JP2004023205A - Device and method for processing color signal and camera device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize auto white balance with high performance and to improve image quality by correctly reproducing the colors of the whole image. <P>SOLUTION: A primary color signal of R (red), G (green) and B (blue) obtained by applying color splitting to a digital image signal obtained by being subjected to A/D conversion from a solid-state imaging device with color splitting processing of a luminance signal processing part 51, and a luminance signal (Y) of the digital image signal are inputted to an optical detector 52. The signals are respectively integrated in each field to determine the imaged state of the image signal on the basis of the integrated value and the number of integrated pixels. A digital filter performs pixel averaging processing of the digital image signal and on/off control of integration processing in an integration circuit for white balance control is performed in accordance with this determination result to perform auto white balance processing. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a color signal processing circuit and a color signal processing method capable of performing appropriate white balance processing on a color signal obtained by imaging a subject, and a camera device using the same.
[0002]
[Prior art]
Conventionally, when an image of a subject is captured using a solid-state image sensor such as a CCD image sensor, the entire white screen included in the subject shifts to red in a place where the color temperature is low, such as indoors, and is used in an outdoor environment. In places where the color temperature is high, the entire screen shifts to blue.
By the way, in a camera system using a solid-state imaging device as an imaging device, when the color temperature of a light source changes in order to project an achromatic white in an imaging result of imaging a white of a subject, for example, as shown in FIG. As described above, the white color moves along the blackbody radiation curve in accordance with the change in the color temperature, and the automatic white balance processing is performed so that the white color that appears to be colored becomes the achromatic white color. In FIG. 2, the horizontal axis represents the amplitude (gain) of the color difference signal BY, the vertical axis represents the amplitude of the color difference signal RY, and the origin is achromatic white.
In the automatic white balance processing, the R, G, and B primary color signals are integrated based on the additive color mixture shown in FIG. 3, that is, the idea that all the colors add up to produce a white color. The color temperature was determined and the white balance was adjusted.
[0003]
[Problems to be solved by the invention]
However, as described above, in the conventional color signal processing circuit that performs the color temperature inverse determination based on the data obtained by integrating all the pixel data, if the object to be imaged has various colors in a well-balanced manner. Although ideal, there is a problem that it is difficult to determine whether or not the integrated data has a bias in the color temperature change if the subject has a biased color such as a primary color or a complementary color (for example, see Japanese Patent Application Laid-Open No. 243557).
[0004]
Therefore, an object of the present invention is to provide a color signal processing circuit, a color signal processing method, and a camera device that can realize high-performance auto white balance and that can correctly reproduce the colors of the entire screen and improve image quality. Is to do.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, the present invention provides an input unit that inputs an image signal, a color separation unit that performs color separation on an image signal input by the input unit and outputs an RGB primary color signal and a luminance signal, Integrating means for integrating the primary color signal and the luminance signal obtained by the color separating means for each field, and determination for judging the imaging state of the image signal based on the integrated value and the number of integrated pixels obtained by the integrating means. Means, and white balance control means for controlling the white balance of the image signal based on the determination result of the determination means.
Also, the present invention performs a first integration process for each of the fields of an RGB primary color signal and a luminance signal obtained by color separation of an image signal, and captures the image signal based on the integrated value and the number of integrated pixels. The state is determined, and the white balance of the image signal is controlled according to the determination result.
[0006]
Further, according to the present invention, in a camera device having an image pickup unit for picking up an image of a subject and a color signal processing circuit for performing color signal processing of an image signal obtained by the image pickup unit, the color signal processing circuit is provided by the image pickup unit. Color separation means for color-separating the obtained image signal to output RGB primary color signals and luminance signals, integration means for integrating the primary color signals and luminance signals obtained by the color separation means for each field, Determining means for determining an imaging state of the image signal based on the integral value and the number of integrated pixels obtained by the integrating means; and white balance control for controlling a white balance of the image signal based on the determination result of the determining means Means.
