JP4159965B2 - Image processing device - Google Patents

Description

  The present invention relates to an image processing apparatus, and more particularly to an image processing apparatus that executes white balance processing.

  In the white balance processing of an imaging apparatus including a solid-state imaging device such as a CCD (Charge Coupled Device), color difference signals (RY, BY) that are differences between color signals and luminance signals obtained by imaging a subject. Signal) is averaged over the entire screen and a signal approximating the value obtained from the achromatic portion of the general subject is output. Based on the fact that the average value of this color difference signal over the entire screen is zero if the white balance is correct, and that the average value changes corresponding to the change in color temperature if the illumination of the subject changes. The amount of change is detected. The R gain and the B gain are calculated from the amount of change based on the black body radiation characteristics. Using these gains, white balance can be adjusted.

  By the way, when the shooting screen is one green color (single color), it is determined that the averaged color difference signal needs to be achromatic, and an erroneous control signal may be output. As a result, a phenomenon of so-called green reproducibility deterioration (so-called “color pull-in”) occurs.

  Thus, for example, Japanese Patent Laid-Open No. 2000-78605 (Patent Document 1) discloses a white balance control device that performs white balance control by multiplying an input image signal by a white balance gain. This apparatus passes a signal processing circuit that calculates a luminance signal and a color difference signal from an image signal for each pixel constituting an image, and the origin of a color vector coordinate whose vector direction and length represent hue and saturation. The black body radiation locus is divided into two regions with the origin as the boundary, and based on the approximate line obtained by combining the approximate lines obtained for each of the divided regions, the vicinity of the approximate line from the color difference signal of each pixel A white balance control circuit that calculates the white balance gain based on the result of integrating the selected color difference signal and the approximate line, and multiplying the color difference signal of each pixel by the white balance gain Including a multiplication circuit.

  According to this white balance control device, the multiplication circuit calculates the correction value of the color difference signal from the white balance gain and the color difference signal. The white balance control is executed based on this correction value so that the color difference signal to be corrected does not deviate from the black body radiation locus.

  Further, as a method for preventing color “drawing”, for example, Japanese Patent Laid-Open No. 9-307923 (Patent Document 2) discloses a color signal processing method for controlling an integration frame of color difference data serving as a reference for obtaining “shift amount”. Is disclosed. This method includes a step of setting a pull-in limit frame for limiting the range for white balance, and a step of changing the size of the pull-in limit frame in response to a change in the color temperature of the light source.

Furthermore, Japanese Patent Laid-Open No. 2001-8225 (Patent Document 3) directly calculates the R gain and B gain for achromatic color from the “deviation amount”, and these gains are set based on the black body radiation curve. Disclosed is a technique for determining whether or not a combination of gains is present.
JP 2000-78605 A JP-A-9-307923 JP 2001-8225 A

  However, according to the method of controlling the integration frame, the following problems occur. First, if the integration frame is made small, it is possible to suppress the pulling of a single color, but the range of the color temperature that can be applied may be narrowed. Or, it becomes easy to cause a malfunction called a lock that stops in a state where the white balance is lost, and the integration frame may not be made extremely small.

  Secondly, when the shape is asymmetric on the color vector, a phenomenon that the convergence point of the white balance is shifted from the origin tends to occur. Therefore, in reality, a symmetric rectangle covering the black body radiation curve on the color vector is obtained. As a result, the reality is that it is not always sufficient for pulling in a single color. Furthermore, since the amount of color shift frequently changes under illumination such as a fluorescent lamp, the color may fluctuate if a gain that becomes an achromatic color is directly calculated.

  The present invention has been made to solve the above-described problems, and its object is to reduce malfunctions in white balance processing, to reproduce colors stably and satisfactorily, and to load hardware and software. It is an object of the present invention to provide an image processing apparatus capable of reducing the above problem.

  An image processing apparatus according to a first aspect of the present invention is based on a storage means for storing data used for white balance processing control, a current value of the first color gain and a second value based on a signal from the image sensor. Based on the current value calculation means for calculating the current value of the color gain, the set value stored in advance in the storage means, and the calculated current value of the first color gain. Based on the first correction value calculation means for calculating the correction value and the black body radiation characteristic relating the first color gain and the second color gain to the second correction value from the first color gain correction value. The second color gain correction value based on the second correction value calculation means for calculating the color gain correction value, the current value of the second color gain and the correction value of the second color gain. To determine whether the execution of white balance processing according to the Comprising a switching judgment unit, when the execution of the white balance processing is determined to be appropriate, and an execution means for executing the white balance processing according to the correction value of the second color gain.

