JP2001008218A - High luminance compression processing circuit and color television camera apparatus using circuit thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high luminance compression processing circuit where saturation of colors becomes smaller as the luminance is closer to its saturation and does not change a hue. SOLUTION: This high luminance compression processing circuit has high luminance compression circuits 1-3, that respectively compress a three primary color video signal to be a prescribed signal level or below and a means that multiplies a ratio resulting from dividing a 1st luminance signal through the matrix arithmetic operation of the video signal compressed by the high luminance compression circuits 1-3 by a 2nd luminance signal obtained through the matrix arithmetic operation of the 3 primary color video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-luminance compression processing circuit for further reducing a change in hue generated when a high-luminance video signal level is compressed, and further relates to a television camera device using the high-luminance compression processing circuit. .

[0002]

2. Description of the Related Art Conventionally, as a high luminance signal compression processing circuit for compressing a high luminance signal level of a video signal, high luminance signal compression processing is performed while maintaining the color difference levels of three primary color signals before high luminance compression. Some of them operate so that the saturation of the color signal at high luminance is increased and the color is over-applied.

A conventional high-luminance signal compression processing circuit and a television camera using the circuit will be described below with reference to FIG.

In this figure, light incident on a television camera device is split into three color lights of red (R) light, green (G) light, and blue (B) light by a color separation prism, and each is separated by an image sensor. The video signals are converted into video signals.
2 and amplified. The video signal amplified by each amplifier is input to a gamma correction circuit 13, a gamma correction circuit 14, and a gamma correction circuit 15, and is subjected to a predetermined gamma correction process.

Further, video signals output from the respective gamma correction circuits, that is, video signals R1, G1, B1 are input to a high luminance compression processing circuit. This high luminance compression processing circuit
An Rch high luminance compression circuit 1 ', a Gch high luminance compression circuit 2', a Bch high luminance compression circuit 3 ', a matrix circuit 5', and addition circuits 16, 17, 18, 19, 20, 21 are input video signals. Is processed so that the signal level becomes equal to or lower than a predetermined level, in particular, the level of the high luminance signal portion is further compressed, and the compressed video signal is output.

In the high luminance compression processing circuit, the video signal R1 is supplied to the Rch high luminance compression circuit 1 'and the addition circuit 16
The video signal G1 is input to the Gch
The video signal B1 is input to the high luminance compression circuit 2 ', the addition circuit 17, and the addition circuit 20, and the video signal B1 is input to the Bch high luminance compression circuit 3', the addition circuit 18, and the addition circuit 21. Each channel high-luminance compression circuit performs signal level compression processing according to the signal level of the input video signal so that the signal level becomes a predetermined level or less, and outputs the video signals as video signals R20, G20, and B20, respectively. . The video signals R20, G20, and B20 are respectively added to an adder 1
6, 17, 18 where the original video signal R
1, G1, and B1 are calculated, and output as difference video signals R30, G30, and B30. The difference video signals R30, G30, and B30 are input to a matrix circuit 5 ', where a matrix operation of the brightness signals is performed, and a difference brightness signal y based on the difference video signals is obtained.
Is output. The difference luminance signal y is added to adders 19 and 20.
And 21 and the video signals R
By subtracting the difference luminance signal y from 1, G1, and B1, high-luminance compression-processed video signals R40, G40, and B40 are generated and output to a subsequent stage (not shown).

[0007]

The above-mentioned prior art improves the change in hue after high luminance compression processing.
The degree of color saturation is set to increase as the luminance increases.

Therefore, an object of the present invention is to realize a high-luminance compression processing circuit in which the degree of color saturation can be reduced as the luminance approaches saturation and the hue does not change.

[0009]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a high-luminance compression circuit for compressing a three-primary-color video signal to a predetermined signal level or less, and a high-luminance compression circuit compressed by the high-luminance compression circuit. Means for multiplying each of the three primary color video signals by a ratio value obtained by dividing a first luminance signal obtained by performing a matrix operation on the video signal by a second luminance signal obtained by performing a matrix operation on the three primary color video signals; It has.

[0010]

FIG. 1 shows an example of an embodiment of the present invention. The light incident on the color television camera device shown in FIG.
Light, green (G) light, and blue (B) light.
Each image signal is converted into a video signal by the image sensor, and each video signal is input to and amplified by the amplifier 10, the amplifier 11, and the amplifier 12, respectively. The video signal amplified by each amplifier is input to a gamma correction circuit 13, a gamma correction circuit 14, and a gamma correction circuit 15, and is subjected to a predetermined gamma correction process.