[0007]
In a color signal processing circuit, a color signal processing method, and a camera device according to the present invention, a primary color signal and a luminance signal obtained by color-separating an image signal are integrated for each field, and an image is represented by the integrated value and the number of integrated pixels. Since the imaging state of the signal is determined and the white balance of the image signal is controlled based on the determination result, before integration for white balance control, a color close to a primary color or a complementary color or a color close to white is determined. It is possible to integrate the color signal information only when it is determined and the color is determined to be the color temperature change.
For example, only data when the color is determined as a color temperature change is used as data for auto white balance, or data when the color is determined as a color other than color temperature change is excluded from the data for auto white balance. can do.
Therefore, even when the primary color or the complementary color exists in the subject, the white balance can be accurately adjusted, and the performance of the auto white balance can be improved, and the color reproducibility and the image quality of the output image can be improved. can do.
[0008]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of a color signal processing circuit, a color signal processing method, and a camera device according to the present invention will be described.
FIG. 1 is a block diagram showing an overall configuration of a camera device to which an embodiment of the present invention is applied.
As shown, the camera device includes a lens 10, an image sensor 20, a preamplifier 30, an A / D converter 40, a digital signal processing circuit 50, and a system controller 60.
The imaging device 20 is a solid-state imaging device such as a CCD image sensor or a CMOS image sensor, and captures an image of a subject through the lens 10 and outputs an image signal as a result of the imaging.
The preamplifier 30 amplifies the image signal from the image sensor 20 and sends the amplified image signal to the A / D converter 40. The A / D converter 40 converts the analog image signal from the preamplifier 30 into a digital image signal, Output to the processing circuit 50.
[0009]
The digital signal processing circuit 50 is composed of a DSP (digital signal processor) or the like, performs various signal processing on the digital image signal input from the A / D converter 40, and converts the digital image signal into an analog signal as a final image signal. Output.
The system controller 60 controls the entire camera device, and stores, for example, a program 61 and the like necessary for processing the color signal in the digital signal processing circuit 50.
[0010]
Next, the digital signal processing circuit 50 in the present example will be described.
As illustrated, the digital signal processing circuit 50 of the present example has a luminance signal processing unit 51, an optical detector 52, and a D / A converter 53 as main components.
The luminance signal processing unit 51 performs color separation processing, auto white balance processing, gamma correction processing, color difference matrix processing, encoder processing, and the like of the digital image signal input from the A / D converter 40.
The optical detector 52 receives the luminance signal obtained by the color separation processing of the luminance signal processing unit 51, outputs the detection signal to the system controller 60, and receives the color signal processing control signal from the system controller 60. The luminance signal processing unit 51 performs a color signal determination process necessary for the automatic white balance process.
The D / A converter 53 converts the digital image signal processed by the luminance signal processing unit 51 back into an analog image signal and outputs it to a subsequent stage.
[0011]
In particular, in this example, the following processing is performed for color separation processing and auto white balance processing of digital image signals by the luminance signal processing unit 51 and the optical detector 52.
(1) R (red), G (green), and B (blue) primary color signals obtained by color separation of an input digital image signal by color separation processing of a luminance signal processing unit 51, and a digital image signal Is input to the optical detector 52, and these signals are integrated for each field, and the imaging state of the image signal is determined based on the integrated value and the number of integrated pixels.
(2) Then, in accordance with the result of the determination, the digital image signal is subjected to M (vertical) × N (horizontal) pixel averaging processing.
(3) Further, from the primary color signals of R (red), G (green), and B (blue) subjected to the pixel averaging process, data changes other than the color temperature change (colors close to the primary colors, colors close to the complementary colors) are detected. Then, an integration gate pulse for controlling on / off of the integration process for auto white balance is generated in real time.
(4) R (red), G (green), and B (red) obtained by color-separating the digital image signal by the luminance signal processing unit 51 only during the period in which integration is permitted by the integration gate pulse. (Blue) is integrated.
[0012]
Hereinafter, the configuration for performing the color signal processing of this example and the contents of the signal processing will be specifically described.
