JPH09200785A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device with which the correction quantity of a contour correct signal can be properly controlled without using any look-up table(LUT). SOLUTION: This image pickup device has an imaging device 101, A/D converter 102, color separator circuit 103, low-pass filters(LPF) 104-106, APC circuit 107, gain control circuit 108, chrominance signal detection circuit 109, adder circuits 110-112, gamma correction circuit 113 and encoder circuit 114. RGB chrominance signals outputted from the LPF 104, 105 and 106 are converted to luminance Y and color difference signals R-Y and B-Y by the encoder circuit at the chrominance signal detection circuit 109. The converted luminance/color difference signals are inputted to respective detection circuits, outputted as detecting signals after the execution of respective prescribed operations and inputted to a selection circuit. This selection circuit outputs a minimum value among the inputted signals as a final color detecting signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing the structure of a conventional image pickup apparatus. In the figure, 501 is an image sensor (CC
D), 502 is an A / D converter for digitizing the signal from the image sensor 501, 503 is a color separation circuit for separating a color signal from the signal obtained by the image sensor 501, 504 to
506 is a low pass filter (LPF).

Reference numeral 507 is an APC circuit for generating a contour correction signal, 508 is a gain control circuit for controlling the gain of the contour correction signal, 509 is a color signal detection circuit for detecting a color signal, 510 to 512 are addition circuits, and 513 is a gamma. The correction circuit 514 is an encoder circuit that generates a luminance / color difference signal from a color signal.

In the figure, the signal output from the image pickup device 501 is digitized by an A / D converter 502. The signal is processed by the color separation circuit 503 to obtain RGB signals.
Separated into color signals. The RGB color signals are band-limited by the low-pass filters 504 to 506 respectively, and then are input to the gamma correction circuit 513 through the addition circuits 510 to 512 to be gamma-corrected, and are converted into luminance / color difference signals by the encoder circuit 514 and output. To do.

On the way, the G (green) signal of the RGB color signals is taken out and input to the APC circuit 507, where a contour correction signal is created from the high frequency components of the G signal. The contour correction signal passes through the gain control circuit 508 and the adding circuit 51.
0 to 512 are added to the original RGB color signals to create a contour-corrected video signal.

The color filter attached to the image pickup device 501 is generally arranged so that the band of the G signal closest to the luminance signal can be sufficiently taken.
The original signal band is narrow for the (red) and B (blue) signals. Therefore, for example, when the gain of the contour correction signal is set in accordance with the R signal, the G signal is excessively corrected, and the screen becomes very unsightly.

Therefore, when controlling the contour correction signal, the color signal detection circuit 509 is used to detect a signal for increasing the correction amount of the contour correction signal from the RGB color signals, and the gain control circuit is based on the detected signal. 508 is controlled to keep the contour correction signal appropriate. The color signal detection circuit 509 is configured by a look-up table (LUT) method, and in this imaging device, the range of the color signal to be detected is written in the look-up table, and the color is detected from the input RGB color signal. It is configured to output a detection signal.

[0008]

However, the above-mentioned conventional image pickup device has a problem that the scale of the lookup table itself becomes large. This is not only a problem that the device becomes large as the circuit scale increases, but also a problem that a large amount of data must be transferred when it is necessary to rewrite the detection range of the color signal detection circuit. was there.

Therefore, an object of the present invention is to provide an image pickup apparatus capable of appropriately controlling the correction amount of the contour correction signal without using a look-up table.

[0010]

In order to achieve the above object, an image pickup apparatus according to claim 1 of the present invention comprises color signal extraction means for extracting a plurality of color signals from an output signal of the image pickup means, In an imaging device that corrects a contour correction signal with an extracted color signal, a calculating unit that calculates the plurality of extracted color signals, and a predetermined color detection signal on a color space according to the calculated color signal The detection means for detecting, and the correction amount control means for controlling the correction amount of the contour correction signal based on the detected color detection signal, the calculation means, from each of the plurality of extracted color signals Obtaining a plane on the color space, limiting each obtained plane by a predetermined value,
The detection means extracts the minimum value of all the limited planes and uses it as a color detection signal.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of an image pickup apparatus of the present invention will be described. FIG. 1 is a block diagram showing the configuration of the image pickup apparatus according to the embodiment.

In the figure, 101 is an image sensor (CC
D), 102 is an A / D converter for digitizing the signal from the image sensor 101, 103 is a color separation circuit for separating a color signal from the signal obtained by the image sensor 101, 104 to
Reference numeral 106 is a low pass filter (LPF). Reference numeral 107 denotes an APC circuit for generating a contour correction signal, 108 denotes a gain control circuit for controlling the gain of the contour correction signal, 10
9 is a color signal detection circuit for detecting a color detection signal, 110-1
Reference numeral 12 is an addition circuit, 113 is a gamma correction circuit, and 114 is an encoder circuit for generating a luminance / color difference signal from a color signal.