Further, the video signals output from the respective gamma correction circuits, ie, the video signals R1, G1, B1 are input to the high luminance compression processing circuit. This high luminance compression processing circuit
Rch high luminance compression circuit 1, Gch high luminance compression circuit 2, B
A high-luminance compression circuit 3, a matrix circuit 4, a matrix circuit 5, a division circuit 6, and multiplication circuits 7, 8, and 9 are provided. Particularly, high luminance is set so that the signal level of the input video signal is equal to or lower than a predetermined level. The signal processing is performed so as to further compress the level of the signal portion, and the compressed video signal is output.

In this high luminance compression processing circuit, video signals R1, G1, B1 are input to a matrix circuit 5,
Here, the matrix operation of the luminance signal is performed, and the luminance signal Y1 is output. Further, the video signal R1 is input to the Rch high luminance compression circuit 1 and the multiplication circuit 7, and the video signal G1
1 is input to the Gch high luminance compression circuit 2 and the multiplication circuit 8, and the video signal B1 is input to the Bch high luminance compression circuit 3 and the multiplication circuit 9. In each channel high-luminance compression circuit, a signal level compression process is performed according to the signal level of the input video signal so that the signal level becomes equal to or lower than a predetermined level, and the compressed video signals R2 and G2 are respectively processed. ,
B2 is output. The video signals R2, G2, and B2 are input to the matrix circuit 4, where the matrix operation of the luminance signal is performed, and the luminance signal Y2 is output.

The luminance signal Y1 output from the matrix circuit 5 and the luminance signal Y output from the matrix circuit 4
2 are both input to the division circuit 6, where the luminance signal Y1
And a proportional value Y2 / Y1 of Y2 is calculated, and the value is output from the dividing circuit 6 as a proportional signal.

The ratio signal output from the division circuit 6 is input to multiplication circuits 7, 8, and 9. The multiplication circuits 7, 8, and 9 respectively multiply the video signals R1, G1, and B1 by the proportional values based on the proportional signals from the division circuit 6, thereby compressing the signal levels of the input video signals, and compressing them. The video signals R3, G3, and B3 thus obtained are respectively provided at a subsequent stage (not shown).
Output to

By doing so, the hue of the three primary color video signals (hereinafter referred to as R, G, B video signals) becomes θ = tan−
¹ (((RY) /1.14) / ((BY) /2.0
3)), the hue does not change unless the ratio of the R, G, B video signals changes. Therefore, each of the R, G, and B video signals is multiplied by the ratio Y2 / Y1 of the luminance signal Y1 before compression and the luminance signal Y2 after compression to maintain the ratio of the R, G, and B video signals. Try to compress. The luminance after compression at this time is Y ″ = 0.3R · Y2 / Y1 + 0.596 · Y2 / Y1
+ 0.11B · Y2 / Y1, so that Y ″ = Y2.
The G and B video signals can be respectively compressed at the same ratio, the absolute value of the color difference becomes small, and the saturation does not become too large.

[0016]

As described above, in the high luminance compression circuit of the present invention, the compression can be performed at the same ratio for each of the RGB channel video signals. Hue does not change. Also, since the absolute value of the color difference level does not become too large,
Even at a high luminance, the color is not over arrived.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example of a block configuration of a color television camera device according to the present invention.

FIG. 2 is a diagram showing a block configuration of an example of a conventional color television camera device.

[Explanation of symbols]

1: Rch high luminance compression circuit, 2: Gch high luminance compression circuit, 3: Bch high luminance compression circuit, 4, 5: matrix circuit, 6: division circuit, 7, 8, 9: accumulation circuit,
10, 11, 12: amplifier, 13, 14, 15: gamma correction circuit.

Claims (2)

[Claims] A high luminance compression circuit for compressing the three primary color video signals to a predetermined signal level or less, and a first luminance signal obtained by performing a matrix operation on the video signals compressed by the high luminance compression circuit. Means for multiplying each of the three primary color video signals by a ratio value obtained by dividing the primary color video signal by a second luminance signal obtained by performing a matrix operation, the high luminance compression processing circuit. 2. A color television camera device for obtaining a three-primary-color video signal, a high-luminance compression circuit for compressing the three-primary-color video signal below a predetermined signal level, and a video signal compressed by the high-luminance compression circuit. Means for multiplying the three primary color video signals by a ratio value obtained by dividing a first luminance signal obtained by performing a matrix operation on the three primary color video signals by a second luminance signal obtained by performing a matrix operation on the three primary color video signals. A color television camera device comprising a high luminance compression processing circuit.