  According to the first invention, the image processing device controls white balance processing based on a signal from the image sensor with respect to a predetermined region (for example, IQ integration frame). When the current value calculating unit calculates the current value of the first color gain and the current value of the second color gain based on the signal from the image sensor, the first correction value calculating unit stores the setting stored in advance. A correction value of the first color gain is calculated based on the value and the calculated current value of the first color gain. For example, when the set value is added to the current value of the first color gain, a correction value for the first color gain is calculated. The second correction value calculating means obtains a correction value for the second color gain from the correction value for the first color gain based on the black body radiation characteristic relating the first color gain and the second color gain. calculate. The appropriateness determination means executes the white balance process using the second color gain correction value based on the second color gain current value and the second color gain correction value thus calculated. Determine whether is appropriate. If it is determined that the execution of the white balance process is appropriate, the execution unit executes the white balance process using the correction value of the second color gain. In this way, when the correction value of the second color gain deviates from the relationship of the black body radiation characteristic, the white balance process is not executed. Accordingly, it is possible to provide an image processing apparatus that can prevent a decrease in color reproducibility due to execution of unnecessary white balance processing.

  In the image processing apparatus according to the second invention, in addition to the configuration of the first invention, the storage means stores characteristic data representing a blackbody radiation characteristic calculated in advance. The second correction value calculating means calculates a correction value for the second color gain from the characteristic data and the correction value for the first color gain.

  According to the second invention, the characteristic data representing the black body radiation characteristic is stored in advance in the storage means, for example, as map format data or as a function expression, whereby the image processing apparatus controls white balance processing. Can be executed.

  In the image processing apparatus according to the third invention, in addition to the configuration of the first or second invention, the appropriateness determination means includes a difference between the current value of the second color gain and the correction value of the second color gain. Is less than a predetermined difference, it is determined that execution of the white balance process according to the correction value of the second color gain is appropriate. When the difference between the current value of the second color gain and the correction value of the second color gain is greater than a predetermined difference, the appropriateness determining unit performs white according to the correction value of the second color gain. It is determined that the execution of the balance process is inappropriate.

  According to the third invention, when the difference between the current value of the second color gain and the correction value of the second color gain is less than a predetermined difference, white that uses the correction value of the second color gain. Balance processing is executed. On the other hand, when the difference between the current value of the second color gain and the correction value of the second color gain exceeds a predetermined difference, white balance processing using the correction value of the second color gain is executed. Not. That is, the white balance process is executed only when the correction value of the second color gain maintains the black body radiation characteristic with the correction value of the first color gain. Colors can be reproduced stably and satisfactorily while preventing occurrence of malfunctions during execution of processing.

  An image processing apparatus according to a fourth invention, in addition to the configuration of any one of the first to third inventions, for calculating a color difference signal that is a difference between a color signal and a luminance signal for each pixel of the image sensor. The average value and the white balance are consistent with the average value calculating means for calculating the average value of each color difference signal in the predetermined area, which is the target area of the white balance process. Change amount calculating means for calculating a change amount that is a difference from the color difference signal when the image is being detected, and determination means for determining whether or not to execute white balance processing based on the change amount. When the determination unit determines that the white balance process is to be executed, the second correction value calculation unit calculates a correction value for the second color gain from the correction value for the first color gain.

  According to the fourth aspect of the invention, the white balance processing is performed based on the amount of change that is the difference between the average value of each color difference signal in the white balance processing target area and the color difference signal when the white balance is matched. It is determined whether or not to execute. This determination is made before the second correction value calculation means calculates the second color gain correction value. In this way, when the white balance processing is unnecessary, it is not necessary to execute processing such as calculation of the correction value of the second color gain, so that the load on the hardware or software can be reduced.

  In addition to the configuration of the fourth invention, the image processing apparatus according to the fifth invention determines that the white balance process is to be executed when the amount of change is within a predetermined range.

  According to the fifth invention, since the correction value of the second color gain is calculated only when the amount of change is within a predetermined range, the second value in the case where the deviation from the black body radiation characteristic occurs. The color gain correction value and the first color gain correction value are not calculated. As a result, the white balance process is not executed, and the occurrence of malfunction can be prevented.

  In addition to the configuration of the fourth or fifth invention, the image processing apparatus according to the sixth invention further calculates a ratio between the change amount of the first color gain and the change amount of the second color gain. And means for calculating a reference ratio between the current value of the first color gain and the black body radiation characteristic and the current value of the first color gain. The determination means includes a ratio determination means for determining that white balance processing is to be executed based on the ratio and the reference ratio.

  According to the sixth invention, the ratio between the change amount of the first color gain and the change amount of the second color gain, the value calculated from the current value of the first color gain and the black body radiation characteristic, The execution of the white balance processing can be controlled based on the reference ratio with the current value of the color gain of 1. Thereby, it is possible to determine at an early stage whether or not to execute the white balance processing.

  The image processing apparatus according to the seventh invention, in addition to the configuration of the sixth invention, determines that the ratio determining means executes white balance processing based on a difference between the ratio and the reference ratio.

  According to the seventh aspect, it is possible to determine at an early stage whether or not to execute the white balance processing based on the current value of the first color gain and the current value of the second color gain.

  In the image processing apparatus according to the eighth invention, in addition to the configuration of the sixth invention, the ratio determining means performs white balance processing when the difference between the ratio and the reference ratio is included in a predetermined range. It is determined to execute.