In the figure, the signal output from the image pickup device 101 is digitized by an A / D converter 102. The signal is processed by the color separation circuit 103 and RGB
Separated into color signals. The RGB color signals are band-limited by the low-pass filters 104 to 106 respectively, and then are input to the gamma correction circuit 113 through the addition circuits 110 to 112 to be gamma-corrected, and are converted into luminance / color difference signals by the encoder circuit 114 and output. To do.

On the way, the G (green) signal of the RGB color signals is taken out and input to the APC circuit 107, where a contour correction signal is created from the high frequency components of the G signal. The contour correction signal passes through the gain control circuit 108 and the adding circuit 11
0 to 112 is added to the original RGB color signal to create a contour-corrected video signal.

FIG. 2 is an explanatory view showing a color filter attached to the image pickup device 101. The color filter is generally arranged so that the band of the G signal closest to the luminance signal can be sufficiently taken.

FIG. 3 is a block diagram showing the configuration of the color signal detection circuit 109. In the figure, 301 is an encoder circuit that produces luminance Y and color difference signals RY and BY from RGB color signals, 302 is a first hue detection circuit that calculates a first hue detection plane, and 303 is a second hue detection plane. Second to calculate
A hue detection circuit, 304 is a first saturation detection circuit that calculates a first saturation detection plane, and 305 is a second saturation detection circuit that calculates a second saturation detection plane.

Reference numeral 306 denotes a first brightness calculating plane for calculating the first brightness detection plane.
A luminance detection circuit, 307 is a second luminance detection circuit that calculates a second luminance detection plane, and 308 is a signal obtained by selecting from the first hue detection circuit 302 to the second luminance detection circuit 307, and outputs it as a color detection signal. It is a selection circuit.

In the color signal detection circuit 109 having the above structure, the RGB color signals output from the low pass filters 104, 105 and 106 are converted into the luminance Y and the color difference signals RY and BY in the encoder circuit 301. . The converted luminance / color difference signal is input to each of the detection circuits 302 to 307, subjected to a predetermined calculation, output as a detection signal, and input to the selection circuit 308. The selection circuit 308 outputs the smallest value from the input signals as the final color detection signal.

FIG. 4 is an explanatory diagram showing the structure of the color signal detection circuit 109 in detail. In the figure, reference numeral 301 is an encoder circuit for producing a luminance Y and color difference RY, BY signals from RGB color signals as described above. 402, 403, 40
5, 406 are multiplication circuits, 404, 407, 408 are switchers for switching constants K, +1 and -1 based on the coefficient FST.
409 is an addition circuit, 410 is a multiplication circuit, 411 is a limiter, 412, 413, 415, and 416 are multiplication circuits, 41
4, 417 and 418 are constants K, +1 and
A switch for switching −1, 419 is an adding circuit, 420 is a multiplying circuit, 421 is a limiter, and 422 and 423 are absolute value circuits.

Reference numerals 424, 425 and 426 denote adder circuits, and 42
7, 428 are multiplication circuits, 429, 430 are limiters, 4
31 and 432 are addition circuits, 433 and 434 are multiplication circuits,
435 and 436 are limiters. Reference numeral 308 is a selection circuit as described above, and is composed of a minimum value circuit.

In the color signal detection circuit 109, first, the coefficient FS
T, FRK, FED, FFK, DST, DRK, DE
D, DFK, LST, LRK, LED, and LFK detect the hue start and detection rising angle respectively, the hue end and detection falling angle detected, the saturation start and detection rising angle detected, and detected Set the saturation end and detected fall angle, the detected luminance start and detected rise angle, and the detected luminance end and detected fall angle.

The RGB color signal of the input image signal is processed by the encoder circuit 301 in the luminance signal Y and the color difference signals RY and B-.
Converted to Y, each signal is input to each detection circuit. Reference numerals 402 to 411 correspond to the first hue detection circuit 302 in FIG. The input color difference signals R-Y and B-
With respect to Y, +1 and -1 are switched by the switch 404 based on the coefficient FST, and the hues are rotated by 90 degrees by multiplication by the multipliers 402 and 403. Similarly, F
The coefficient K is switched by the switches 407 and 408 based on ST,
By multiplying by the multipliers 405 and 406, the hue can be rotated more finely. At this time, the value of the coefficient K is set to 0.
By setting the value up to 0.75 for every 0.25, it becomes possible to rotate every 22.5 degrees.
Together with 04, 360 degrees can be divided into 16 parts.

Thereafter, the obtained signals are added by the adder 409, and the detected rising angle FRK (for example, 0.5, 1,
2, 4, 8) is multiplied by the multiplication circuit 410, and the limiter 41
Set the upper limit (lim) at 1 and round down to 0,
The first hue detection signal is output.

Similarly, reference numerals 412 to 421 correspond to the second hue detection circuit 303 in FIG. 3, and the input color difference signal is switched to +1 or -1 based on the coefficient FED.
The hue is rotated by 90 degrees by switching at 14 and multiplying by the multipliers 412 and 413. Further, similarly, the coefficient F
The coefficient K is switched by the switches 417 and 418 based on ED,
The hues are rotated more finely by multiplying by the multipliers 415 and 416.

