JPH09331543A - Color area detection circuit and image pickup device using the circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a color area detection circuit detecting a specific color area with high accuracy with a simple configuration and to provide an image pickup device in which a picked-up image desired by a photographer is easily obtained. SOLUTION: Selectors 44, 45 are used to select in time division a reference color (x0+1) and a detection threshold level (xth) or a reference color (y0+1) and a detection threshold level (yth), and multipliers 47, 48 multiply the selected values with a luminance signal WU from a W matrix section 41. From the result of the multiplier 47, an image pickup signal DRC or DBC selected by a selector 55 is subtracted and an absolute value calculation section 61 calculates an absolute value of the result of subtraction. A comparator 65 compares the results of the absolute value calculation section 61 and the multiplier 48. The timing of the comparison result in time division obtained by the comparator 65 is adjusted by a register 67 and an AND gate 68 is used to AND an output of the register 67 and an output of a register 66. A detection signal CT denoting whether or not a specific color area is generated based on an output of a gate 68. Desired processing or the like is conducted for a specific color area by using the signal CT.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color area detection circuit and an image pickup apparatus using the same. Specifically, by setting the color area using the first color information x and the second color information y that are not affected by the brightness, and detecting whether the color area is within the range of the color area, the brightness is affected. The color area detection is performed without any need. Further, the coefficient supply circuit switches and supplies a coefficient for color correction calculation processing to the color correction circuit based on the color area detection result, and performs color correction according to each of a specific color area and an area different from this color area. Or
For example, the level control means selects a color image pickup signal within a specific color region and controls the output signal level of the image pickup element based on this color image pickup signal.

[0002]

2. Description of the Related Art Conventionally, an image pickup apparatus has a contour correction circuit incorporated therein for compensating for response deterioration of an image pickup element and for enhancing sharpness. In order to show, the degree of contour enhancement is suppressed in the flesh-colored part. in this way,
The process of suppressing the degree of contour enhancement in the skin-colored part is called skin tone detail processing.

Further, an analog color image pickup signal obtained from an image pickup device is once digitized, and the tone characteristic is corrected by color correction processing or gamma correction with respect to the digitized image pickup signal. The correction is also performed so that an optimum contrast can be obtained when a high-luminance subject is imaged. Furthermore, the signal level of the image pickup signal corresponding to the entire image pickup screen or a predetermined position on the image pickup screen is detected, and, for example, the iris is driven based on the detected signal level, and the amount of incident light supplied to the image pickup element is changed. It is automatically controlled.

[0004]

In the skin tone detail processing, as shown in FIG. 6, the color difference signal R-
By adding Y and BY, and changing the addition ratio, hue φU,
While φL is determined, the addition output is input to the comparison circuit and compared with the reference voltage, and a gate signal indicating whether or not a desired color area AR indicated by the diagonal lines in the drawing, for example, a skin color portion is generated. It is a thing. In this way, the color region is detected using the color difference signals RY and BY whose signal levels are changed by the luminance signal Y. Therefore, the amount of incident light supplied to the image pickup device is automatically controlled based on the signal level of the image pickup signal corresponding to the entire image pickup screen or a predetermined position on the image pickup screen to change the background brightness or the subject. When the position of is changed and the brightness of the desired subject is changed against the intention of the photographer, the signal level of the color difference signals RY and BY is changed due to the change of the brightness level, and the skin color part Cannot be detected correctly.

In the color correction processing, for example, when desired color reproducibility is obtained by linear matrix processing, if a desired subject is adjusted to have a desired color, the colors of other subjects for which color adjustment is unnecessary are also combined. It will be changed. Therefore, the color of the desired subject can be corrected only within the range in which the change of the color of the other subject is allowable, and the color of the desired subject cannot be adjusted to the optimum state.

Therefore, the present invention provides a color area detection circuit which can detect a specific color area with a simple structure and high accuracy, and an image pickup apparatus which can easily obtain a photographed image desired by a photographer using the color area detection circuit. It is a thing.

[0007]

In order to solve the above-mentioned problems, a color area detection circuit according to the present invention determines a color area by using first color information x and second color information y which are not influenced by luminance. It has area setting means for setting and detection signal generating means for generating a detection signal by detecting whether or not it is within the range of the color area. The first color information x and the second color information y use a luminance signal W, a red signal R, and a blue signal B,
It is set as “x = (RW) / W” and “y = (BW) / W”.

In the area setting means, the first color information x
Reference color x0, the reference color y0 of the second color information y, the detection threshold value xth indicating the area range of the first color information x, and the detection threshold indicating the area range of the second color information y. Set the value yth,
The detection signal generating means multiplies the reference color x0, y0, the detection threshold values xth, yth, the first color information x, and the second color information by the luminance signal W,

[0009]

[Equation 2]

The detection signal is generated based on whether or not the condition (3) is satisfied.

