JPH03138778A - Color picture emphasizing circuit - Google Patents

Abstract

PURPOSE:To make a color picture clear by adaptively changing the degree of emphasis of color signal components in accordance with the luminance signal component level of a color picture signal. CONSTITUTION:An input luminance signal Y is emphasized by a monochromatic signal emphasizing circuit 1 to obtain an emphasized luminance signal Y', and a first color signal C1 is multiplied by the output (Y'/Y) of a dividing circuit 2 in a first multiplier 3 to obtain a first color signal C1' maintaining the chromaticity. A second color signal C2 is multiplied by the output (Y'/Y) of the dividing circuit 2 in a second multiplier 4 to obtain a second color signal C2' maintaining the chromaticity. The result obtained by multiplying the output C1' (C2') of the multiplier 3 (4) by an output alpha of a weighting value calculating circuit 5 and the result obtained by multiplying the color signal C1 (C2) by an output 1-alpha of a complement calculating circuit 8 are added to obtain an emphasized color signal. Thus, the input color picture is made clear.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a color image enhancement circuit for obtaining clear color image signals through image enhancement processing from signals from robot eyes, surveillance cameras for factory automation, etc. .

(Prior art) Conventionally, as a method for obtaining a clear image from a blurry image, the Proceedings of the
(Proceedings of ICASSP) 1
981, pages 1117 to 1120 is known. In this method, the reason why the image becomes unclear is that the fine fluctuation signals of the image are not sufficiently recorded due to the dynamic range of the projector in extremely weak or strong intensity areas, as shown in Figure 2 (a). As shown in Fig. 2(b), the preferred processing is to increase or decrease extremely weak or strong intensity areas, and to increase or decrease fine fluctuation signals accordingly. That's what I do.

FIG. 3 is a block diagram of a conventional image enhancement circuit that implements the above method. An image signal input from a terminal 31 is input to a low-pass spatial filter 32, and the low-pass spatial filter 32 reduces the average local intensity. A signal is output. on the other hand,
The image signal inputted from the terminal 31 is inputted to the subtracter 33, where the average local intensity signal is removed from the low-pass spatial filter 32, and only the detail signal of the image is obtained. In order to emphasize the detail signals of this image, the average local intensity signal is passed to a multiplier 35 via a first conversion circuit 34 which performs non-linear weighting. That is, the first conversion circuit 34 is configured to output a large value in order to selectively amplify only the detail signal of the image in a portion where the average local intensity signal is extremely weak or strong. Furthermore, if the detailed signals of the image are emphasized in this way and added to the average local intensity signal, the dynamic range of the image may be exceeded.
The second conversion circuit 36 modifies the average local intensity signal, and the adder 37 adds the modified average local intensity and the enhanced image detail signal output from the multiplier 35 to an output terminal. Output from 38. As a result, the appropriate part of the intensity remains the same, and
Portions where the intensity is too strong or too weak can be adjusted and output with emphasis on detailed signals, making it possible to enhance the image.

<Problems to be Solved by the Invention> However, in the conventional method, input image signals are limited to monochrome signals. Also, when dealing with color images, if you perform enhancement while preserving chromaticity, the ratio of each signal after enhancement (luminance signal, first color signal, second color signal) is the ratio between the input color signals. need to be the same. However, the chromaticity in dark shadow areas with a low luminance level includes many errors, so if this chromaticity is maintained and enhanced, the color image quality will deteriorate significantly. On the other hand, if only the luminance signal is emphasized, the hue is preserved, but the color (freshness) deteriorates in areas other than the shape.

An object of the present invention is to provide an image enhancement circuit that can enhance color signals according to a color image.

(Means for Solving the Problems) A color image enhancement circuit of the present invention includes a monochromatic signal enhancement circuit that receives an input luminance signal and emphasizes fine fluctuation components, and an enhanced luminance signal that is the output of the monochromatic signal enhancement circuit. a division circuit that divides by a luminance signal; a first multiplier that multiplies a first input color signal by the output of the division circuit; and a second multiplier that multiplies a second input color signal by the output of the division circuit. and a weighting value calculation circuit which receives an input luminance signal and outputs a value close to O when the value of the input luminance signal is small and outputs a value close to 1 when the value of the input luminance signal is large, and the first multiplier. a third multiplier that multiplies the output by the output of the weighting value calculation circuit; a fourth multiplier that multiplies the output of the second multiplier by the output of the weighting value calculation circuit; a complement calculation circuit for subtracting the output of the value calculation circuit; a fifth multiplier for multiplying the first input color signal by the output of the complement calculation circuit; and a fifth multiplier for multiplying the second input color signal by the output of the complement calculation circuit. a first adder that adds the output of the third multiplier and the output of the fifth multiplier to obtain a first emphasized color signal; and a second adder that adds the output of the multiplier and the output of the sixth multiplier to obtain a second emphasized color signal.

(Operation) The principle of the present invention is to sharpen a color image by adaptively changing the degree of emphasis of a color signal component according to the luminance signal component level of a color image signal. Specifically, when the brightness level is low, the enhancement of color signal components is suppressed to prevent deterioration due to errors contained in the color signal, while when the brightness level is high enough, the emphasis is maintained while maintaining chromaticity, resulting in sharp images. This allows you to obtain a color image.

