KR930009875B1 - Color detecting circuit - Google Patents

Abstract

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Description

Color detection circuit

1 is a schematic diagram showing an embodiment in which the color detection circuit according to the present invention is applied to a television receiver.

2 is a schematic diagram showing an embodiment of a color detection circuit.

3 is a connection diagram showing an embodiment of a minimum value calculating circuit.

4 is an operation explanatory diagram of specific color detection.

5 is a characteristic diagram of a specific color detection output.

6 and 7 are schematic diagrams illustrating the prior art.

* Explanation of symbols for main parts of the drawings

10: color detection circuit 10A, 10B: first and second color detection means

14: subtractor 11R to 11B: counting means

5R to 5B: Adder VR to VB: Volume for adjusting the level

The present invention relates to a color detection circuit that can be applied to a color correction system of an image processing circuit such as a television receiver.

In image processing, color correction is often required.

For example, when converting the picture content of a film into a video signal or converting an aerial photograph into a video signal, after modifying a specific color among them, or after highlighting a specific color, Needs to be converted to a video signal.

In a television receiver or the like, there is a case where a specific color of a television image is to be corrected to a favorite color.

For example, when a television receiver is described, when the red color is to be emphasized more than other colors, it may be configured as shown in FIG. In the drawing, the red to blue primary color signals supplied to the terminals 1R, 1G, and 1B are supplied to the corresponding cathodes 2R to 2B of the water tube CRT 2, and at the same time, the red signal SR The color correction circuit 3R is provided on the transmission path.

The color correction circuit 3R comprises a counter 4 and an adder 5, and the red signal SR rises above the other color signals by appropriately adjusting the coefficient of the counter 4, so that the red component is different on the screen. The output is emphasized rather than the color components.

When not only red color but also other colors are desired to be corrected at the same time, the configuration may be performed as shown in FIG.

In this case, if the color correction circuits 3R to 3B are connected to each of the three channels, and the appropriate color correction circuit is adjusted, the desired color can be corrected.

By the way, in the color correction means shown in Fig. 6, only specific primary colors can be corrected. In addition, while the color correction means of FIG. 7 can correct the color to a color like liking, for example, red or blue color components irrelevant to the color are corrected. have.

The present invention has solved such a problem, and it is possible to correct any particular color, while reducing the amount of correction for a specific color, and for other colors based on the specific color correction. As much as possible to avoid the impact of.

For this reason, in the present invention, as shown in Fig. 1, a color detection circuit 10 capable of detecting a specific color is provided in the color correction system for image processing. 1st color detection means 10A and 2nd color detection means 10B, and the 1st color detection means 10A carries out the 1st color detection output EW centering on a white component. Obtain a second color detection output ES centered on a color component including a specific color to be detected by the second color detection means 10B, and use their subtracted output EO as a specific color detection output. (See FIG. 5).

The specific color detection output EO controls a specific channel.

The specific color detection output (EO) is at the maximum level for a specific color, and the output is such that the level decreases as the color shifts away from the specific color. Therefore, the color is emphasized only when a specific color signal is supplied. When the other color signal is supplied, the amount of correction of the color signal is small. Therefore, the influence on the other color is very small.

In addition, the specific color can also detect intermediate colors such as flesh color.

FIG. 1 shows an embodiment of the color detection circuit 10 according to the present invention, and this example is a case where the present invention is applied to a skin color correction system in a television receiver shown in FIG.

In FIG. 1, the red to blue signals SR to SB (the amplitude levels ER to EB) supplied to the terminals 1R to 1B are supplied to the corresponding cathodes 2R to 2B of the CRT 2, These red to blue signals SR to SB are supplied to the color detection circuit 10, and the specific color detection output EO is supplied to each channel through means for adjusting the correction level, and in this embodiment, the volumes VR to VB. It is supplied to the installed adders 5R to 5B for signal synthesis.

The color detection circuit 10 is composed of first and second color detection means 10A, 10B and a subtractor 14, as shown in FIG. 2, and the first color detection means 10A. In this example, the minimum operation circuit is used. The second color detecting means 10B is composed of counting means 11R to 11B and minimum value calculating circuit 12 provided in each channel.

The minimum calculation circuits 10A and 12 have PNP-type transistors Qr to Qb common to the emitter and collector as shown in FIG. 3, and have red to blue signals SR to SB at their respective bases. Is supplied, and the output terminal OUT is derived from the common emitter.

Since the transistors Qr to Qb turn on only the transistors to which the minimum level of the red to blue signals SR to SB are supplied, the signal of the minimum level of the red to blue signals SR to SB is output at the output terminal OUT. Done.

The coefficients K1 to K3 of the counting means 11R to 11B are regular means determined in accordance with the specific color to be finally detected, and when the specific color to be detected is input, normalized red to blue signals SR 'to SB' Each level (ER 'through EB') is selected to be equal and normalized so that the minimum value is 1 for simplicity. When trying to detect flesh color, if the ratio of each level (ER to EB) at the time of flesh color is KR to KB,

It becomes here

to be. In the case of flesh color,

Because of the accuracy, the coefficients K ₁ to K ₃ of the counting means 11R to 11B are set as follows.

By the way, if the ones shown in Figs. 4A to 4D are input as the levels ER to EB of the red to blue signals SR to SB supplied to the input terminals 1R to 1B, the minimum calculation circuits 10A and 12 are input. ) And the following first and second color detection outputs EW and EW are obtained.