Further, the detection signal generating means detects whether or not it is within the area range of the first color information x and the second color information y.
Detection is performed on a time-division basis to determine whether it is within the area range of
The detection signal is generated based on the detection result for the color information x and the second color information y.

In the image pickup apparatus according to the present invention, the area setting means for setting the color area using the first color information x and the second color information y which are not influenced by the brightness, and whether the area is within the range of the color area or not. And a detail signal generation means for generating a detail signal for correcting a captured image, and based on the detection signal generated by the detection signal generation means. The signal level of the detail signal generated by the detail signal generating means is changed.

Further, the color correction circuit has a color correction circuit for performing color correction on the color image pickup signal and a coefficient supply circuit for supplying a coefficient used in a color correction calculation process in the color correction circuit. The coefficient is switched based on the detection signal generated by the generation means and supplied to the color correction circuit.

Further, there is provided level control means for controlling the output signal level of the image pickup device based on the color image pickup signal,
The level control means selects a color image pickup signal based on the detection signal generated by the detection signal generation means, and controls the output signal level of the image pickup element based on the selected color image pickup signal.

According to the present invention, the color area is set by using the first color information x and the second color information y which are not influenced by the brightness, and the detection signal indicating whether or not the color area is within the range of this color area is set. Is generated, the color region can be detected without being affected by the luminance. Moreover, in the imaging device,
It is possible to perform desired skin tone detail processing, color correction processing, and the like on a specific color region without being affected by luminance.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail with reference to the drawings. FIG. 1 shows the structure of a video camera. In this video camera, the incident light is reflected by the lens 10
And the color separation prism 12 via the iris 11. In the color separation prism 12, the incident light is split into a red light ray, a green light ray, and a blue light ray, which are supplied to image pickup devices (hereinafter CCD image sensors) 13R, 13G, 13B, from which three primary color signals are obtained as color image pickup signals. It is designed to be done. By this lens 10, an optical image of the subject is formed on the image pickup surfaces of the CCD image sensors 13R, 13G, 13B. Also, by iris 11, CC
The amount of light to the D image sensors 13R, 13G, 13B is controlled.

CCD image sensor 13R, 13G, 1
The image pickup signals SR, SG, SB obtained from 3B are supplied to the A / D converters 15R, 15G, 15B via the analog process circuits 14R, 14G, 14B, respectively.

Analog process circuits 14R, 14G, 1
In 4B, level control such as white balance and black balance and defect correction are performed. In addition, the A / D converters 15R and 15
In G and 15B, the analog image pickup signal is the clock signal CK1 of the first sampling frequency (for example, 18 MHz).
Digitized by the three primary color imaging signals DR, D
G and DB. These three primary color imaging signals DR, DG, D
B is supplied to the image enhancer 20 and the control unit 25.

The red image pickup signal DR is delayed by the delay unit 30R for one horizontal scanning period and supplied to the image enhancer 20 as a red image pickup signal DR1H. Further, the red image pickup signal DR1H is further delayed by one horizontal scanning period in the delay section 31R and supplied to the image enhancer 20 as the red image pickup signal DR2H.

Similarly, the green image pickup signal DG is output to the delay unit 30G.
Then, it is delayed by one horizontal scanning period and supplied to the image enhancer 20 as a green image pickup signal DG1H. Further, the green image pickup signal DG1H is further delayed by one horizontal scanning period by the delay unit 31G and supplied to the image enhancer 20 as the green image pickup signal DG2H. In addition, the blue image pickup signal DB
Are supplied to the image enhancer 20 and the controller 25.

Further, the blue image pickup signal DB, the red image pickup signal DR1H and the green image pickup signal DG1H whose image positions correspond to the blue image pickup signal DB are filtered by the filter units 32R, 32G, 32.
B.

In the image enhancer 20, the red image pickup signals DR, DR1H, DR2H, the green image pickup signals DG, DG1H,
The detail signals Da and Db for enhancing the contour portion of the image are generated using DG2H and the blue image pickup signal DB, and the detail signal Da is generated based on the color area detection signal CT from the color area detection circuit 40 described later. , Db signal levels are controlled.

The filter section 32R and the filter section 32B are composed of a delay element and a low-pass filter, and the digital red image pickup signal and blue digital image pickup signal delayed by the delay element for a predetermined time are supplied to the up converters 35R and 35B. . The digital red image pickup signal and the blue image pickup signal whose band is limited by the low-pass filter are the red image pickup signal DRC.
And a blue image pickup signal DBC is supplied to the color region detection circuit 40.