  According to the eighth invention, the reference ratio between the current value of the first color gain and the black body radiation characteristic and the current value of the first color gain, and the amount of change in the first color gain The white balance process can be executed only when the difference from the ratio with the change amount of the second color gain is included in the predetermined range. Therefore, the white balance process based on the correction value that deviates from the black body radiation characteristic is not executed, so that the malfunction can be prevented while preventing the color reproducibility from being lowered.

  In addition to the configuration of the fourth invention, in the image processing apparatus according to the ninth invention, the storage unit is responsive to a combination of a sign of the first color gain change amount and a sign of the second color gain change amount. Each preset reference ratio is stored. The image processing apparatus further checks the sign of the first color gain change amount and the sign of the second color gain change amount based on the first color gain change amount and the second color gain change amount. And a determination means for determining a reference ratio based on the confirmed sign of the change amount of the first color gain and the sign of the change amount of the second color gain. The determination means includes a ratio determination means for determining that white balance processing is to be executed based on the ratio and the reference ratio.

  According to the ninth aspect, when the sign confirmation unit confirms the sign (that is, positive / negative) of the first color gain change amount and the second color gain change amount, the determination means sets in advance according to the sign. Determine the reference ratio that is being used. The ratio determining unit determines whether to execute the white balance process based on the ratio between the first color gain change amount and the second color actual change amount and the determined reference ratio. In this way, for example, when the current convergence point is set as the origin, the direction of change (for example, the quadrant in the coordinate plane of the change amount of the color gain) can be confirmed by confirming the sign. Also, the reference ratio is easily determined. Therefore, it is possible to simply prevent malfunction by determining whether or not to execute the white balance processing based on the reference ratio.

  In addition to the configuration of the ninth invention, the image processing apparatus according to the tenth invention stores the change amount of the first color gain and the change amount of the second color gain, respectively. The sign confirmation means reads out the stored sign representing the first color gain change amount and the second color gain change amount, and thereby the sign of the first color gain change amount and the second color gain. Check the sign of the amount of gain change.

  According to the tenth aspect, when the first color gain change amount and the second color gain change amount are calculated and stored in the storage unit, the sign confirmation unit includes the first color gain change amount. Then, the sign representing the change amount of each second color gain is read, and the sign of the change amount of the first color gain and the sign of the change amount of the second color gain are confirmed. Therefore, the image processing apparatus can sequentially determine whether or not to execute the white balance process, so that the color reproducibility can be kept good according to the change in the signal input from the image sensor, Occurrence of malfunction can be prevented.

  In the image processing apparatus according to the eleventh invention, in addition to the configuration of the ninth or tenth invention, the ratio determining means determines to execute the white balance processing based on the difference between the ratio and the reference ratio.

  According to the eleventh aspect of the invention, the white balance process can be executed only when the ratio between the change amount of the first color gain and the change amount of the second color gain is included in a predetermined range, for example. Therefore, the white balance process when the ratio deviates from the predetermined range is not reliably executed. Thereby, malfunction of white balance processing can be prevented.

  In addition to the configuration of the eleventh invention, the image processing apparatus according to the twelfth invention is configured such that the ratio determining means performs white balance processing when the difference between the ratio and the reference ratio is included in a predetermined range. It is determined to execute.

  According to the twelfth aspect, when the difference between the ratio and the reference ratio is included in the predetermined range, the determination unit determines to execute the white balance process. In this way, since the conditions for dedicating the white balance processing can be minimized, malfunction of the white balance processing can be simply prevented.

  According to the present invention, the image processing apparatus can reduce malfunctions in white balance processing, reproduce colors stably and satisfactorily, and reduce the load on hardware and software.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
With reference to FIG. 1, the configuration of an image processing apparatus 1000 according to an embodiment of the present invention will be described. FIG. 1 is a block diagram conceptually showing the functional configuration of the image processing apparatus 1000.

  As shown in FIG. 1, the image processing apparatus 1000 includes a signal input unit 1140, a signal processing circuit 100, a memory 116, and a signal output unit 1180. The signal processing circuit 100 includes a color difference signal value calculation unit 150, an average value calculation unit 152, a current value calculation unit 154, a change amount calculation unit 156, a correction value calculation unit 158, a determination unit 160, and a white balance execution. Part 162. The image processing device 1000 is connected to the solid-state image sensor 112 and the image display device 120. Light from the lens 110 is input to the solid-state image sensor 112.

  A signal from the solid-state imaging device 112 is input to the signal input unit 1140. This signal is input to the signal processing circuit 100 after predetermined processing (for example, digital conversion) is performed. The signal processing circuit 100 executes a predetermined process based on the input signal and data stored in the memory 116. This process will be described later. The signal output unit 1180 performs predetermined processing on the signal from the signal processing circuit 100 and then outputs the signal to the image display device 120.

  The color difference signal calculation unit 150 calculates a color difference signal value that is a difference between a color signal and a luminance signal for each pixel of the solid-state imaging device 112. The average value calculation unit 152 calculates the average value of each color difference signal value in the region to be subjected to white balance processing. This area is a preset area. The current value calculation unit 154 calculates the current value of the color gain (for example, R gain, B gain, etc.) based on the signal from each pixel. The change amount calculation unit 156 calculates the difference between the color difference signal value and the average value when the white balance is matched in the region as the change amount.