(Example) Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block circuit diagram showing an embodiment of the present invention, which includes a monochromatic signal emphasis circuit 1, a division circuit 2, a first
multiplier 3, second multiplier 4, weighted direct calculation circuit 5,
Consists of a third multiplier 6, a fourth multiplier 7, a complement calculation circuit 8, a fifth multiplier 9, a sixth multiplier 10, a first adder 11, and a second adder 12. .

The monochromatic signal emphasizing circuit 1 emphasizes the input luminance signal, and the circuit shown in FIG. 3 is used as the monochromatic signal emphasizing circuit 1. The division circuit 2 performs division using the output of the monochromatic signal enhancement circuit 1 as a dividend and the input luminance signal as a divisor.The first multiplier 3 multiplies the first color signal by the output of the division circuit 2. The second multiplier 4 multiplies the second color signal by the output of the division circuit 2. The weighted direct calculation circuit 5 inputs the luminance signal, and when the value of the luminance signal is small, it gives a value close to 0, and when it is large, it gives a value of 1.
Outputs a value close to . The third multiplier 6 is the first multiplier 3
The output of is multiplied by the output of the weighted direct calculation circuit 5. The fourth multiplier 7 multiplies the output of the second multiplier 4 by the output of the weighted direct calculation circuit 5. The complement calculation circuit 8 outputs a value obtained by subtracting the output of the weighted direct calculation circuit 5 from the value 1. The fifth multiplier 9 multiplies the first color signal by the output of the complement calculation circuit 8.

The sixth multiplier 10 multiplies the second color signal by the output of the complement calculation circuit 8. The first adder 11 adds the output of the third multiplier 6 and the output of the fifth multiplier 9, and the second adder 12 adds the output of the fourth multiplier 7 and the sixth multiplier. Addition is performed with the output of the unit 9.

In the color image enhancement circuit of the present invention, an input luminance signal Y is enhanced by a monochromatic signal enhancement circuit 1 to obtain an enhanced luminance signal Y', and a first color signal C1 is processed by a division circuit by a first multiplier 3. The first color signal 01' that preserves chromaticity is obtained by multiplying the output (Y'/Y) of the second color signal C2 by the second multiplier 4 and the division circuit 2.
A second color signal C2' that preserves chromaticity is obtained by multiplying the output (Y'/Y).

Next, the product obtained by multiplying the output C1' of the first multiplier 3 by the output α of the weighted direct calculation circuit 5, and the product obtained by multiplying the first color signal C1 by the output 1-α of the complement calculation circuit 8 are added. By doing so, an enhanced first color signal is obtained. Similarly, the output C2' of the second multiplier 4 is weighted with the output α of the direct calculation circuit 5.
An enhanced second color signal is obtained by adding the product obtained by multiplying the second color signal C2 by the output 1-α of the complement calculation circuit 8.

(Effects of the Invention) As described above, according to the present invention, it is possible to adaptively enhance color signals according to the properties of an input color image, and the input color image can be made clearer.

[Brief explanation of the drawing]

FIG. 1 is a circuit block diagram showing one embodiment of the present invention, and FIG.
The figure shows the principle of a conventional system, and FIG. 3 is a circuit block diagram showing an example of a conventional image enhancement circuit. 1... Monochromatic signal emphasis circuit, 2... Division circuit, 3...
・First multiplier, 4... Second multiplier, 5... Weighted direct calculation circuit, 6... Third multiplier, 7... Fourth
multiplier, 8... complement calculation circuit, 9... fifth multiplier, 10... sixth multiplier, 11... first adder, 12... second addition vessel.

Claims (1)

[Claims] In a color image enhancement circuit that receives a color image signal composed of a luminance signal and first and second color signals as an input signal and emphasizes color signal components, a monochromatic signal that receives an input luminance signal and emphasizes fine fluctuation components. an emphasis circuit, a division circuit that divides the emphasized luminance signal output from the monochromatic signal emphasis circuit by an input luminance signal, a first multiplier that multiplies the first input color signal by the output of the division circuit, and a second multiplier. a second multiplier that multiplies the input color signal by the output of the division circuit; and a second multiplier that receives the input luminance signal and outputs a value close to 0 when the value of the input luminance signal is small, and a value close to 1 when the value of the input luminance signal is large; a third multiplier that multiplies the output of the first multiplier by the output of the weighting value calculation circuit; and a third multiplier that multiplies the output of the second multiplier by the output of the weighting value calculation circuit. a fourth multiplier for multiplying the output; a complement calculation circuit for subtracting the output of the weighting value calculation circuit from 1; a fifth multiplier for multiplying the first input color signal by the output of the complement calculation circuit; a sixth multiplier for multiplying the input color signal by the output of the complement calculation circuit; and a first emphasized color signal by adding the output of the third multiplier and the output of the fifth multiplier. First thing to ask for
and a second adder that adds the output of the fourth multiplier and the output of the sixth multiplier to obtain a second emphasized color signal. Color image enhancement circuit.