The filter unit 32G is composed of a delay element and an interpolation filter, and the digital green image pickup signal delayed by the delay element for a predetermined time is supplied to the up converter 35G. In addition, the red image signal D
The green image pickup signal DGC, which is in phase with RC and the blue image pickup signal DBC, is supplied to the color region detection circuit 40.

Up converters 35R, 35G, 35B
Then, the digital three-primary-color imaging signals from the filter units 32R, 32G, and 32B are converted into A / D converters 15R and 15
The signal is converted (up-converted) based on a clock signal CK2 having a frequency (36 MHz) that is sufficiently higher than the first sampling frequency fs for G and 15B, and is supplied to the linear matrix circuit 85.

In the color area detection circuit 40, the filter section 32
Three primary color imaging signals DRC, DG from R, 32G, 32B
Whether or not it is a specific color area is detected based on C and DBC. Here, a method of detecting a color area will be described.

When the input signal is (R, G, B), the luminance signal W (the signal before the non-linear processing such as γ correction) is expressed by the equation 1. Further, it is known that (x, y) represented by (x) and (y) calculated by Equations 2 and 3 is an amount having information of only color.

[0028]

(Equation 3)

Here, as shown in FIG. 2, when the reference color (x0, y0) and the detection threshold values (xth), (yth) for detecting whether or not it is a specific color area are set, ( When x) satisfies the equation 4 and (y) satisfies the equation 5, the range of the specific color region, that is, the position (x0 + xth, y0 + yt
h), (x0 + xth, y0-yth), (x0-xth, y
It is possible to detect the range surrounded by (0-yth) and (x0-xth, y0 + yth).

[0030]

(Equation 4)

By substituting Equations 4 and 5 into Equations 2 and 3, Equations 6 and 7 can be obtained. In Expressions 6 and 7, it is possible to detect whether or not it is within the range of a specific color area without performing division, so that the color area detection process can be easily performed.

[0032]

(Equation 5)

Further, by rearranging the terms of Expressions 6 and 7, Expressions 8 and 9 can be obtained.

[0034]

(Equation 6)

Since the formula 10 and the formula 11 are established for the reference color (x0, y0), (x0 + 1) and (y0)
Since +1) is a positive value and it is not necessary to add a sign bit indicating a positive value or a negative value to the data, the arithmetic processing can be simplified.

[0036]

(Equation 7)

Further, (x0 + 1) in the equation 8 is replaced by (y0 + 1)
Then, by replacing (xth) with (yth) and (R) with (B), it becomes equal to the expression 9, so (x0 + 1) and (y0 + 1), (xth) and (yth), (R) By time-division-multiplexing (B) and (B), it is possible to perform arithmetic processing with a small-scale circuit.

FIG. 2 shows the configuration of the color area detection circuit 40 using the above-described color area detection method.

In FIG. 2, the phase-matched three primary color image pickup signals DRC, DGC, DBC are supplied to the W matrix section 41. The red image pickup signal DRC and the blue image pickup signal DBC are supplied to the selector 55 described later.

In the W matrix section 41, the processing of equation 1 is performed. The luminance signal W calculated based on Expression 1 is supplied to the multipliers 47 and 48 as the luminance signal WU via the clipping unit 42 and the register 43. The register 43 and the registers 50 to 53, 56 to 58, 66 described later are
The register 69 is driven based on the clock signal CK1 while being driven based on the clock signal CK2.

The control unit 25 shown in FIG. 1 has an integrating circuit, and the three primary color image pickup signals DR and D of an area designated by the object are provided.
G and DB are integrated to calculate integrated values RS, GS and BS. The brightness integrated value WS is calculated from the integrated values RS, GS, and BS calculated here based on Expression 12, and
From the brightness integrated value WS and the integrated values RS and GS, equations 13 and 1
Based on 4, the reference colors (x0 + 1) and (y0 + 1) are calculated.

[0042]

(Equation 8)

As described above, the control unit 2 which is the area setting means.
The reference colors (x0 + 1) and (y0 + 1) calculated in 5 are supplied to the selector 44. The control unit 25 sets detection thresholds (xth) and (yth) and supplies them to the selector 45. The detection thresholds (xth) and (yth) are variable so that color region detection is performed most favorably.

The selection signal generator 46 has two clock signals CK1 and CK1 from a signal generator (not shown).
The clock signal CK2 having a frequency doubled is supplied, and the selector control signal SE is generated based on the clock signals CK1 and CK2. This selector control signal SE is
It is supplied to the selectors 44 and 45 and the selector 55.