  The correction value calculation unit 158 calculates a correction value from the current color gain value. This calculation is performed, for example, by adding an adjustment value stored in advance to the current value of the color gain. Further, the correction value calculation unit 158 calculates a correction value of the second color gain from the correction value of the first color gain for two color gains having a black body radiation characteristic relationship.

  Based on the current value or correction value of the color gain, the determination unit 160 determines whether to execute white balance processing using the color gain correction value, or whether to execute the white balance processing itself. .

  The white balance control unit 162 uses the color gain correction value or the current value to calculate and output a color gain for executing white balance processing.

  As described above, the signal processing circuit 100 is a circuit configured to realize a plurality of functions as described above. That is, the color difference signal calculation unit 150, the average value calculation unit 152, the current value calculation unit 154, the change amount calculation unit 156, and the correction value calculation unit 158 are realized by the color difference data integration circuit 104, for example. The determination unit 106 and the white balance execution unit 162 are realized by the white balance control circuit 106.

  Accordingly, an aspect of a specific configuration of the image processing apparatus 1000 will be described with reference to FIG. FIG. 2 is a block diagram showing the configuration of the image processing apparatus 1000.

  As shown in FIG. 2, the image processing apparatus 1000 includes an A / D (Analog to Digital) conversion circuit 114 connected to the solid-state imaging device 112, a signal processing circuit 100 connected to the A / D conversion circuit 114, It includes a memory 116 for storing data used for processing by the signal processing circuit 100 or calculated data, and a signal output IF (Interface) 118 connected to the signal processing circuit 100. The signal processing circuit 100 includes a color difference data integration circuit 104 and a white balance control circuit 106. The signal output IF 118 is connected to the image display device 120.

  The A / D conversion circuit 114 is one mode of the signal input unit 1140 shown in FIG. The color difference data integration circuit 104 is configured to realize the color difference signal calculation unit 150, the average value calculation unit 152, the current value calculation unit 154, the change amount calculation unit 156, and the correction value calculation unit 158 in FIG. Circuit.

  The white balance control circuit 106 is one mode of the white balance execution unit 162 in FIG. The arithmetic circuit 108 is a circuit configured to realize the determination unit 106 and the white balance execution unit 162 in FIG.

  Note that these circuit configurations are not limited to those shown in FIG. 2, and may be any configurations that can realize the functions shown in FIG. 1 is configured in advance as a program and stored in the memory 116 in advance, and a series of operations are executed in a computer by a CPU (Central Processing Unit) or other arithmetic processing unit. You may do it.

  In FIG. 2, the image of the subject collected by the lens 110 is converted into an electrical signal by one solid-state imaging device 112. The electric signal is input to the A / D conversion circuit 114 and converted from an analog signal to a digital signal. When this digital signal is input to the signal processing circuit 100, the color difference data integration circuit 104 executes a predetermined calculation process, and the white balance control circuit 106 executes a white balance process based on the calculation result. These processes will be described later. The processed signal is output to the image display device 120 via the signal output IF 118.

  With reference to FIG. 3, a control structure of the image processing apparatus 1000 according to the first embodiment of the present invention will be described based on a flowchart. FIG. 3 is a flowchart showing a procedure of processing executed by the signal processing circuit 100 of the image processing apparatus 1000.

  In S102, the signal processing circuit 100 receives a signal via the A / D conversion circuit 114.

  In S1021, the signal processing circuit 100 performs white balance from the color difference signal (R−Y, B−Y) that is the difference between the color signal (R, B) and the luminance signal (Y) included in the received signal. The difference between the color difference signal and the calculated color difference signal when the two are matched is calculated as the amount of change. In this way, the B gain change amount and the R gain change amount are calculated.

  In S1022, the signal processing circuit 100 confirms the ratio of the change amount of the color gain, and determines whether or not the allowable range in which the color shift is significantly generated from the black body radiation characteristic is determined. For example, it is confirmed whether or not the rate of change is below a predetermined rate of change. If it is determined that the amount of change in color gain exceeds the allowable range (YES in S1022), the process proceeds to S104. If not (NO in S1022), the process proceeds to S118.

  In S104, signal processing circuit 100 acquires the current value of R gain and the current value of B gain from the received signal.

  In S106, signal processing circuit 100 temporarily stores the current values of R gain and B gain in a predetermined area (for example, a work memory area) of memory 116.

  In S108, the signal processing circuit 100 calculates a correction value for B gain by adding a predetermined set value β (adjustment value β calculated from the color difference data value) to the current value of B gain. .

  In S110, the signal processing circuit 100 calculates an R gain correction value from the B gain correction value based on the black body radiation characteristic. In this calculation, for example, a function expression of R gain and B gain having a relationship of black body radiation characteristics, map data, and the like are used. The function formula, map data, and the like are stored in the memory 116 in advance.

  In S112, signal processing circuit 100 determines whether or not the difference between the correction value for R gain and the current value for R gain is included in a predetermined range σ. If it is determined that the difference between the correction value of R gain and the current value of R gain is included in a predetermined range σ (YES in S112), the process proceeds to S114. If not (NO in S112), the process proceeds to S116.