FIG. 4 is a block diagram showing the processing contents in the optical detector 52 of the digital signal processing circuit 50 described above.
The color signal processing circuit according to the present embodiment includes a hardware portion and a software portion including the system controller 60.
The hardware portion includes a pixel averaging circuit 110 for averaging pixel information of M stages in the vertical direction and N stages in the horizontal direction by a digital filter, and primary colors of G (green), R (red), and B (blue). A color signal determination circuit (saturation detection circuit) 120 for extracting a color saturation from signal information and determining any of a color close to white, a color close to a complementary color, and a color close to a primary color; a luminance signal or a color signal And an integration circuit (second integration means) 130 for integrating only the period in which integration is permitted by the above-described integration gate pulse.
[0013]
Further, in this example, an integration circuit (first integration means) 140 having the same configuration as the integration circuit 130 is mounted.
Then, in the integration circuit 140, primary color signals of R (red), G (green), and B (blue) obtained by color-separating a digital image signal corresponding to the imaging result of the imaging device 20 and a digital image signal Is integrated for each field, and the integrated values of the Y signal, the R, G, and B signals and the number of integrated pixels are passed to the system controller 60 as outputs.
The system controller 60 outputs control signals 1 and 2 for controlling the pixel averaging circuit 110 and the color signal determination circuit (saturation detection circuit) 120 based on the output result.
The pixel averaging circuit 110 performs a process of reducing the spatial frequency of the R, G, and B primary color signals obtained by color-separating the digital image signal using an M × N-stage filter (vertical M lines × horizontal N pixels) Average).
[0014]
Thereby, the number of vertical lines (M) and the number of horizontal pixels (N) are controlled by the control signal 2 from the system controller 60 based on the output result of the integration circuit 140.
As this control method, for example, the following example can be considered.
(1) If the values of R, G, and B output from the integration circuit 140 are biased, it is considered that a subject of a color close to the primary color or the complementary color occupies most of the screen, and the number of vertical lines is large. And the number of horizontal pixels is set to a large value, and a subject predicted to occupy most of the screen is regarded as having the same color.
(2) If the values of R, G, and B output from the integration circuit 140 are equal, it is predicted that various subjects exist in the screen, and therefore the number of vertical lines and the number of horizontal pixels Is set to a small value, and a pixel having a color close to a locally existing primary color or a complementary color is targeted.
[0015]
Further, the algorithm of the color signal determination circuit 120 converts the G, R, and B signal amount components into a color close to white (G, R, and B signal amounts are equal) and a complementary color, as shown in FIG. Close color (one signal amount of G, R, B is negligibly smaller than the other two), color close to the primary color (two signal amounts of G, R, B remain one Is negligibly small compared to the above).
The color signal determination circuit 120 has a configuration including a color information detection circuit 121, a color information determination circuit 122, and an integration gate pulse generation circuit 123, as shown in FIG. are doing.
[0016]
In the color information detection circuit 121, the G, R, and B components of the color signal are sequentially compared with an arbitrary color signal slice level by the comparator 121A, and if the color signal is equal to or higher than the color signal slice level, 1 is output. If it is, 0 is output. The output of the comparator 121A is sequentially shifted and latched by three latch circuits 121B, 121C, and 121D using D flip-flops in units of one pixel.
Then, the outputs of the latch circuits 121B, 121C, and 121D are output to the adder 121E, and the sum of the comparator outputs of the G, R, and B components of the color signal for each pixel is calculated. The setting of the color signal slice level in the comparator 121A is performed in real time by calculating a value from the output result of the integration circuit 140 by the system controller 60.
[0017]
The color information determination circuit 122 determines the color information of the color signal from the output of the color information detection circuit 121.
That is, if the sum of the outputs of the color information detection circuit 121 is 3, G ≒ R ≒ B, the color is close to white. If the sum is 2, the color is close to the complementary color. If the sum is 1, the color is close to the primary color.