In the selectors 44 and 45, the reference colors (x0 +
1) and the detection threshold value (xth) are selected, or the selectors 44 and 45 select the reference color (y0 + 1) and the detection threshold value (yth). Selected standard color (x0 + 1)
Alternatively, the reference color (y0 + 1) is supplied to the multiplier 47. The selected detection threshold value (xth) or the detection threshold value (yth) is supplied to the multiplier 48.

In the multiplier 47, the reference color (x0 + 1) is multiplied by the luminance signal WU, or the reference color (y0 + 1) is multiplied by the luminance signal WU, and the data signal indicating the multiplication result is passed through the registers 50 and 51. And is supplied to the subtractor 60 as a data signal DMR.

In the multiplier 48, the detection threshold value (xth) is multiplied by the luminance signal WU, or the detection threshold value (yt
h) is multiplied by the luminance signal WU, and the data signal indicating the multiplication result is supplied to the comparator 65 as the data signal DMT via the registers 52 and 53.

In the selector 55, based on the selector control signal SE from the selection signal generator 46, the selectors 44, 4
When the reference color (x0 + 1) and the detection threshold value (xth) are selected in 5, the red image pickup signal DRC is selected. Further, when the reference color (y0 + 1) and the detection threshold value (yth) are selected by the selectors 44 and 45, the blue image pickup signal DB
C is selected. The red image pickup signal DRC or the blue image pickup signal DBC selected by the selector 55 is supplied to the subtractor 60 as the selected color data signal DRB via the registers 56, 57 and 58.

The subtractor 60 subtracts the selected color data signal DRB from the data signal DMR and supplies the subtraction signal DSB to the absolute value calculating section 61. That is, the subtractor 60
Then, (W (x0 + 1) -DRc) or (W (y0 +
1) -DBc) is calculated, and the calculation result is supplied to the absolute value calculation unit 61 as the subtraction signal DSB.

In the absolute value calculation unit 61, the subtraction signal DS
The absolute value of B is calculated, and the absolute value signal DAB corresponding to the calculation result on the left side of Expression 8 or Expression 9 is output to the comparator 65.
Is supplied to.

In the comparator 65, the absolute value signal DAB
And the data signal DMT are compared. Here, when the absolute value signal DAB indicates the absolute value of the operation result of (W (x0 + 1) -DRc), the data signal DMT indicates the multiplication result of the detection threshold value (xth) and the luminance signal WU. . In addition, the absolute value signal DAB is (W (y0 + 1) -DB
When the absolute value of the calculation result of c) is shown, the data signal D
MT indicates the multiplication result of the detection threshold value (yth) and the luminance signal WU. Therefore, the comparison signal indicating the comparison result of the comparator 65 is a signal indicating whether Expression 8 or Expression 9 is satisfied.

The comparison signal output from the comparator 65 is supplied to the AND gate 68 as the signal CMA via the register 66, and the signal CMB via the register 67 and the register 67 driven based on the selector control signal SE. Is supplied to the AND gate 68. Here, the signal level of the signal CMA is high level “H” when it is within the range of the specific color region, and the signal level of the signal CMA is low level “L” when it is not within the range of the specific color region. . The output signal of the AND gate 68 is
A register 7 driven as a signal CMC via the register 69 and further based on the clock signal CK1
The color region detection signal CT is obtained by passing through 0, and as shown in FIG.
And the coefficient supply circuit 80.

Next, the color area detection circuit 40 will be described with reference to FIG.
The operation of will be described. FIG. 3A shows the clock signal CK1 supplied to the selection signal generator 46 shown in FIG.
FIG. 3B shows the clock signal CK2. Based on the clock signals CK1 and CK2, the selector control signal S shown in FIG.
E is generated. This selector signal SE is the trailing edge of the signal level of the clock signal CK2 (hereinafter "negative edge").
Signal) whose signal level is inverted in synchronism with.

FIG. 3D shows the filter units 32R, 32G and 32.
Three primary color imaging signals DRC, DGC, DBC supplied from B
Is shown. These three primary color imaging signals DRC, DGC, DB
Based on C, the W matrix unit 41 shown in FIG.
The luminance signal W shown in is generated. For example, when the data values of the three primary color image pickup signals DRC, DGC, DBC are "r0, g0, b0", the data value of the luminance signal W is "w0",
The data values of the three primary color imaging signals DRC, DGC, DBC are "r
When it is "1, g1, b1", the data value of the luminance signal W is "w1". As the brightness signal W, the data value of the brightness signal W is temporarily stored by the register 43 at the timing of the negative edge of the clock signal CK2, and becomes the brightness signal WU shown in FIG. 3F.

Here, when the signal level of the selector control signal SE is set to the high level "H", the selector 44 selects the reference color (x0 + 1) as shown in FIG. 3G, and as shown in FIG. 3H. The detection threshold value (xth) is selected by the selector 45. Further, when the signal level is low level “L”, the selector 44 causes the reference color (y
0 + 1) is selected, and the selector 45 selects the detection threshold value (yth).

