JPS60187828A - Hue discrimination circuit - Google Patents

Abstract

PURPOSE:To enable the stable judgement of hue even if brightness of illumination changes, by performing color discrimination in a definite three-primary- colors ratio to a difinite color phase. CONSTITUTION:The image signal from a color TV camera 1 is separated into three primary colors of red, green and blue by a color component separation apparatus 2 and color components are digitalized by A/D converters 3a-3c to be inputted to hue data converter circuits 7a-7c through multiplexers 4a-4c. The signal of the camera 1 is inputted to a synchronous separation circuit 5 where a horizontal/vertical synchronous signal is extracted while the clock signal corresponding to a picture element is generated by a reading timing generation circuit 6. The input data of the hue data converter circuits 7a-7c are converted by the output signal of the circuit 6 and appear in output. Color component data normalized in the circuits 7a-7c are stored in image memories 8a-8c and the judgement of the hue is performed by a computer 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a hue discrimination circuit, and particularly to a circuit capable of stable hue discrimination even when the brightness of illumination light or the like changes.

[Background of the invention]

Conventionally, object color determination has been roughly divided into two types: one that uses spectroscopic analysis, and the other that uses the component ratio of 3) jA colors (red, green, and blue) (three primary color method). The method of examining wavelength characteristics using spectroscopic analysis is said to be the most accurate method for determining hue, but it has problems in terms of large scale and speed of determination, and is naive. When present, it was not possible to measure each separately.

On the other hand, in the three primary color method, the three primary color filters of red, green, and blue are installed on the surface of a phototube or photoconductive element, and the hue is determined by the valley output voltage ratio, but the brightness of the illumination light is When the color changes, the output component ratios of the three primary colors become different, and strictly constant illumination conditions are required for stable hue determination.

[Purpose of the invention]

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-described drawbacks of the prior art and to provide a hue determination circuit that can perform reliable hue determination even when the brightness of illumination or the like changes.

[Summary of the invention]

The hue discrimination circuit according to the present invention includes a color TV camera, a color component separation circuit that separates the video signal into three primary color components of red, green, and blue, and an A/D that digitizes each separated color component. A converter, an image memory for accumulating each color component data decoded based on pre-given conversion data, and creating the above conversion data,
Calculate the component ratio of the three primary colors for each color component data above,
The conversion data for correcting the color sensitivity is obtained from the primary color component values when the white reference plate is imaged with the color TV camera while changing the brightness of the illumination light. Then, the value is stored in the hue data conversion circuit, so that hue discrimination can be performed with a constant ratio of the three primary colors for a constant hue.

[Embodiments of the invention]

Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a block diagram of an embodiment of the hue discrimination circuit according to the present invention, FIG. 2 is a timing diagram of its readout signal, and FIG.
4 is a diagram showing the principle of the same hue data conversion, and FIG. 5 is an explanatory diagram of the process of creating the conversion data.

Here, 1 is a color TV camera, 2 is a color component separation circuit,
3a, 3b, 3C are A/D converters; 4a;

4b, 4C are multiplexers, 5 is a synchronization separation circuit, 6 is a read timing generation circuit, 7a+7b, 7c are hue data conversion circuits, 8a, 8b, 8c are image memories, 9 is a computer related to the processing device, 1° is conversion data ,lla,
llb, il, c are selection signals, 12a, 12b, 12C
1 is a write timing signal, 13 is a white reference plate, 14 is a lighting device, ] 5 is a lighting control device, and 16 is a main hue discrimination circuit.

In FIG. 1, a video signal from a color TV camera J is separated by a color component separation circuit 2 into three primary color components of red, green, and blue. Each color component is digitized into, for example, 8 bits by A/D converters 3a to 3C, and then passed through multiplexers 4a to 4C to hue data conversion circuits 7a to 7.
The hue data conversion circuits 7a to 7C input to C are, for example, 256 x 8 bit RA, M (random access memory), and the outputs of the multiplexers 4a to 4C become the memory addresses of the hue data conversion circuits 7a to 7C. Let's do it like this. On the other hand, from the signal of the color TV camera 1, horizontal and vertical synchronization signals are extracted by a synchronization separation circuit 5, and from these, a clock signal corresponding to a pixel is generated by a read timing generation circuit 6. FIG. 2(a) shows the extracted horizontal synchronizing signal, and FIG. 2(b) shows this, for example.

The clock signal is divided into 256 equal parts.

Now, in FIG. 1, the input data of the hue data conversion circuits 7a to 7C is converted by the output signal of the read timing generation circuit 6 and appears at the output.

The hue data conversion circuits 7a to 7C include, as described later,
Conversion data is stored so that the color component data has a constant ratio to white regardless of the brightness. The color component data normalized by the hue data conversion circuits 7a to 7C are stored in image memories 1) 8a to 8C, and the computer 9 calculates the component ratios of the three colors to determine the hue.