In the color information determination circuit 122, the output of the color information detection circuit 121 is latched by a latch circuit 122A using a D flip-flop, and this value is compared with two comparators 122B and 122C and two parameters (a saturation determination level 1 and a saturation determination level). The determination is made based on the determination level 2) and the AND circuit 122D which performs AND of each comparison output.
For example, when the saturation determination level 1 = 3 and the saturation determination level 2 = 3, the output of the color information determination circuit 122 becomes 1 only when the color is close to white (the output of the color information detection circuit 121 is 3). It becomes.
When the saturation level 1 is set to 2 and the saturation level 2 is set to 1, a color close to the primary color (the output of the color information detection circuit 121 is 1) and a color close to the complementary color (color information detection circuit 121) are used. When the output of 121 is 2), the output of the color information determination circuit 122 becomes 1.
[0018]
The integration gate pulse generation circuit 123 includes an inverter circuit 123A and a switch circuit 123B, and realizes a function of inverting / forwarding the output of the color information determination circuit 122.
In this example, since the integration circuit 130 is designed to integrate during the period when the integration gate pulse is at the L level, the integration gate pulse generation circuit 123 integrates a color close to white by changing the polarity of the pulse. It is possible to make settings such as / no integration, integration / non-integration of colors close to complementary colors, and integration / no integration of colors close to primary colors.
Then, the integration circuit 130 integrates R, G, and B obtained by color-separating the image signal only during a period in which integration is permitted by the integration gate pulse generated by the color signal determination circuit 120. This makes it possible to integrate the color signal information only when it is determined that the color is at the time of color temperature change.
[0019]
According to the present embodiment as described above, at the time of auto white balance control, a color close to a primary color, a complementary color, or a color close to white is determined by a determination circuit before integration, and determined as a color at the time of color temperature change. Only when this is done, it becomes possible to integrate the color signal information. In other words, only the data when it is determined that the color at the time of color temperature change is used as the data for auto white balance, or the data when it is determined as the color other than the color temperature change is used as the data for auto white balance. It can be excluded.
Accordingly, even when the primary color or the complementary color exists in the subject in a biased manner, the white balance can be accurately adjusted, leading to an improvement in the performance of the auto white balance, and the color reproduction and the image quality of the camera device can be improved. .
[0020]
In the above embodiments, the case where the color signal processing circuit and the color signal processing method according to the present invention are configured as a camera device has been described, but the present invention is configured as a single color signal processing circuit and a single color signal processing method. It is also possible.
Further, in the above-described embodiment, the configuration in which the image signal is processed by the solid-state imaging device has been described. However, the present invention can be similarly applied to a device that processes an image signal input from another imaging unit or a medium. And can be applied to both still cameras and video cameras.
[0021]
【The invention's effect】
As described above, according to the color signal processing circuit, the color signal processing method, and the camera device of the present invention, a color close to a primary color, a complementary color, or a color close to white is not integrated by the determination circuit during auto white balance control. And the color signal information can be integrated only when the color is determined to be a color temperature change. Therefore, even when the primary color or the complementary color exists in the subject in a biased manner, the white balance can be accurately adjusted. As a result, the performance of the automatic white balance control can be improved, and the color reproduction and image quality of the output image can be improved.
[Brief description of the drawings]
FIG. 1 is a block diagram illustrating an overall configuration of a camera device to which an embodiment of the present invention has been applied.
FIG. 2 is an explanatory diagram showing a blackbody radiation curve on a vectorscope.
FIG. 3 is an explanatory diagram illustrating additive color mixture.
FIG. 4 is a block diagram showing processing contents in an optical detector of a digital signal processing circuit in the camera device shown in FIG. 1;
FIG. 5 is an explanatory diagram showing an algorithm in the color signal determination circuit shown in FIG.
FIG. 6 is a block diagram illustrating a configuration example of a color signal determination circuit illustrated in FIG. 4;
[Explanation of symbols]
Reference numeral 10: lens, 20: imaging element, 30: preamplifier, 40: A / D converter, 50: digital signal processing circuit, 60: system controller.