The multiplier 47 multiplies the reference color (x0 + 1) or the reference color (y0 + 1) by the luminance signal WU. This multiplication result is passed through the registers 50 and 51 to the subtractor 60.
Is supplied to. Therefore, the data signal DMR supplied to the subtractor 60 is the clock signal CK2 as shown in FIG. 3J.
Are delayed by two cycles and are supplied to the subtractor 60.

In the selector 55, the red image pickup signal DRC is selected when the signal level of the selector control signal SE is high level "H", and the blue image pickup signal DBC is selected when it is low level "L". It The selected image pickup signal is supplied to the subtractor 60 via the registers 56, 57 and 58. Therefore, the subtraction signal DSB indicating the subtraction result in the subtractor 60 is as shown in FIG. 3K. The subtraction signal DSB is supplied to the absolute value calculation unit 61 and the absolute value is calculated. The absolute value signal DAB indicating the calculation result of the absolute value calculation unit 61 is supplied to the comparator 65.

In the multiplier 48, the detection threshold value (xth) or the detection threshold value (yth) selected by the selector 45 as shown in FIG. 3H is multiplied by the luminance signal WU shown in FIG. 3F. The multiplication result is supplied to the comparator 65 via the registers 52 and 53. Therefore, the data signal DMT supplied to the comparator 65 is delayed by two cycles of the clock signal CK2 and supplied to the comparator 65, as shown in FIG. 3L.

In this comparator 65, the absolute value signal D
AB and the data signal DMT are compared to each other, and a comparison signal indicating a comparison result, that is, it is detected whether Expressions 8 and 9 are satisfied, and a signal indicating a detection result is generated. The comparison signal indicating the detection result is supplied to the AND gate 68 via the register 66 as the signal CMA as shown in FIG. 3M, and also as the signal CMB as shown in FIG. 3N via the registers 66 and 67. 68.

Therefore, the output signal output from the AND gate 68 via the register 69 becomes the signal CMC shown in FIG. 3P via the register 69. Further, through the register 70 driven by the clock signal CK1, only data correctly indicating whether or not the color region is a specific color region is selected, and the color region detection signal CT is displayed as shown in FIG. 3Q.
It is said.

If a comparator having a hysteresis characteristic is used as the comparator 65, the comparison result may be changed by a slight fluctuation of the signal level of the absolute value signal DAB or the data signal DMT or noise. This can be prevented, and the color area can be detected stably.

In this way, the color area detection signal CT obtained by the color area detection circuit 40 is the image enhancer 20.
Are supplied to the control unit 25 and the coefficient supply circuit 80.

The image enhancer 20 controls the signal levels of the detail signals Da and Db based on the color area detection signal CT. For example, when a flesh color area is detected, the signal levels of the detail signals Da and Db are set to be low, and it is possible to prevent the rough skin and the like from being emphasized.

From the coefficient supply circuit 80 to the linear matrix circuit 85, the coefficient a used in the linear matrix calculation processing is
To f are supplied, and the coefficient values of the coefficients a to f are switched based on the color region detection signal CT.

Here, FIG. 4 shows the configuration of the coefficient supply circuit 80. Two reference values A (1) and A (2) for calculating the coefficient a are preset in the coefficient supply circuit 80, and the coefficient a is calculated based on the color area detection signal CT.
It is variable within the range of (1) to A (2). Also, coefficient b
Similarly for f, there are two reference values B (1), B (2), C (1), C (2), D for each coefficient.
(1), D (2), E (1), E (2), F (1), F
(2) is preset, and the coefficients b to f are the reference values B (1) to B based on the color region detection signal CT.
(2), C (1) to C (2), D (1) to D (2), E
It is variable within the range of (1) to E (2) and F (1) to F (2).

The reference values A (1), A (2), ...
The value of F (2) is, for example, as shown in FIG.
Are reference values A (1), B (1), ..., F, respectively.
When the value is made equal to (1), the detected color area is subjected to the same color correction as other color areas, and the coefficients a to f are set to the reference values A (2), B (2) ,. , F (2), the detected color area is color-corrected differently from the other color areas, for example, the color is corrected to a tan skin color.

Here, the reference value A (1) is supplied to the subtractor 81a and the adder 82a as shown in FIG. Further, the reference value A (2) is supplied to the subtractor 81a. This subtractor 8
In 1a, the reference value A (1) is subtracted from the reference value A (2), and the subtraction value AS is supplied to the multiplier 83a. Multiplier 8
3a is supplied with a multiplication coefficient MK generated based on the color area detection signal CT from a low-pass filter section 84 described later, and this multiplication coefficient MK is multiplied by the subtraction value AS supplied from the subtractor 81a. Then, the obtained multiplication value ASM is supplied to the adder 82a and added to the reference value A (1) to calculate the coefficient a.

