals is reduced.
[Embodiment 2] It has an output level detection means for detecting an output level 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 that a level difference between the plurality of imaging signals becomes small.
[0074]
[Embodiment 3] The output level detection means includes an area selection means for selecting a predetermined area of the plurality of imaging signals, and an average level for calculating an average level in the area selected by the area selection means. The correction device according to claim 2, further comprising a calculation unit.
[0075]
[Embodiment 4] The output level detection means includes color signal selection means for selecting a predetermined color signal in the plurality of imaging signals,
4. The correction apparatus according to claim 1, wherein the output level detection result is generated based on a color signal selected by the color signal selection unit.
[0076]
[Embodiment 5] The correction coefficient determining means includes a gain error calculating means for calculating a gain error between the respective imaging signals from a plurality of detection results, and a threshold setting for setting a threshold value for allowing a level difference between the respective imaging signals. And a gain error signal calculated by the gain error calculation means is input, and a reference value is output when the gain error signal exceeds a threshold value, and when the gain error signal does not exceed the threshold value, an input gain error is output. A non-linear processing means for outputting
The correction apparatus according to any one of Embodiments 2 to 4, wherein a correction coefficient is determined based on a signal output from the nonlinear processing means.
[0077]
[Embodiment 6]
The correction coefficient determining means includes an evaluation value generating means for generating an evaluation value from the detection result of the output level detecting means, and an evaluation value average for averaging the evaluation values generated by the evaluation value generating means between a plurality of frames. And frame number setting means for setting the number of frames performed by the evaluation value averaging means,
The correction apparatus according to any one of embodiments 2 to 5, wherein a correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number setting means.
[0078]
[Embodiment 7] The correction coefficient determining means includes an evaluation value generating means for generating an evaluation value from a detection result of the output level detecting means, and an average of the evaluation values generated by the evaluation value generating means between a plurality of frames. Averaging means for performing, and frame number setting means for setting the number of frames to be averaged in the averaging means,
The correction device according to any one of embodiments 2 to 6, wherein a correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number setting means.
[0079]
[Embodiment 8] The correction apparatus according to Embodiment 7, further comprising: a frame number control unit that controls the number of frames to be averaged by the averaging unit in accordance with an image sensor or a temperature around the image sensor. .
[0080]
[Embodiment 9] The correction coefficient determination means includes an evaluation value generation means for generating an evaluation value from the detection result of the output level detection means, and a gain multiplication means for multiplying the evaluation value generated by the evaluation value generation means. And gain control means for variably controlling the gain by which the gain multiplying means multiplies the evaluation value according to the temperature of the image sensor or the periphery of the image sensor,
The correction apparatus according to any one of embodiments 2 to 8, wherein a correction coefficient is determined based on an evaluation value multiplied by a gain by the gain multiplication means.
[0081]
[Embodiment 10] A correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging device,
A level adjustment process for adjusting the levels of the plurality of image pickup signals, and a correction coefficient determination process for determining a correction coefficient for reducing a level difference between the plurality of image pickup signals based on temperature information. And
A correction method characterized in that the correction coefficient determined in the correction coefficient determination process is applied to the level adjustment process so that the level difference between the respective image pickup signals is reduced.
[Embodiment 11] It has an output level detection process for detecting an output level of the plurality of imaging signals,
11. The correction method according to claim 10, wherein the correction coefficient determination processing determines a correction coefficient so that a level difference between the plurality of imaging signals becomes small based on the level detection result.
[0082]
[Embodiment 12] The output level detection process includes an area selection process for selecting a predetermined area in the plurality of imaging signals, and an average level for calculating an average level in the area selected by the area selection process. A correction method according to claim 11, further comprising a calculation process.
[0083]
[Embodiment 13] The output level detection process includes a color signal selection process for selecting a predetermined color signal in the plurality of imaging signals,
The correction method according to any one of embodiments 10 to 12, wherein the output level detection result is generated based on a color signal selected by the color signal selection process.
[0084]
[Embodiment 14] The correction coefficient determination process includes a gain error calculation process for calculating a gain error between each imaging signal from a plurality of detection results, and a threshold setting for setting a threshold value for allowing a level difference between the imaging signals. Processing and the gain error signal calculated in the gain error calculation processing are input, and when the gain error signal exceeds a threshold, a reference value is output, and when the signal does not exceed the threshold, the input gain error is output. With non-linear processing
14. The correction method according to any one of embodiments 11 to 13, wherein a correction coefficient is determined based on a signal output from the nonlinear processing.
[0085]
[Embodiment 15]
The correction coefficient determination process includes an evaluation value generation process for generating an evaluation value from a detection result of the output level detection process, and an evaluation value average for averaging the evaluation value generated by the evaluation value generation process between a plurality of frames. And a frame number setting process for setting the number of frames performed in the evaluation value averaging process,
The correction method according to any one of embodiments 11 to 14, wherein a correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number setting process.