Claims (21)

Input means for inputting an image signal,
A color separation unit that performs color separation on the image signal input by the input unit and outputs an RGB primary color signal and a luminance signal;
Integrating means for integrating the primary color signal and the luminance signal obtained by the color separating means for each field,
Determining means for determining an imaging state of the image signal based on the integration value and the number of integrated pixels obtained by the integration means,
White balance control means for controlling the white balance of the image signal based on the determination result of the determination means,
A color signal processing circuit comprising: The color signal processing circuit according to claim 1, wherein the image signal is a signal captured by a solid-state imaging device. 2. The color signal according to claim 1, wherein said white balance control means includes a pixel averaging processing means for performing a vertical M × horizontal N pixel averaging process on the image signal based on the determination result by said determination means. Processing circuit. The white balance control means detects a data change other than a color temperature change from the RGB primary color signals obtained by the pixel averaging processing means, and generates an integration gate pulse for turning on / off white balance control integration processing. The color signal processing circuit according to claim 3, further comprising: 5. The color signal processing circuit according to claim 4, wherein said white balance control means performs said white balance control integration process only during a period in which integration is permitted by said integration gate pulse. 6. The color signal processing circuit according to claim 5, wherein an operation from the input of the image signal to the white balance control is performed by real-time processing. 7. The color signal processing circuit according to claim 6, further comprising: a first integration means for performing an integration process used for the determination by the determination means; and a second integration means for performing an integration process used for the white balance control. . A first integration process for each field is performed on the RGB primary color signal and the luminance signal obtained by color-separating the image signal, and the imaging state of the image signal is determined based on the integrated value and the number of integrated pixels. Controlling the white balance of the image signal according to the determination result,
A color signal processing method comprising: 9. The color signal processing method according to claim 8, wherein the image signal is a signal captured by a solid-state imaging device. 9. The color signal processing method according to claim 8, wherein pixel averaging processing of M vertical stages × N horizontal stages is performed on the image signal based on the determination result of the imaging state. A data change other than a color temperature change is detected from the RGB primary color signals obtained by the pixel averaging process, and the second integration process for white balance control is turned on / off according to the detection result. 11. The color signal processing method according to claim 10, wherein: 12. The color signal processing method according to claim 11, wherein a second integration process of the RGB primary color signals obtained by color-separating the image signal is performed only during a period in which the integration process is turned on. 13. The color signal processing method according to claim 12, wherein an operation from the input of the image signal to the white balance control is performed by real-time processing. 14. The color signal processing method according to claim 13, wherein the first integration processing and the second integration processing are performed by different integration means. In a camera device having an imaging unit that captures an image of a subject and a color signal processing circuit that performs color signal processing of an image signal obtained by the imaging unit,
The color signal processing circuit,
A color separation unit that performs color separation on an image signal obtained from the imaging unit and outputs an RGB primary color signal and a luminance signal;
Integrating means for integrating the primary color signal and the luminance signal obtained by the color separating means for each field,
Determining means for determining an imaging state of the image signal based on the integration value and the number of integrated pixels obtained by the integration means,
White balance control means for controlling the white balance of the image signal based on the determination result of the determination means,
A camera device characterized by the above-mentioned. 16. The camera device according to claim 15, wherein the imaging unit is a signal captured by a solid-state imaging device. 16. The camera device according to claim 15, wherein said white balance control means includes a pixel averaging processing means for performing a vertical M × horizontal N pixel averaging process on an image signal based on a determination result by said determination means. . The white balance control means detects a data change other than a color temperature change from the RGB primary color signals obtained by the pixel averaging processing means, and generates an integration gate pulse for turning on / off white balance control integration processing. 18. The camera device according to claim 17, comprising: 19. The camera device according to claim 18, wherein the white balance control means performs the white balance control integration process only during a period in which integration is permitted by the integration gate pulse. 20. The camera device according to claim 19, wherein an operation from the input of the image signal to the white balance control is performed by real-time processing. 21. The camera device according to claim 20, further comprising: a first integration unit that performs an integration process used for the determination by the determination unit; and a second integration unit that performs an integration process used for the white balance control.

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