That is, the subtraction 81a, the adder 82a, and the multiplier 83a are used to perform the operation of Expression 15, and the coefficient a is calculated from the reference values A (1), A (2) and the multiplication coefficient MK. a = ASM + A (1) = MK × AS + A (1) = MK {A (2) -A (1)} + A (1) (Equation 15)

The low-pass filter section 84 has a low-pass filter composed of, for example, an FIR filter, and the supplied digital color region detection signal CT is processed by the low-pass filter to smoothly change the signal level. It is supposed to be. Next, the coefficient value of the multiplication coefficient MK is “0” to “1” according to the signal level of the color region detection signal CT after the filter processing.
Is set in the range. Here, since the change in the signal level of the color area detection signal CT is smooth, the change in the coefficient value of the multiplication coefficient MK is also smooth.

When setting the coefficient value of the multiplication coefficient MK, the signal level of the processed color area detection signal CT is weighted. For example, when the signal level of the color region detection signal CT after the filter processing is low, the coefficient value of the multiplication coefficient MK is set to a small value, and the coefficient value of the multiplication coefficient MK changes with respect to the change of the signal level. It is supposed to be small. When the signal level is high, the multiplication coefficient M
The coefficient value of K is set to a large value, and the change of the coefficient value of the multiplication coefficient MK with respect to the change of the signal level is large.

In this way, the coefficient value of the multiplication coefficient MK changes smoothly, and the signal level of the processed color area detection signal CT is weighted to set the coefficient value of the multiplication coefficient MK. Therefore, the coefficient value of the coefficient a calculated by the equation 15 using the multiplication coefficient MK also has a smooth change and is a value weighted based on the color region detection signal CT. . Although not described, the coefficient values of the coefficients b to f are set similarly to the coefficient value of the coefficient a.

Therefore, it is possible to prevent the coefficient values of the coefficients a to f from being frequently switched and to prevent the image quality from being deteriorated, and, for example, when the continuous amount of the area detected as the skin color area is large, that is, When the flesh color area is large, the color of the detected flesh color area is corrected to a smooth tan color, and when the continuous amount of the area detected as the flesh color area is small, that is, when the flesh color area is small, it is detected. The color of the skin color region is smoothly color-corrected to a skin color like a slight sunburn, and a smooth image having good image quality and no discomfort can be obtained.

The reference values A (1) to F shown in FIG.
The value of (2) is an example, and the reference values A (1) to F (2) are used.
By changing the value of, for example, it is possible to easily correct not only the tanned skin color in the area detected as the skin color area but also another color.

In the linear matrix circuit 85, timing adjustment is performed by delaying for a predetermined time by the filter units 32R, 32G, 32B, and the three primary color data signals DRU up-converted and supplied by the up converters 35R, 35G, 35B. , DGU, D
Color correction is performed by a linear matrix calculation process using BU and the coefficients a to f supplied from the coefficient supply circuit 80. Since the coefficients a to f are switched based on the color area detection signal CT, different color correction can be performed in the detected specific color area and other color areas. Therefore, for example, only the skin color can be adjusted without affecting the colors of other areas.

The three primary color data signals DRUC, DGUC, DBUC obtained by the linear matrix circuit 85 are the knee correction circuit 9
0R, 90G, 90B through addition units 91R, 91G,
Supplied to 91B.

The detail signal Db generated by the image enhancer 20 is supplied to the adders 91R, 91G and 91B.
The three primary color data signals DRUC, DGUC, DBUC and the detail signal Db are respectively added, and the added signals are added through the γ correction circuits 92R, 92G, 92B, and the addition units 93R, 93 are provided.
G, 93B.

The detail signal Da generated by the image enhancer 20 is supplied to the adders 93R, 93G and 93B.
The addition signal supplied via the γ correction circuits 92R, 92G, 92B and the detail signal Da are added, and the signal level of the addition signal supplied via the γ correction circuits 92R, 92G, 92B is controlled. This adder 93R, 93
The addition signal obtained by G and 93B is the clipping circuit 94.
Y / C matrix circuit 95 via R, 94G, 94B
Is supplied to.

In the Y / C matrix circuit 95, the luminance signal Y and the color difference signals Cr, Cb are generated based on the addition signals supplied via the clip circuits 94R, 94G, 94B, and are generated via the clip circuits 96Y, 96RY, 96BY. Is output. Also, a luminance signal YVF for the viewfinder is generated and supplied to a viewfinder device (not shown) via the clip circuit 96YV.

