JPS62281067A - Color image processor - Google Patents

Abstract

PURPOSE:To improve the reproducibility of a sensually preferable color, especially, a skin color for a human being by making the hue in a prescribed scope in an image signal close to the hue of a desired memory color. CONSTITUTION:By using a masking circuit 14, the reproduction, of a skin color most noticed by a human being is achieved. The masking circuit 14 is constituted of an HC decoding 20 to convert H and C signals to H' and C' after correction, a converting circuit 21 to reversely convert from Y, H' and C' to Y', R-Y' and B-Y', further, a converting circuit 22 to convert to RGB, further, a converting circuit 23 to convert to Cy, M and Ye, a masking matrix circuit 24 to execute the masking matrix circuit 24 of passage and so forth. Thus, by making the hue of an image signal to be considered to be a skin color into the value to approach to the hue of a 'preferable skin color', the area of the generally distributing skin color can be collected to the area of the 'more preferable skin color', and the improvement of the reproduction of the skin color can be executed.

Description

Detailed Description of the Invention 3. Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a color image processing device that performs predetermined color correction processing on a color image signal.

[Prior Art] Conventionally, a table stored in a ROM or the like is often used for color correction processing such as masking. Taking masking processing as an example, density values of cy (cyan), 1M (magenta), y, and (yellow) are generally used in the ROM input for this processing. At this time, since 13 tree inputs C,,M,YI are input to the masking ROM, C,,M,Y
If each of , is expressed in 8 bits, there will be 224 ways per 1 bit of output of the ROM, resulting in a huge total capacity. Therefore, C, M, and Y are each quantized to reduce the number of bits and used as the input address of the masking ROM, but this quantization is not considered to be quantization suitable for human vision. There's a problem.

[Problems to be Solved by the Invention] That is, as a result of this quantization, for example, a color such as a skin color may be converted into a slightly different "skin color." The above quantization involves similar problems even if the input to the masking ROM is in the form of luminance 71 color difference (RY, BY).

The present invention has been proposed in order to solve the problems of the prior art described above, and its purpose is to propose a color image processing device that outputs color image signals close to memory colors that humans find desirable.

[Means for Solving the Problems] The configuration of the present invention for achieving the above-mentioned problems includes a color image signal correction means that inputs a color image signal consisting of luminance, one hue, and chroma, performs color correction processing, and outputs the color image signal. has.

[Operation] In the present invention configured as described above, when the hue is close to the hue of the memory color of the predetermined color, the color correction processing adjusts the hue in the color image signal to be closer to the hue of the memory color of the predetermined color. Output it as a value.

[Examples] Examples according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram of a color video printer as an embodiment to which the present invention is applied, and its main components include a masking circuit 14 that inputs color difference signals R-Y and B-Y, and a masking circuit 14 in the preceding stage. It has a conversion ROM13. The overall operation is as follows: Y, RY, BY input signals are A/D converted and stored in image memories (10, 11, 12).

Then, the CPU 15 prints Y, R-Y,
B-Y is taken out from the image memory (10, 11, 12). The extracted R-Y and B-Y are l (C conversion ROM 13
It is converted into hue H1 and saturation C. )(C conversion RO
M13 has a color difference signal as its address input, and stores data for converting the color difference signals RY, BY to hue H1 saturation C. Y, H, C are masking circuits 14
, cy' (cyan), M' (magenta), Y,'
(yellow), further D/A converted, and printed.

The HC conversion ROM 13 converts the signals RY' and BY' into luminance Y and chroma C. When converting into H (hue) and C (chroma) in this case, quantization as shown in FIG. 2 is performed. That is, in quantization, the RY and B-Y planes are divided into regions surrounded by circles and straight lines, and the values within the regions are represented by points ".". At this time, however, if RY=O, then H=O.

C (saturation) = RY + B-Y, and the angle of deviation from the reference axis is hue H2 The radius of the circle is saturation C
becomes. In addition, in Fig. 2, the output H is 4 bits,
The case where C is 3 bits is shown, and the shaded area 100 indicates an area where a color close to skin color is distributed.