[0086]
[Embodiment 16] The correction coefficient determination process includes: an evaluation value generation process for generating an evaluation value from a detection result of the output level detection process; and an average of the evaluation values generated by the evaluation value generation process between a plurality of frames An averaging process, and a frame number setting process for setting the number of frames to be averaged in the averaging process,
16. The correction method according to any one of embodiments 11 to 15, wherein a correction coefficient is determined based on an evaluation value obtained by averaging the number of frames set by the frame number setting process.
[0087]
[Embodiment 17] The correction method according to Embodiment 16, further comprising: a frame number control process for controlling the number of frames to be averaged in the averaging process in accordance with an image sensor or a temperature around the image sensor. .
[0088]
[Embodiment 18] The correction coefficient determination processing includes evaluation value generation processing for generating an evaluation value from the detection result of the output level detection processing, and gain multiplication processing for multiplying the evaluation value generated by the evaluation value generation processing by a gain. And a gain control process that variably controls the gain by which the gain multiplication process multiplies the evaluation value by the temperature of the image sensor or the periphery of the image sensor,
18. The correction method according to any one of embodiments 11 to 17, wherein a correction coefficient is determined based on an evaluation value multiplied by a gain by the gain multiplication process.
[0089]
[Embodiment 19] 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 device,
A level adjustment process for adjusting the levels of the plurality of image pickup signals, and a correction coefficient determination process for determining a correction coefficient for reducing a level difference between the plurality of image pickup signals based on temperature information. And
A computer program that causes a computer to execute adjustment so that a level difference between image pickup signals is reduced by applying the correction coefficient determined in the correction coefficient determination process to the level adjustment process.
[0090]
[Embodiment 20] A computer-readable recording medium, wherein the computer program according to Embodiment 19 is recorded in a computer-readable manner.
[0091]
【The invention's effect】
As described above, according to the present invention, since the degree of correction is controlled according to temperature information, when dynamic fluctuation such as temperature fluctuation occurs, correction can be performed in real time, Steps appearing in the image can be eliminated satisfactorily.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating a configuration example of a video camera to which a first embodiment of the present invention is applied and to which the present invention is applied.
FIG. 2 is a diagram illustrating a rectangular area at a boundary portion 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 illustrating a gain correction characteristic with respect to a gain-up amount.
FIG. 5 is a block diagram showing a configuration example of means for executing a gain adjustment value calculation procedure in the first embodiment;
FIG. 6 is a diagram showing input / output characteristics of a limiter in the first embodiment.
FIG. 7 is a block diagram showing a configuration example of integration means in the first embodiment.
FIG. 8 is a diagram showing a control characteristic of a correction amount in the first embodiment.
FIG. 9 is a block diagram illustrating a configuration example of a unit that executes a gain adjustment value calculation procedure according to the second embodiment;
FIG. 10 is a block diagram showing a configuration example of integrating means in the second embodiment.
FIG. 11 is a diagram showing coefficient control characteristics in the second embodiment.
FIG. 12 is a block diagram showing a configuration example of means for executing a gain adjustment value calculation procedure in the third embodiment;
FIG. 13 is a diagram illustrating limiter threshold control characteristics according to the third embodiment;
FIG. 14 is a block diagram illustrating an example of a conventional imaging apparatus.