Color area detection signal C from color area detection circuit 40
The control unit 25 supplied with T selects the three primary color image pickup signals DR, DG, and DB when it is detected that the color region is a specific color region based on the color region detection signal CT, and selects the selected three primary color image pickup signal DR. , DG, and DB, an iris control signal IRC is generated and supplied to the iris driving unit 100. Alternatively, the shutter control signal SHC is generated and supplied to the sensor driving unit 16.

In the iris driving section 100, the iris driving signal IRD is generated based on the iris control signal IRC to drive the iris 11. Therefore, for example, it is possible to perform control so that the amount of light is optimal in the skin color region.
In the image sensor drive unit 16, the image sensor drive signal RV is controlled based on the shutter control signal SHC to control the charge accumulation time in the CCD image sensors 13R, 13G, 13B, that is, the shutter speed of the electronic shutter is changed. As a result, an image pickup signal of a desired level can be obtained. Instead of the iris 11 and the electronic shutter, an ND (neutral density) filter or the like which is composed of liquid crystal or two polarizing filters and which can adjust the light reduction amount may be used.

As described above, according to the above-described embodiment,
A luminance signal W is obtained from the three primary color image pickup signals DRC, DGC, and DBC, and the reference signal W, the red image pickup signal DRC, and the blue image pickup signal DBC, and a reference color (x0
+1), (y0 + 1) and detection thresholds (xth), (yt
Since color area detection can be performed using h) without being affected by brightness, stable color area detection can be performed even when the brightness of the subject changes due to illumination or the aperture of the imaging device. it can. Further, since the color area detection is performed based on only the color information without being influenced by the brightness, the color area detection can be performed with high accuracy.

In this color region detection, the red image pickup signal DRC and the reference color (x0 + 1) and the detection threshold value (xth) or the blue image pickup signal DBC and the reference color (y0 + 1) and the detection threshold value (yth) are time-divided. Since the color area detection circuit 40 is selected by (1) and executed without including the division processing, the circuit scale of the color area detection circuit 40 can be reduced.

Further, a specific color area is detected by the color area detection circuit 40, the coefficient supply circuit 80 is controlled based on the detection signal CT indicating the detection result, and the linear matrix calculation processing in the linear matrix circuit 85 is performed. The coefficients used are automatically switched. Therefore, the coefficient for the specific color area and the coefficient for the area different from this color area can be set to different values, and thus the color correction according to the specific color area and the area different from this color area can be automatically switched. ,
For example, the skin color and background color of a person can be adjusted separately.

Further, based on the detection signal CT from the color area detection circuit 40, the control section 25 selects an image pickup signal of a specific color area, and the shutter speed of the iris 11 and the electronic shutter is changed based on the selected image pickup signal. Since it is automatically controlled, the subject can be photographed at a desired brightness without being affected by the fluctuation of the background brightness.

In the above embodiment, the luminance signal W
Although the specific color region is detected with high accuracy using (the signal before the non-linear processing such as γ correction), if the detection accuracy is at an allowable level, the luminance that has been subjected to the non-linear processing such as γ correction The detection process can be performed using the signal Y or the like.

[0086]

As described above, according to the present invention, the color area is set by using the first color information x and the second color information y which are not influenced by the luminance, and within the range of this color area. Since the detection signal indicating whether or not there is is generated, the color region is detected without being affected by the brightness. This color region detection processing is performed without including division, and detection of the first color information x and the second color information y is performed in a time division manner.

Therefore, even if the brightness of the subject changes due to changes in the illumination conditions, the diaphragm, etc., the color area can be detected stably. Further, since the color area detection is performed based on only the color information, the color area detection can be performed with high accuracy. Furthermore, since the color area detection processing does not include division and is performed in a time-division manner, it is possible to reduce the circuit scale of the color area detection circuit.

Further, since the image pickup device can detect a specific color region without being affected by the luminance and automatically switch the coefficient for color correction calculation processing supplied to the color correction circuit, If a coefficient for a color area and a coefficient for an area different from this color area are set in advance, it is possible to automatically switch color correction according to a specific color area and an area different from this color area. It is possible to separately adjust the skin color and the background color, and more aggressive image creation can be performed. Furthermore, since a specific color area is detected and the shutter speed of, for example, an aperture or an electronic shutter is automatically controlled in accordance with this color area, a desired object can be obtained without being affected by fluctuations in background brightness. You can shoot in the brightness.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of an imaging device.

FIG. 2 is a diagram showing a configuration of a color area detection circuit 40.

FIG. 3 is a diagram showing an operation of a color area detection circuit 40.

FIG. 4 is a diagram showing a configuration of a coefficient supply circuit 80.

FIG. 5 is a diagram showing reference values.