After that, the obtained signals are added by the adder 419, the detection rising angle FFK is multiplied by the multiplication circuit 420, and the limiter 421 sets the upper limit and rounds down to 0 or less, and outputs the second hue detection signal. To do.

Further, 422 to 424, 425, 427,
Reference numeral 429 corresponds to the first saturation detection circuit 304 in FIG. 3, and similarly 422 to 424, 426, 428, 43.
0 corresponds to the second saturation detection circuit 305 in FIG. Absolute value circuits 422 and 423 use respective color difference signals R
The absolute values of −Y and BY are taken and added by the adder circuit 424. The added signals are further added by adding circuits 425, 4
At 26, the coefficients DST and DED are added, and the coefficient D
The RK and DFK are multiplied by the multiplication circuits 427 and 428, respectively. Then, the limiters 429 and 430 set the upper limit and round down to 0 or less, and output the first saturation detection signal and the second saturation detection signal 2.

Reference numerals 431, 433 and 435 correspond to the first brightness detecting circuit 306 of FIG.
Reference numerals 434 and 436 correspond to the second luminance detection circuit 307 of FIG. 3, and the luminance signal Y is input to each.
The coefficients LST and LED are added by the adder circuits 431 and 432, and the coefficient LRK and LFK are further added.
Multiplied by 3,434. After that, the limiters 435, 4
At 36, the upper limit is set and the value is rounded down to 0 or less, and the first luminance detection signal and the second luminance detection signal are output.

FIG. 5 is an explanatory diagram showing each detection signal. The same figure (A) shows the output of the first hue detection signal, and the same figure (B) shows the second
Output of hue detection signal, output of first saturation detection signal in FIG. 6C, output of second saturation detection signal in FIG. 7D, output of first luminance detection signal in FIG. FIG. 6F shows the output of the second luminance detection signal. Each detection signal is input to the selection circuit 308 including a minimum value circuit, and the smallest value of the six signals is selected. The selected signal is sent to the gain control circuit 108 as a color detection signal.

[Other Embodiments] FIG. 6 is an explanatory diagram showing a configuration of a color signal detection circuit according to another embodiment. The difference from the above-described embodiment is that the encoder circuit 701 has R
RG instead of generating a luminance / color difference signal from a GB color signal
It is to generate G, RG, and BG signals from B color signals. The other circuits and their operation are the same.

[0030]

According to the image pickup device of the first aspect of the present invention, the color signal extraction means extracts a plurality of color signals from the output signal of the image pickup means, and the contour correction signal is corrected by the extracted color signals. In this case, the calculating means calculates the plurality of extracted color signals, the detecting means detects a predetermined color detection signal on the color space according to the calculated color signals, and the correction amount controlling means detects the predetermined color detection signal. The correction amount of the contour correction signal is controlled on the basis of the extracted color detection signal, but the calculating means obtains a plane on a color space from each of the extracted plurality of color signals, and the obtained plane Is limited by a predetermined value, and the detection means extracts the minimum value of all the limited planes as a color detection signal. Therefore, the plane in the color space is calculated from the color signal obtained by the image pickup means. , Combining each More predetermined color detection signal can be accurately detected. Therefore, the lookup table (LU
T) is unnecessary, the device can be downsized without increasing the circuit scale, and a large amount of data transfer is not required when changing the detection range of the color detection signal.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an imaging device according to an embodiment.

FIG. 2 is an explanatory diagram showing a color filter attached to an image sensor 101.

FIG. 3 is a block diagram showing a configuration of a color signal detection circuit 109.

FIG. 4 is an explanatory diagram showing a detailed configuration of a color signal detection circuit 109.

FIG. 5 is an explanatory diagram showing each detection signal.

FIG. 6 is an explanatory diagram showing a configuration of a color signal detection circuit according to another embodiment.

FIG. 7 is a block diagram showing a configuration of a conventional imaging device.

[Explanation of symbols]

 101 image sensor 103 color separation circuit 104 low-pass filter 107 APC circuit 108 gain control circuit 109 color signal detection circuit 110, 111, 112 adder circuit 301 encoder circuit 302 first hue detection circuit 303 second hue detection circuit 304 first saturation detection Circuit 305 Second chroma detection circuit 306 First luminance detection circuit 307 Second luminance detection circuit 308 Selection circuit

Claims (1)

[Claims] 1. An image pickup apparatus comprising color signal extraction means for extracting a plurality of color signals from an output signal of an image pickup means, and correcting a contour correction signal with the extracted color signals, wherein the plurality of extracted color signals are provided. Calculating means for calculating a predetermined color detection signal in the color space according to the calculated color signal, and a correction amount of the contour correction signal based on the detected color detection signal. Compensation amount control means for controlling, the computing means obtains a plane on a color space from each of the extracted plurality of color signals, limits each obtained plane by a predetermined value, the detecting means Is an image pickup apparatus, wherein the minimum value of all the limited planes is extracted and used as a color detection signal.