  In S114, the white balance control circuit 106 executes white balance processing based on the correction value. When this process is executed, the B gain correction value (B + β) calculated in S108 is set as the B gain. Further, a correction value based on the black body radiation characteristic calculated in S110 is set as a correction value for the R gain.

  In S116, the white balance control circuit 106 executes white balance processing based on the current color gain value. When this process is executed, the current value of the B gain and the current value of the R gain stored in the memory 116 are set as the B gain and the R gain, respectively. That is, the white balance process is executed without using the R gain correction value and the B gain correction value.

  In S118, the signal processing circuit 100 outputs signals of the set B gain and the R gain to the image display device 120.

  Regarding the operation of the image processing apparatus 1000 according to the present embodiment based on the above-described structure and flowchart, a case where white balance processing based on a correction value is executed and a case where white balance processing based on a current value is executed are described. To do.

[When executing white balance processing based on correction values]
When the signal of the subject acquired by the solid-state image sensor 112 is input to the image processing apparatus (S102), the change amount of the color gain is calculated (S1021). When the ratio of the change amount of the color gain exceeds the allowable range of the ratio determined from the black body radiation characteristic (YES in S1022), the current value of R gain and the current value of B gain are acquired (S104). Each current value is temporarily stored in the memory 116 (S106).

  A correction value of B gain is calculated from the current value of B gain and a predetermined set value β (S108), and a correction value of R gain is calculated based on the correction value of B gain and the black body radiation characteristic ( S110).

  When the difference between the correction value of R gain and the current value of R gain is included in a predetermined range (YES in S112), signal processing circuit 100 performs white balance based on the correction value of color gain. Judge that the execution of the process is appropriate. When the signal processing circuit 100 sets the R gain correction value and the B gain correction value as the R gain and the B gain (S114), the image processing apparatus 1000 outputs the R gain and the B gain to the image display apparatus 120 ( S118).

[When executing white balance processing based on the current value]
When the difference between the R gain correction value and the current value of R gain is not included in the predetermined range (NO in S112), signal processing circuit 100 performs white based on the color gain correction value. It is determined that the execution of the balance process is inappropriate. When the signal processing circuit 100 sets the current value of the R gain and the current value of the B gain as the R gain and the B gain (S116), the image processing apparatus 1000 outputs the R gain and the B gain to the image display apparatus 120 ( S118).

  As described above, in the image processing apparatus 1000 according to the present embodiment, when a relationship based on the black body radiation characteristic is recognized between the R gain correction value and the B gain correction value (that is, the R gain value). When the difference between the correction value and the current value of the R gain is within a predetermined range), white balance processing based on the correction value is executed. When no relationship based on the black body radiation characteristic is recognized between the R gain correction value and the B gain correction value, the image processing apparatus 1000 executes white balance processing based on the current value. In this way, it is possible to prevent a decrease in color reproducibility. If the change amount of the color gain is larger than a predetermined value, the image processing apparatus 1000 does not execute white balance processing. Therefore, it is possible to prevent malfunctions such as color pull-in while maintaining good color restriction.

<Second Embodiment>
The image processing apparatus 1000 according to the second embodiment of the present invention will be described below. Note that the image processing apparatus 1000 according to the present embodiment has the same hardware configuration as the image processing apparatus 1000 according to the first embodiment described above. The effect is the same. Therefore, description thereof will not be repeated.

  With reference to FIG. 4, the control structure of image processing apparatus 1000 according to the present embodiment will be described. FIG. 4 is a flowchart showing a procedure of processing executed by the signal processing unit 100 of the image processing apparatus 1000. In the flowchart of FIG. 4, the same steps as those in the flowchart of FIG. 3 are given the same step numbers. These processes are the same. Therefore, those descriptions are not repeated here.

  In S201, the signal processing circuit 100 calculates a ratio between the B gain change amount and the R gain change amount from the color gain change amount calculated in S1021.

  In S202, the signal processing circuit 100 determines that the difference between the ratio (ε) preset from the black body radiation curve with respect to the B gain and the ratio of the obtained change amount is within a predetermined tolerance κ. Judge whether there is. If it is determined that the difference is within the range of tolerance κ (YES in S202), the process proceeds to S104. If not (NO in S202), the process proceeds to S118.

  An operation of the image processing apparatus 1000 according to the present embodiment based on the above-described structure and flowchart will be described. The description of the same operation as that of the first embodiment will not be repeated.

  The image processing apparatus 1000 calculates the change amount of the color gain based on the signal from the solid-state image sensor 112 (S1021), and further calculates the ratio between the R gain and the B gain (S201). If the difference between the ratio and the preset ratio ε is within the range of the allowable difference κ, the image processing apparatus 1000 calculates the correction value for the B gain and the correction value for the R gain (S108, S110). . Thereafter, the difference between the B gain correction value and the R gain correction value is calculated, and when the difference between the B gain correction value and the R gain correction value is within a predetermined range (YES in S112). The image processing apparatus 1000 executes white balance processing using the correction value (S114).

