Claims
- 1. A color image processing apparatus in which first color-separated image signals, which represent a color, are converted to second color-separated image signals and a black signal, which together represent the same color, said color image processing apparatus comprising:
- input means for inputting first color-separated image signals and a minimum-value signal extracted from the first color-separated image signals;
- calculating means for (i) performing a matrix calculation on both the first color-separated image signals and the minimum-value signal, the matrix calculation using prescribed correction coefficients, and (ii) obtaining second color-separated image signals and a black signal; and
- output means for outputting the second color-separated image signals and the black signal obtained by said calculating means,
- wherein the prescribed correction coefficients are set so that the second color-separated image signals obtained by said calculating means are substantially 0 when the color represented by the first color-separated image signals is an achromatic color.
- 2. The apparatus according to claim 1, wherein said calculating means is implemented by a single matrix calculation.
- 3. A color image processing apparatus according to claim 1, wherein the matrix calculation is performed on all of the first color-separated image signals and the minimum value signal to perform both masking processing and undercolor removal processing on the first color-separated image signals and the minimum value signal in order to obtain the second color-separated image signals and the black signal.
- 4. A color image processing method in which first color-separated image signals, which represent a color, are converted to second color-separated image signals and a black signal, which together represent the same color, said color image processing method comprising the steps of:
- inputting first color-separated image signals and a minimum-value signal extracted from the first color-separated image signals;
- performing a matrix calculation on both the first color-separated image signals and the minimum-value signal, the matrix calculation using prescribed correction coefficients, and obtaining second color-separated image signals and a black signal; and
- outputting the second color-separated image signals and the black signal obtained by the matrix calculation,
- wherein the prescribed correction coefficients are set so that the second color-separated image signals obtained by the matrix calculation are substantially 0 when the color represented by the first color-separated image signals is an achromatic color.
- 5. The method according to claim 4, wherein the matrix calculation is implemented by a single matrix calculation.
- 6. A color image processing method according to claim 4, wherein the matrix calculation is performed on all of the first color-separated image signals and the minimum value signal to perform both masking processing and undercolor removal processing on the first color-separated image signals and the minimum value signal in order to obtain the second color-separated image signals and the black signal.
- 7. A color image processing apparatus in which first color-separated image signals, which represent a color, are converted to second color-separated image signals and a black signal, which together represent the same color, said color image processing apparatus comprising:
- logarithmic converting means for logarithmically converting input color signals into first color-separated image signals;
- minimum-value extracting means for extracting a minimum-value signal pixel by pixel based upon the first color-separated image signals converted by said logarithmic converting means;
- transformation means for subjecting both the first color-separated image signals and the minimum-value signal extracted by the minimum-value extracting means to a matrix transformation in accordance with prescribed transformation coefficients so as to produce second color-separated image signals and a black signal; and
- output means for outputting the second color-separated image signals and the black signal which are obtained by said transformation means,
- wherein the prescribed transformation coefficients are set so that a sum of prescribed terms related to the first color-separated image signals is one of 0 and a value approximating 0.
- 8. A color image processing apparatus according to claim 7, wherein all of the first color-separated image signals and the minimum value signal are subjected to the matrix transformation to perform both masking processing and undercolor removal processing on the first color-separated image signals and the minimum value signal in order to produce the second color-separated image signals and the black signal.
- 9. A color image processing method in which first color-separated image signals, which represent a color, are converted to second color-separated image signals and a black signal, which together represent the same color, said color image processing method comprising the steps of:
- logarithmically converting input color signals into first color-separated image signals;
- extracting a minimum-value signal pixel by pixel based upon the first color-separated image signals converted in said step of logarithmically converting;
- subjecting both the first color-separated image signals and the minimum-value signal extracted in said step of extracting to a matrix transformation in accordance with prescribed transformation coefficients so as to produce second color-separated image signals and a black signal; and
- outputting the second color-separated image signals and the black signal which are obtained by the matrix transformation,
- wherein the prescribed transformation coefficients are set so that a sum of prescribed terms related to the first color-separated image signals is one of 0 and a value approximating 0.
- 10. A color image processing method according to claim 9, wherein all of the first color-separated image signals and the minimum value signal are subjected to the matrix transformation to perform both masking processing and undercolor removal processing on the first color-separated image signals and the minimum value signal in order to produce the second color-separated image signals and the black signal.
- 11. A color image processing method comprising the steps of:
- inputting first color-separated image signals and a minimum-value signal representing a minimum signal among the first color-separated image signals;
- performing a matrix calculation on both the first color-separated image signals and the minimum-value signal, the matrix calculation using correction coefficients, and obtaining second color-separated image signals and a black signal, the correction coefficients being set so that the second color separated image signals are substantially zero when the color represented by the first color-separated image signals is an achromatic color; and
- outputting the second color separated image signals and the black signal obtained by the matrix calculation.
Priority Claims (2)
Number |
Date |
Country |
Kind |
4-226856 |
Aug 1992 |
JPX |
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5-001688 |
Jan 1993 |
JPX |
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Parent Case Info
This application is a continuation of application Ser. No. 08/111,403 filed Aug. 25, 1993, now abandoned.
US Referenced Citations (6)
Foreign Referenced Citations (3)
Number |
Date |
Country |
56-135842 |
Oct 1981 |
JPX |
56-140350 |
Nov 1981 |
JPX |
63-183459 |
Jul 1988 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
111403 |
Aug 1993 |
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