FIG. 4a shows the level relationship (ER: EG: EB = 1: 0.85: 0.7) when flesh is present, and FIG. 4b shows the level relationship (ER: EG: EB = 1: 1: 1) when white. Fig. 4c shows a level relationship (ER = EB > EG) in the case of any other color, while figure 4d shows a level relationship (ER = EG = 0 and EB = 1.0) when only blue is input. It is shown.

In the first color detecting means 10A, since the same counting means 11R to 11B as in the second color detecting means 10B are not provided in each channel, the coefficients of each channel are all one. to be. Therefore, when the signals SR to SB shown in FIGS. 4A to 4D are inputted, as shown by the broken lines in FIGS. 4E to 4H, the minimum among the input signal levels ER to EB itself. A signal having a level is output. In the case of FIG. 4A, the blue signal SB is output, which is used as the first color detection output EW.

In FIG. 4B, since the signal is input at the same level, any one signal (for example, red signal SR) is output. Thus, in the case of FIG. 4C, the green signal SG is output, and in FIG. 4D, the first color detection output EW is zero.

4E to 4H, the output level is lowered when a signal having a color component deviating from the white is input at the maximum level when it is white from the first color detection means 10A. When a single color or a middle color composed of two colors of 100% saturation is input, an output in which the output level is zero is obtained. Therefore, the first color detection output EW becomes a triangular waveform output curve as shown in FIG. 5 curve LW. A point and b point represent the intermediate color which consists of a single color or two colors of 100% of saturation.

On the other hand, since the counting means 11R to 11B are provided in the second color detection means 10B, the signals SR to SB having the level relationship shown in Figs. 4A to 4D are inputted. However, the levels ER 'through EB' of the normalized signals SR 'through SB' obtained at each become as shown in Figs. 4I through 4L. Normally, each level (ER 'through EB') becomes equal when the skin is colored (FIG. 4i), and when the color is white, it becomes the 4j degree. .

Here, the minimum value of the normalized levels (ER 'to EB') in flesh color, and the level (ER ') in white color are equal, and the level is equal to the output level (EW) shown in FIG. 4F. do. In addition, as the input color component is out of the skin color, its output level decreases and becomes zero when it is monochromatic or two-color with 100% saturation. Therefore, the second color detection output ES is equal to the fifth degree curve LS. The output curve of the trapezoidal waveform becomes.

In the subtractor 14, since the first color detection output EW is subtracted from the second color detection output ES, the subtraction output EO is shown by the curve LO of FIG. Likewise, an output curve of a triangular waveform is obtained. That is, it is the maximum when flesh color is obtained, and the level decreases as the color goes from white color to white color, and becomes white to zero, and when the color color is shifted from the flesh color to the non-white direction, it decreases equally and becomes zero at point b.

In this way, since the subtracted output EO is at the maximum level only at the skin color input, the specific color can be detected by the color detection circuit 10, and the subtracted output EO is used as the specific color detection output.

Therefore, when it is desired to correct the skin color slightly red as the flesh color, the specific volume detection output applied to the adders 5G and 5B is adjusted by adjusting the correction volumes VG and VB for the G and B channels to a minimum value. When (EO) is set to zero, and the volume correction volume (VR) is adjusted, and the level-adjusted specific color detection output (EO) is added to the adder 5R, the color is slightly reddish than the color on the image side. Is corrected.

At this time, even when red, green, and blue signals other than the color signal are supplied, the specific color detection output EO shown in FIG. 5B is obtained, and the specific color detection output EO is added to the R channel. At this time, since the EO itself level is small and the level is adjusted again by the volume VR, a color other than flesh color does not become noticeably red even when a specific color detection output EO is added to the R channel. . When EO is white, the correction amount of the R channel is also zero at this time, and the white balance is not destroyed.

When the flesh color is corrected to other favorite flesh color, the level of the volumes VR to VB may be adjusted according to the favorite color, and when counting specific colors other than the flesh color, the counting means 11R to B are used. Just change the coefficient of.

Therefore, even when the present invention is applied to a color correction system for image processing other than a television receiver, for example, a color correction system installed in a conversion system for converting a film image into a video signal, a specific color to be corrected or emphasized should be detected. By setting the coefficients of the counting means 11R to 11B, since the specific color detection output EO such that the color signal representing the specific color to be corrected is attained to the maximum level is obtained, the volumes VR to VB are obtained. ) To adjust or emphasize a particular color.

As described above, according to the present invention, the specific color detection output EO is obtained as the maximum level is obtained when a specific color is obtained and the level is lowered as the level is lowered as a deviation from the specific color. When the color is emphasized only, the color is emphasized and reversed, and when the other color signal is supplied, the correction amount of the color signal is small, so the influence of the other color is very small.

Therefore, only a specific primary color can be corrected as in the prior art. For example, if a color is preferred to a flesh color, the defect can be eliminated from red to blue color components that have nothing to do with flesh color. Have.

Claims (1)

Three video signal lines for supplying respective red, green and blue signals, first color detection means 10A for generating a white component from the means for red, green and blue signals supplied by the three video signal lines, Second color detecting means 10B for generating a color component set from at least two of the red, green, and blue signals supplied by at least two of the three video signal lines, and an output of the first and second color detecting means; And a means (14) for generating a difference signal that is a difference between the signals.

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