  As described above, the image processing apparatus 1000 according to the present embodiment determines whether or not the difference between the color gain change amount ratio and the predetermined ratio is an allowable difference. If the difference is within the tolerance range, the image processing apparatus 1000 executes white balance processing. In this way, the white balance process can be executed or stopped based on the color gain ratio, so that a malfunction can be prevented while preventing a decrease in color reproducibility.

<Third Embodiment>
The image processing apparatus 2000 according to the third embodiment of the present invention will be described below. This embodiment is different from the above-described embodiments in that the user of the image processing apparatus 2000 can arbitrarily set the error κ or ε.

  The configuration of the image processing apparatus 2000 will be described with reference to FIG. FIG. 5 is a block diagram illustrating an aspect of a specific configuration of the image processing apparatus 2000.

  As shown in FIG. 5, the image processing apparatus 2000 includes a setting button 130 in addition to the configuration of the image processing apparatus 1000. The setting button 130 is connected to the signal processing circuit 100, and the input setting value is stored in the memory 116. This set value includes a reference value for determining whether or not to execute white balance processing.

  The control structure of the image processing apparatus 2000 according to the present embodiment will be described with reference to FIG. FIG. 6 is a flowchart showing a procedure of processing executed by the signal processing circuit 100 of the image processing apparatus 2000. In the flowchart shown in FIG. 6, the same step numbers are assigned to the same processes as those in the flowcharts in the above-described embodiments. The processing for them is the same. Therefore, detailed description thereof will not be repeated here.

  In step S <b> 301, the signal processing circuit 100 of the image processing apparatus 2000 reads the allowable error κ from the memory 116. This allowable error κ is a value arbitrarily set in advance by the user of the image processing apparatus 2000 via the setting button 130.

  In S202, the signal processing circuit 100 determines that the difference between the ratio (ε) preset from the blackbody radiation curve with respect to the B gain and the ratio of the obtained change amount is the allowable error κ set by the user. Determine whether it is within range. If it is determined that the difference is within the range of allowable error κ (YES in S202), the process proceeds to S104. If not (NO in S202), the process proceeds to S118.

  The operation of image processing apparatus 2000 according to the present embodiment based on the above structure and flowchart will be described. Note that the same operations as those in the above-described embodiments are not repeated.

  When the user of the image processing apparatus 2000 inputs an allowable error κ for controlling whether or not to execute white balance processing via the setting button 130, the value is stored in the memory 116. When the image processing apparatus 2000 receives a signal from the solid-state imaging device 112 (S102), the signal processing circuit 100 calculates the change amount of the color gain and the ratio of the change amount (S1021, S201), and further permits the change from the memory 116. The error κ is read (S301). When the difference between the ratio between the B gain and the R gain and the predetermined ratio ε is within the allowable error κ (YES in S202), the image processing apparatus 2000 executes a predetermined white balance process ( S114 or S116).

  As described above, the image processing apparatus 2000 according to the present embodiment determines whether it is appropriate to execute the white balance process based on the errors κ and ε arbitrarily set in advance by the user. To do. Therefore, the image processing apparatus 2000 can control white balance processing corresponding to the user's preference.

<Fourth embodiment>
The image processing apparatus according to the fourth embodiment of the present invention will be described below. Note that the image processing apparatus according to the present embodiment has the same hardware configuration as the image processing apparatus 2000 according to the third embodiment described above. Their actions are the same. Therefore, those descriptions are not repeated.

  The data stored in the memory 116 of the image processing apparatus 2000 will be described with reference to FIG. FIG. 7 is a diagram showing the positional relationship between the change amount and change direction (sign) of the R gain and the change amount and change direction of the B gain. For example, if the change directions are both positive, it means that the color gain has shifted to the first quadrant. If the change direction of the R gain is positive and the change direction of the B gain is negative, it means that the color gain has shifted to the second quadrant. The reference ratio ε for convergence to the origin along the black body radiation curve from the changing direction of the R gain and B gain can be applied to the determination of the white balance processing.

  The control structure of the image processing apparatus 2000 will be described with reference to FIG. FIG. 8 is a flowchart showing a procedure of processing executed by the signal processing circuit 100 of the image processing apparatus 2000. In the flowchart shown in FIG. 8, the same step numbers are assigned to the same processes as those in the flowcharts in the above-described embodiments. The processing for them is the same. Therefore, those descriptions are not repeated.

  In S401, the signal processing circuit 100 confirms the sign (“+” or “−”) of the color gain change amount based on the data stored in advance in the memory 116. This confirmation is performed by comparing the data stored in the memory 116 with the change amount of the color gain and specifying a region where the change amount of the color gain exists. Thus, by confirming the sign of the change amount of the R gain and the B gain, the color deviation is confirmed as a quadrant on the vector plane. When the quadrant is confirmed, the ratio ψ set for each quadrant is determined.

  In S202, the signal processing circuit 100 determines whether or not the difference between the change ratio calculated in S201 and the ratio ψ set for each quadrant is within the range of γ. If it is determined that the difference between the calculated ratio and the set ratio ψ is within the range of γ (YES in S202), the process proceeds to S104. Otherwise (NO in S202), the process proceeds to S118.