Glue in the diagram. is the hue of skin color in memory color, hl.

h2 is the range of hues that are perceived as skin colors in the quantization shown in FIG. Quantization as shown in Figure 2 only takes H at equal angles and C at equal intervals and uses these values as representative values, so with this kind of quantization, human vision is completely invisible. Not considered.

Therefore, a masking circuit 14 having the configuration shown in FIG. 4 is used to achieve reproduction of the skin color that attracts the most attention to humans. The configuration of this masking circuit 14 includes an HC decoder 20 that converts H and C signals into corrected H' and C' as shown in FIG.
A conversion circuit 21 for inverse conversion into R-Y', B-Y'', a conversion circuit 22 for further conversion into RGB, a conversion circuit 23 for further conversion into C, M, Y, and a masking matrix for performing normal masking processing. The circuit 24 and the like.

First, to explain the HC decoding 20, if the HC conversion ROM 13 outputs H in h bits and C in 2 bits, the hue and saturation for areas other than the skin color area 100 are generally 360 degrees x (h /2n).

C□. It is assumed that x C/(2 to -1). here,
Cff1ax is the maximum saturation. 100 such areas
Then, the HC decode 20 does nothing.

On the other hand, the image signal included in the skin color area 100 is converted to HC R
OM13 becomes HC decode 20 (h bit, ni bit)
, the HC decode 20 outputs h as
If it is between and, as shown in Figure 3, it is more. Output as h゛ close to . Furthermore, the skin color area 1
If consideration is also given to the saturation of
The correction may be applied only to the output of the C conversion ROM 13. It is easy to configure the HC decoder 20 as a ROM, which converts an input as shown in FIG. 2 into an output as shown in FIG. 3.

In this way, by setting the hue of the image signal that is considered to be skin color to a value closer to the hue of "preferred skin color", it becomes possible to concentrate the generally distributed skin color region into the "preferred skin color" region, and the skin color It is possible to improve the reproduction of

The Y, H, and C signals thus obtained are input to a conversion circuit 21 which receives these three signals as input, and undergoes the following conversion.

(RY)'=CxCos H (B-Y)'= CxSIn H Furthermore, by the conversion circuit 22, R= (RY)'+Y'G=IO,3(RY)' +0.11( B-Y)”
) +Y゛B= (B-Y)'+Y' is output, and furthermore, by the conversion circuit 23, C, = -1og
The following transformations are performed: R'M=-1ogG'Ye=-1ogB'. Then, in order to correct the ink asymmetric color components, the following is performed by the masking matrix circuit 24. Here, predetermined all to a33 are constants.

Incidentally, the HC conversion ROM 13 and the HC decode 20 can also be configured in one ROM. Further, although the above embodiment has been described with respect to a video printer, when outputting to a CRT device or the like, a more preferable skin color can be reproduced by displaying the output of the RGB conversion circuit 22 on a CRT.

[Effects of the Invention] As explained above, according to the present invention, by bringing the hue of a predetermined range in an image signal closer to the hue of a desired memory color,
It is possible to reproduce colors that are more sensually pleasing to humans. It is particularly effective in reproducing skin colors.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an image processing device according to an embodiment of the present invention, FIG. 2 is a diagram explaining quantization by the HC conversion ROM and skin color distribution, and FIG. 3 is a diagram explaining the hue of an image signal in the skin color region. FIG. 4 is a detailed diagram of the masking circuit of the embodiment. In the figure, lO~12...image memory, 13...HC conversion RO
M114: Masking circuit, 16: Head driver.

Claims (4)

[Claims] (1) It has a color image signal correction means that inputs a color image signal consisting of brightness, hue, and saturation, performs color correction processing, and outputs the color image signal, and the color correction processing is performed by inputting a color image signal consisting of luminance, hue, and saturation, and performing color correction processing on a memory color whose hue is a predetermined color. A color image processing device characterized in that when the hue is close to the hue, the hue in the color image signal is output as a value closer to the hue of the memory color of the predetermined color. (2) The color correction process is performed only when the hue of the input color image signal is close to the hue of a predetermined color and when the saturation is within a predetermined range. The color image processing device according to item 1. (3) The color image processing device according to claim 1, wherein the color correction means is composed of a conversion table. (4) The color image processing device according to claim 1, wherein the predetermined color is a skin color.