[Explanation of symbols]
100 CCD area sensor
101 photoelectric conversion unit and vertical transfer unit
103, 104 Horizontal transfer section
105, 106 Output amplifier
107, 108 Imaging signal output terminal
109, 110 Analog front end
111, 112 Black level detection and correction means
113, 114 Gain adjusting means
115 Screen composition means
116 Step evaluation value generating means
117 Microcomputer that controls the system
118 Camera signal processing means
119 Output terminal
120 Rewritable non-volatile memory
121 thermometer

Claims (7)

A correction device that corrects a plurality of imaging signals from a plurality of output units of an imaging element,
Level adjusting means for adjusting the levels of the plurality of imaging signals;
Output level detection means for detecting the level of the imaging signal;
Correction coefficient determining means for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information;
The correction coefficient determination means includes
Evaluation value generation means for generating an evaluation value from the detection result of the output level detection means;
Evaluation value averaging means for averaging evaluation values generated by the evaluation value generating means between a plurality of frames;
Frame number setting means for setting the number of frames to be averaged in the evaluation value averaging means;
Gain error calculating means for calculating a gain error between the plurality of imaging signals from an evaluation value obtained by averaging the number of frames set by the frame number setting means;
Threshold setting means for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals;
When a gain error calculated by the gain error calculation means is input, if a gain error between the imaging signals exceeds a threshold set by the threshold setting means, a predetermined reference value is output, Non-linear processing means for outputting the input gain error as it is when the gain error does not exceed the threshold,
The correction coefficient determining means determines the correction coefficient based on a signal output from the nonlinear processing means,
The number of frames to be averaged by the evaluation value averaging means in order to give the correction coefficient determined by the correction coefficient determining means to the level adjusting means so that the level difference between the plurality of image pickup signals is reduced. A correction apparatus, further comprising a frame number control means for controlling the image according to the image sensor or a temperature around the image sensor. A correction device that corrects a plurality of imaging signals from a plurality of output units of an imaging element,
Level adjusting means for adjusting the levels of the plurality of imaging signals;
Output level detection means for detecting the level of the imaging signal;
Correction coefficient determining means for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information;
The correction coefficient determination means includes
A step evaluation value generating means for generating an evaluation value from the detection result of the output level detecting means;
Gain error calculation means for calculating a gain error between the plurality of imaging signals from the evaluation value generated by the step evaluation value generation means;
Threshold setting means for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals;
When a gain error calculated by the gain error calculation means is input, if a gain error between the imaging signals exceeds a threshold set by the threshold setting means, a predetermined reference value is output, Non-linear processing means for outputting the input gain error as it is when the gain error does not exceed the threshold,
Gain means for multiplying a signal output from the nonlinear processing means;
Gain control means for controlling the gain applied to the signal by the gain means in accordance with the image sensor or the temperature around the image sensor;
The correction coefficient determining means determines the correction coefficient based on the signal multiplied by the gain by the gain means,
A correction apparatus, characterized in that the correction coefficient determined by the correction coefficient determination means is applied to the level adjustment means so that the level difference between the plurality of image pickup signals is reduced.   An imaging apparatus comprising: the correction apparatus according to claim 1 or 2; and the imaging element. A correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
A level adjustment step for adjusting the levels of the plurality of imaging signals;
An output level detecting step for detecting the level of the imaging signal;
A correction coefficient determining step for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information,
The correction coefficient determination step includes
An evaluation value generation step of generating an evaluation value from the detection result in the output level detection step;
An evaluation value averaging step of averaging the evaluation values generated in the evaluation value generation step between a plurality of frames;
A frame number setting step for setting the number of frames to be averaged in the evaluation value averaging step;
A gain error calculating step of calculating a gain error between the plurality of imaging signals from an evaluation value obtained by averaging the number of frames set in the frame number setting step;
A threshold setting step for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals;
When the gain error calculated in the gain error calculation step is input, if the gain error between the imaging signals exceeds the threshold set in the threshold setting step, a predetermined reference value is output, A non-linear processing step of outputting the input gain error as it is when the gain error does not exceed the threshold,
The correction coefficient determination step determines the correction coefficient based on the signal output in the nonlinear processing step,
The number of frames to be averaged in the evaluation value averaging step in order to give the correction factor determined in the correction factor determination step to the level adjustment step so that the level difference between the plurality of imaging signals is reduced. A correction method further comprising a frame number control step of controlling the image according to the temperature of the image sensor or the periphery of the image sensor. A correction method for correcting a plurality of imaging signals from a plurality of output units of an imaging element,
A level adjustment step for adjusting the levels of the plurality of imaging signals;
An output level detecting step for detecting the level of the imaging signal;
A correction coefficient determining step for determining a correction coefficient for reducing a level difference between the plurality of imaging signals based on temperature information,
The correction coefficient determination step includes
A step evaluation value generation step for generating an evaluation value from the detection result in the output level detection step,
A gain error calculating step of calculating a gain error between the plurality of imaging signals from the evaluation value generated in the step evaluation value generating step;
A threshold setting step for setting a threshold for allowing a subject-dependent level difference between the plurality of imaging signals;
When the gain error calculated in the gain error calculation step is input, if the gain error between the imaging signals exceeds the threshold set in the threshold setting step, a predetermined reference value is output, If the gain error does not exceed the threshold value, a nonlinear processing step that outputs the input gain error as it is,
A gain step of multiplying a signal output in the non-linear processing step;
A gain control step of controlling the gain applied to the signal in the gain step according to the image sensor or the temperature around the image sensor;
The correction coefficient determining step determines the correction coefficient based on the signal multiplied by the gain in the gain step,
A correction method characterized in that the correction coefficient determined in the correction coefficient determination step is applied to the level adjustment step so that the level difference between the plurality of imaging signals is reduced.   A computer-readable storage medium storing a program for causing a computer to execute each step of the correction method according to claim 4.   A program for causing a computer to execute each step of the correction method according to claim 4 or 5.

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