JPH04267693A - Color detecting circuit - Google Patents

Abstract

PURPOSE:To realize the color detecting circuit suitable for a video signal processing circuit for High Vision (HDTV). CONSTITUTION:Since a chromaticity point of three primary colors in the High Vision system is set to a spot of a picture tube, threshold voltages ER, EG, EB are directly obtained by a matrix computing element 1 based on a chromaticity coordinate (x,y) of a color desired to be detected and a reflectance Y and an output is obtained from comparators 2a, 2b, 2c when coincident and a coincidence output 6 is featured to be outputted as a color desired to be detected when the R, G, B are all coincident.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] The present invention relates to color detection in high-definition image processing circuits of video-related equipment such as high-definition receivers and high-definition monitors.

0002

2. Description of the Related Art FIG. 2 shows a block diagram of a conventional color detection circuit, and FIG. 3 shows a vector diagram of a carrier color signal. 10 is a band amplifier that extracts a color signal from an input NTSC signal; 11a;
, 11b are synchronous detectors with detection axes R1 and R2, 1
2a and 12b are the detection axes R1 and 12b of the color subcarrier SC,
R2 phase shift circuit, 13 an amplifier, 14 an inverting amplifier,
15 is a synthesizer. In the NTSC system, a color subcarrier (color burst) is added to the video signal, so the carrier color signals θ1 and θ2 of the area to be detected are set based on the phase of the color burst as shown in FIG. The color identification signal 16 in a predetermined region θ is detected by output obtained by synchronously detecting the chromaticity signal with the color subcarriers of the detection axes R1 and R2, respectively. Therefore, it is impossible to detect colors without a color burst, and detection is only possible in a certain range of colors.

0003

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional example, and it is an object of the present invention to provide a color detection circuit adapted to high-definition television (HDTV) that is not related to color burst.

0004

[Means to solve the problem] High-definition (HDTV)
), the chromaticity points of the three primary colors are set close to the light emitting point of the picture tube CRT, so the present invention performs matrix calculation from the chromaticity coordinates (x, y) of the color to be detected and the reflectance Y. It is characterized by directly determining the threshold voltage.

[0005]

[Operation] As shown in FIG.
It consists of a circuit configuration of comparators 2a, 2b, 2c corresponding to G and B, and an AND gate circuit 5, and gives the chromaticity coordinates (x, y) and reflectance Y of the color to be detected, and converts x, y, Y into a matrix. Compare each of the calculated outputs ER, EG, and EB with high-definition (HDTV) input signals R, G, and B, and when all R, G, and B match, the AND gate circuit 5
A matching output 6 is then output as the detected color.

[0006]

[Example] In high-definition TV (HDTV), the chromaticity points of the three primary colors are set close to the light emitting point of the picture tube CRT, so colors can be detected by combining the levels of R, G, and B signals. . 1 in Fig. 1 is an arithmetic unit using a matrix that inputs the chromaticity coordinates (x, y) and reflectance Y of the color to be detected and outputs R, G, and B components ER, EG, and EB; 2a, 2b, 2c is a comparator that compares the ER, EG, and EB outputs of the same arithmetic unit 1 with the high-definition input R, G, and B signals and outputs a match, and 5 is an AND gate circuit for the outputs of comparators 2a, 2b, and 2c. be. Assuming that the chromaticity coordinates (x, y) and reflectance Y of the color to be detected are given, the stimulus values X, Y,
Find Z.

[0007]

The relationship between the X, Y, Z stimulus values and the R, G, B stimulus values can be determined once the three primary colors and the chromaticity point of the reference white are determined. For high definition (HDTV)

00
09]

Since the relationship is 0010,

[0011]

[0012] Here, R, G, B stimulus values are 0
It is a value of ~1, which is converted into a voltage value of 0 to 700 mV.

[
0013

[0014] Therefore, the above ER, EG, E
When a combination of B appears, it is detected as a predetermined color. In FIG. 1, ER, EG, and EB are calculated from the above equation for the given x, y, and Y, and the comparators 2a, 2b,
2c outputs the outputs from the comparators 2a, 2b, and 2c when they match, and when all R, G, and B match, the AND gate circuit 5 outputs a match output 6 as the color to be detected. Also, R,
Not only G and B, but also color difference Y, PB and PR signals.

[0015]

Color detection is possible using the following relationship. still,
The calculation may be performed using a microcomputer or a multiplier or the like. Furthermore, if the threshold voltage has a range, it is possible to detect colors in a certain range centered on the color coordinates (x, y) on the chromaticity diagram.

[0017]

Effects of the Invention As described above, the present invention directly calculates the threshold voltage from the chromaticity coordinates (x, y) of the color to be detected and the reflectance Y by matrix calculation.
A color detection circuit adapted to V) can be constructed.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a color detection circuit in high-definition signal processing.

FIG. 2 is a block diagram of a color detection circuit in a conventional NTSC system.

FIG. 3 is a vector diagram of carrier color signals for explaining FIG. 2;

[Explanation of symbols]

1 Arithmetic units such as matrices 2a Comparator 5 AND gate circuit 10 Bandwidth amplifier 11a Synchronous detector 12a Phase shift circuit 13 Amplifier 14 Inverting amplifier 15 Synthesizer

Claims (1)

[Claims] Claim 1: In a video signal processing circuit for high-definition, etc., the chromaticity coordinates (x, y) of the color to be detected and the reflectance Y
When given, x, y, and Y are calculated and the outputs of a matrix calculator that outputs a threshold value corresponding to a predetermined color signal are respectively compared to a first comparator, a second comparator, and a third comparator. In addition to connecting the high-definition R, G, and B signals to the
A comparator, a second comparator, and a third comparator are connected to each other, and the output of the first comparator, the output of the second comparator, and the output of the third comparator are connected to an AND gate with multiple terminal inputs. A color detection circuit connected to a circuit and characterized by direct detection of R, G, B primary color signals or PB, PR color difference signals at threshold voltages.