  An operation of image processing apparatus 2000 according to the present embodiment based on the above-described structure and flowchart will be described. The description of the same operation as that in each of the above embodiments will not be repeated.

  When the image processing apparatus 2000 receives a signal from the solid-state imaging device 112 (S102), it calculates an R gain change amount and a B gain change amount, and further calculates a ratio of these change amounts (S201). When the image processing apparatus 2000 confirms the sign of the change amount (S401), it determines whether or not the difference between the ratio corresponding to the sign and the change amount ratio is within a predetermined range (S202). If the difference is within a predetermined range, the image processing apparatus 2000 executes white balance processing according to a predetermined condition (S114 or S116).

  As described above, the image processing apparatus 2000 according to the present embodiment is based on the change amount of the color gain calculated from the signal and the change amount data associated with the black body radiation characteristic stored in advance. Check the direction of color gain change (that is, either positive or negative). When this direction is confirmed, the ratio stored corresponding to the direction is read out. The image processing apparatus 2000 determines whether or not to execute white balance processing based on this ratio. In this way, it is possible to prevent the white balance process from being executed when the amount of change in the color gain deviates from the black body radiation characteristic, so that the color reproducibility is degraded or the image processing apparatus 2000 malfunctions. Can be prevented.

<Fifth embodiment>
Hereinafter, an image processing apparatus 2000 according to a fifth embodiment of the present invention will be described. Note that the image processing apparatus 2000 according to the present embodiment has the same hardware configuration as that of the above-described first embodiment. Their actions are the same. Therefore, description thereof will not be repeated.

  With reference to FIG. 9, a control structure of image processing apparatus 2000 according to the present embodiment will be described. FIG. 9 is a flowchart showing a procedure of processing executed by the signal processing circuit 100 of the image processing apparatus 2000. In the flowchart shown in FIG. 9, the same step numbers are assigned to the same processes as those in the flowcharts according to the above-described embodiments. The processing for them is the same. Therefore, description of those processes will not be repeated.

  In S <b> 501, the signal processing circuit 100 reads a value γ preset by a user of the image processing apparatus 2000 from the memory 116. This value can be arbitrarily set even when the image processing apparatus 2000 is not executing signal processing.

  In S202, the signal processing circuit 100 determines that the difference between the ratio between the change amount of the R gain and the change amount of the B gain and the ratio ψ set based on the quadrant of the color shift on the vector plane is the set value γ. Determine whether it is within range. If it is determined that the difference is within the range of set value γ (YES in S202), the process proceeds to S104. If not (NO in S202), the process proceeds to S118.

  An operation of image processing apparatus 2000 according to the present embodiment based on the above-described structure and flowchart will be described. The description of the same operation as the operation according to each of the above-described embodiments will not be repeated.

  When the image processing apparatus 2000 receives a signal from the solid-state imaging device 112 (S102), the signal processing circuit 100 calculates the change amount of the R gain and the change amount of the B gain, and further calculates the ratio of the change amounts. (S201). A preset allowable range γ is read from the memory 116 (S501), and the sign of the color gain change amount is confirmed (S401). If the difference between the ratio corresponding to the code and the change amount ratio is included in allowable range γ (YES in S202), image processing apparatus 2000 executes white balance processing in accordance with a predetermined condition (S114). Or S116).

  As described above, the image processing apparatus 2000 according to the present embodiment is based on the change amount of the color gain calculated from the signal and the change amount data associated with the black body radiation characteristic stored in advance. Check the direction of color gain change (that is, either positive or negative). When this direction is confirmed, the ratio stored corresponding to the direction is read out. The image processing apparatus 2000 determines whether or not to execute the white balance processing based on the allowable error range γ arbitrarily set by the user and the ratio. If it does in this way, the white balance process corresponding to a user's preference can be performed.

  As described above, each of the image processing apparatuses according to the first to fifth embodiments described in detail reproduces the color well with respect to the signal acquired by the solid-state imaging device 112 and does not cause a malfunction. Can be executed.

  In this case, since the correction value of the color gain is calculated based on the black body radiation characteristic, a phenomenon such as a single color pull-in can be reduced. Further, since the ideal correction value is not directly calculated based on the IQ integration frame from the change amount of the R gain and the change amount of the B gain, the limitation due to the hardware configuration can be avoided. Furthermore, since the software necessary for the processing using the IQ integration frame is unnecessary, the load on the software for realizing the image processing method can be reduced accordingly. As a result, it is possible to provide an image processing apparatus that can reproduce colors well and suppress malfunctions in white balance processing.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a block diagram showing the structure of the function of the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a block diagram showing the structure of the image processing apparatus which concerns on the 1st Embodiment of this invention. It is a flowchart showing the procedure of the process which the image processing apparatus which concerns on the 1st Embodiment of this invention performs. It is a flowchart showing the procedure of the process which the image processing apparatus which concerns on the 2nd Embodiment of this invention performs. It is a block diagram showing the structure of the image processing apparatus which concerns on the 3rd Embodiment of this invention. It is a flowchart showing the procedure of the process which the image processing apparatus which concerns on the 3rd Embodiment of this invention performs. It is a figure for demonstrating the variation | change_quantity of the color gain which the image processing apparatus which concerns on the 4th Embodiment of this invention uses. It is a flowchart showing the procedure of the process which the image processing apparatus which concerns on the 4th Embodiment of this invention performs. It is a flowchart showing the procedure of the process which the image processing apparatus which concerns on the 5th Embodiment of this invention performs.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 Signal processing circuit, 104 Color difference data integration circuit, 106 White balance control circuit, 110 Lens, 112 Solid-state image sensor, 114 A / D conversion circuit, 116 Memory, 118 Signal output IF, 120 Video display apparatus, 130 Setting button, 150 Color difference signal calculation unit, 152 average value calculation unit, 154 current value calculation unit, 156 change amount calculation unit, 158 correction value calculation unit, 160 determination unit, 162 white balance execution unit, 1000, 2000 image processing apparatus.