FIG. 6 is a diagram for explaining a conventional color area detection operation.

[Explanation of Codes] 11 ... Iris, 13R, 13G, 13B ... C
CD image sensor, 16 ... Sensor drive unit, 20 ...
..Image enhancers, 25 ... Control unit, 32R,
32G, 32B ... Filter section, 40 ... Color area detection circuit, 41 ... W matrix section, 44, 45, 55
... Selector, 46 ... Selection signal generator, 47,4
8 ... Multiplier, 60 ... Subtractor, 61 ... Absolute value calculation unit, 65 ... Comparator, 80 ... Coefficient supply circuit, 84 ... Low-pass filter unit, 85 ... Linear matrix circuit

Claims (12)

[Claims] 1. A region setting means for setting a color region using first color information x and second color information y which are not influenced by luminance, and whether or not an input signal is within the range of the color region. A color region detection circuit having a detection signal generating means for detecting and generating a detection signal. 2. A luminance signal W, a red signal R, and a blue signal B are used, the first color information x is x = (RW) / W, and the second color information y is y = (B-W). ) / W 2 is set as the color area detection circuit. 3. The area setting means includes a reference color x0 of the first color information x and a reference color y0 of the second color information y.
And a detection threshold value xth indicating the area range of the first color information x and a detection threshold value yth indicating the area range of the second color information y are set. The reference color x0, y0, the detection threshold values xth, yth, the first color information x, and the second color information are multiplied by the luminance signal W, and 3. The color area detection circuit according to claim 2, wherein the detection signal is generated based on whether or not the condition of is satisfied. 4. The detection signal generating means detects whether it is within the area range of the first color information x and whether it is within the area range of the second color information y. 2. The color region detection circuit according to claim 1, wherein the detection signal is generated based on a detection result for the first color information x and the second color information y. 5. Area setting means for setting a color area using the first color information x and the second color information y which are not influenced by luminance, and whether or not the color image pickup signal is within the range of the color area. And a detail signal generating means for generating a detail signal for correcting the photographed image, and based on the detection signal generated by the detection signal generating means. The image pickup apparatus is characterized in that the signal level of the detail signal generated by the detail signal generating means is varied. 6. The image forming apparatus further comprises video signal generating means for performing signal processing including nonlinear level conversion on the color image pickup signal to generate a video signal, and the first color information x and the first color information used in the area setting means. The color information y of 2 includes a luminance signal W generated based on the color image pickup signal and a red image pickup signal R of the color image pickup signal.
And the blue image pickup signal B, the first color information x = (RW) / W and the second color information y = (BW) / W are set and generated by the video signal generating means. The image pickup apparatus according to claim 5, wherein the video signal includes a luminance signal Y. 7. Area setting means for setting a color area using the first color information x and the second color information y which are not affected by luminance, and whether or not the color image pickup signal is within the range of the color area. Detection signal generating means for detecting a color and a detection signal, color correction means for performing color correction on the color image pickup signal, and coefficient supply for supplying coefficients used in color correction calculation processing by the color correction means. An image pickup apparatus comprising means, wherein the coefficient supplying means switches the coefficient on the basis of the detection signal generated by the detection signal generating means and supplies the coefficient to the color correcting means. 8. The first color information x and the second color information y used in the area setting means are a luminance signal W generated based on the color image pickup signal and a red image pickup signal of the color image pickup signal. The color information is set as the first color information x = (RW) / W second color information y = (BW) / W by using R and the blue image pickup signal B. Imaging device. 9. An area setting means for setting a color area using the first color information x and the second color information y which are not influenced by brightness, and whether or not the color image pickup signal is within the range of the color area. And a level control means for controlling the output signal level of the image pickup device based on the color image pickup signal. The level control means includes the detection signal generation means. An image pickup apparatus, characterized in that the color image pickup signal is selected based on the detection signal generated in (3), and the output signal level of the image pickup element is controlled based on the selected color image pickup signal. 10. The first color information x and the second color information y used in the area setting means are a luminance signal W generated based on the color image pickup signal and a red image pickup signal of the color image pickup signal. 10. The color information is set as the first color information x = (RW) / W second color information y = (BW) / W using R and the blue image pickup signal B. Imaging device. 11. The level control means has an iris for controlling the amount of incident light incident on the image pickup device, and controls the iris based on the selected color image pickup signal to output the image pickup device. The image pickup apparatus according to claim 9, wherein a signal level is controlled. 12. The level control means has an electronic shutter for varying the charge storage time of the image pickup device, and controls the electronic shutter based on the selected color image pickup signal to output the output signal level of the image pickup device. The image pickup apparatus according to claim 9, wherein the image pickup apparatus controls the image pickup apparatus.