Next, writing of conversion data will be explained.

As mentioned above, the conversion data is for correcting changes in color sensitivity due to changes in brightness, and is created by the method described above, but the computer 9 outputs conversion data 10 (8 bits in this example). do.

The selection signals 113 to 11C are selection signals for causing the multiplexer 4 to select the converted data 10, and the write timing signals 12a to 12C are for the write timing.

FIG. 3 shows the arrangement of the apparatus when presenting converted data. A white reference plate 13 is imaged with a color TV camera 1. At this time, the white reference plate 13 is illuminated by the illumination device 14, and the intensity of the illumination light can be varied by the illumination control device 15. The color component value data obtained when the intensity of the illumination light is varied in this way is input to the aforementioned hue discrimination circuit 16 to create conversion data.

FIG. 4 shows the principle of hue data conversion.

The white reference plate 13 is imaged by the color TV camera 1 to obtain digitized color component values (r+g+1). These color component values change as shown in FIGS. 4(a) to 4(c), for example, when the brightness of the white reference plate 13 is changed by changing the intensity of illumination. This is because the gamma correction of the color TV camera 1 varies for each color. Therefore, under a certain brightness tn, the white reference plate 13 is set to the color TV camera 1.
Then, the ratio of green and blue is r, /(rn0gn+b
, ).

g,, / (r, +gn+b,) + bn/ (rn
+g+i+bn), change the brightness in advance as shown in Figure 3, check the changes in each color component value with respect to brightness, calculate the data conversion coefficient for brightness based on that, and convert it to hue data. Conversion circuits 7a-7
If stored in C, the output voltages re, ge will be linear with respect to changes in brightness, as shown in FIGS. 4(d) to (f).
+ Can attend be. This means that regardless of the brightness, when the white reference plate 13 is viewed with the color TV camera 1, a constant component ratio can be obtained, and the sensitivity has also been corrected for various ordinary colors. Therefore, stable hue determination can be performed even when the brightness changes.

Next, the actual method of converting data will be shown. -For example,
A method of dividing the brightness into 10 equal parts and performing linear interpolation between them will be described. In Fig. 3, the brightness of the white reference plate 13 is measured with a luminance meter (not shown), the maximum brightness t is set, and the illuminance is gradually reduced, and each of the 10 brightness levels is adjusted as shown in Fig. 5. Obtain each color component value r+g,b at the time.

If the maximum value when digitizing color component values is ■,
In the case of 8 bits, V=255. At this time, for example, for the red component, when rn<r<rn+1, the component value r8 after conversion is r. -1 (n + -) ・・・・・・・・・(1)1
0rn+lrll. However, n-0 to n-9. In this way,
r for r from 0 to 255. By calculating and storing it in the hue data conversion circuits 78 to 70 in FIG. 1, the relationship between brightness and each color component value can be determined as shown in FIGS. 4(d), (e) and J(f). can get. In this example, the brightness is divided into 10 equal parts, but by dividing the brightness into 10 parts, conversion data with a better linear relationship can be created.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the hue discrimination circuit according to the present invention, FIG. 2 is a timing diagram of its readout signal, and FIG.
4 is a diagram showing the principle of the same hue data conversion, and FIG. 5 is an explanatory diagram of the process of creating the same conversion data. 1... Color TV camera, 2... Color component separation circuit,
3 a, 3 b, 3 C... A/D converter, 4 a,
4b. 4C...Multiplexer, 5...Synchronization separation circuit, 6
...Read timing generation circuit, 7a, 7'b, 7C.
... Hue data conversion circuit, 8a, 8b, 8c... Image memory, 9... Computer, 1o... Conversion data, lla. 11b, IIG--selection signal, 12a, 12b. 12C...Writing timing signal, 13...White reference plate, 1st hard/θ 2nd opening (long Cb) --' ------ 3 hard/'' 5 eyes

Claims (1)

[Claims] 1. A color TV camera, a color component separation circuit that separates the video signal into three primary color components of red, green, and blue, and an A/D conversion circuit that digitizes each separated color component.
a hue data conversion circuit that normalizes each of the separated color components digitized based on conversion data given in advance; and an image memory that stores the normalized data of each color component outputted from the hue data conversion circuit; In addition to creating the above conversion data, 3.
It consists of a processing device that calculates the component ratio of the primary colors and determines the hue thereof, and changes the brightness of the illumination light to produce the color T.
The above conversion data for correcting color sensitivity is obtained from the primary color component values when the white reference plate is imaged with a V camera, and the values are stored in the above hue data conversion circuit and converted to a constant hue. A hue discrimination circuit that can discriminate hues based on a fixed ratio of three primary colors.