Claims (12)

An image processing apparatus for controlling execution of white balance processing based on a signal from an image sensor,
Storage means for storing data used for controlling the white balance processing;
Current value calculation means for calculating a current value of the first color gain and a current value of the second color gain based on a signal from the image sensor;
First correction value calculation means for calculating a correction value of the first color gain based on the set value stored in advance in the storage means and the calculated current value of the first color gain. When,
A second color gain correction value for calculating a second color gain correction value from the first color gain correction value based on a black body radiation characteristic relating the first color gain and the second color gain. Correction value calculation means for
Based on the current value of the second color gain and the correction value of the second color gain, it is determined whether or not the execution of the white balance process according to the correction value of the second color gain is appropriate. An appropriateness judging means for judging,
And an execution unit configured to execute the white balance process according to the correction value of the second color gain when it is determined that the execution of the white balance process is appropriate. The storage means stores characteristic data representing the blackbody radiation characteristic calculated in advance,
The image processing apparatus according to claim 1, wherein the second correction value calculation unit calculates the correction value of the second color gain from the characteristic data and the correction value of the first color gain. The appropriateness determining means includes
When the difference between the current value of the second color gain and the correction value of the second color gain is less than a predetermined difference, the white balance processing according to the correction value of the second color gain Is deemed appropriate,
When the difference between the current value of the second color gain and the correction value of the second color gain exceeds a predetermined difference, the white balance processing according to the correction value of the second color gain The image processing apparatus according to claim 1, wherein the execution of is determined to be inappropriate. The image processing apparatus further includes:
Signal calculating means for calculating a color difference signal that is a difference between a color signal and a luminance signal for each pixel of the image sensor;
An average value calculating means for calculating an average value of the color difference signals in a predetermined area, the area to be subjected to white balance processing;
A change amount calculating means for calculating a change amount that is a difference from the color difference signal when the average value and the white balance are matched;
Determining means for determining whether to execute the white balance processing based on the amount of change;
The second correction value calculation unit calculates a correction value of a second color gain from the correction value of the first color gain when the determination unit determines to execute the white balance process. 4. The image processing device according to any one of 3.   The image processing apparatus according to claim 4, wherein the determination unit determines to execute the white balance process when the amount of change is within a predetermined range. The image processing apparatus further includes:
Means for calculating a ratio between a change amount of the first color gain and a change amount of the second color gain;
Means for calculating a reference ratio between a current value of the first color gain and a value calculated from the black body radiation characteristic and a current value of the first color gain;
The image processing apparatus according to claim 4, wherein the determination unit includes a ratio determination unit that determines to execute the white balance process based on the ratio and the reference ratio.   The image processing apparatus according to claim 6, wherein the ratio determining unit determines to execute the white balance process based on a difference between the ratio and the reference ratio.   The image processing apparatus according to claim 6, wherein the ratio determination unit determines to execute the white balance process when a difference between the ratio and the reference ratio is included in a predetermined range. The storage means stores a reference ratio set in advance according to a combination of a sign of the first color gain change amount and a sign of the second color gain change amount,
The image processing apparatus further includes:
To confirm the sign of the first color gain change amount and the sign of the second color gain change amount based on the first color gain change amount and the second color gain change amount Sign confirmation means,
Determining means for determining the reference ratio based on the confirmed sign of the change amount of the first color gain and the sign of the change amount of the second color gain,
The image processing apparatus according to claim 4, wherein the determination unit includes a ratio determination unit that determines to execute the white balance processing based on the ratio and the reference ratio. The storage means stores a change amount of the first color gain and a change amount of the second color gain, respectively.
The sign confirming unit reads the stored sign indicating the first color gain change amount and the second color gain change amount, thereby obtaining a sign of the first color gain change amount and The image processing apparatus according to claim 9, wherein a sign of a change amount of the second color gain is confirmed.   The image processing apparatus according to claim 9, wherein the ratio determination unit determines to execute the white balance process based on a difference between the ratio and the reference ratio.   The image processing apparatus according to claim 11, wherein the ratio determination unit determines to execute the white balance process when a difference between the ratio and the reference ratio is included in a predetermined range.

Images