Apparatus for reproducing color images

• US 5,546,195 A
• Filed: 08/11/1994
• Issued: 08/13/1996
• Est. Priority Date: 08/11/1994
• Status: Expired due to Fees

• Current Assignee: TOYO Ink Manufacturing Company Limited
• Original Assignee: TOYO Ink Manufacturing Company Limited
• Inventors: Arai, Yoshifumi
• Primary Examiner(s): Rogers, Scott A.
• Application Number:
  US08/289,085
• Time in Patent Office: 733 Days
• Field of Search: 358/518, 358/519, 358/520, 358/523, 382/167, 382/156
• US Class Current: 358/518
• CPC Class Codes: H04N 1/6088 by viewing conditions, i.e. conditions at picture output

Abstract

In a reproduced color correction system, a photometer measures external illuminant light and sends a measured result to a workstation. The workstation determines the type of an illuminant on the basis of the measured result and sends a selection signal and corresponding colorimetric value data to a neural network management unit. The neural network management unit is provided with a plurality of neural networks associated with types of illuminants. The neural network selected according to the selection signal converts the colorimetric value to a color separation value according to a post-learning transformation function. A color printing device outputs a color image on the basis of the generated color separation value. Thus, the neural network associated with the illuminant used for observation reference is selected, and appropriate color transformation is performed. Accordingly, even if the viewing condition is changed, color matching can be performed so that observed reproduced colors are unchanged.

Claims

1. An apparatus for converting X,Y,Z;

L*a*b*;

or L*u*v* colorimetric values of an original color image to R,G,B;

C,M,Y;

or C,M,Y,K, color separation values, the apparatus comprising;

a plurality of converting means for converting the colorimetric values of the original color image which has been obtained under a specific illuminant to the color separation values under a plurality of observation illuminants differing in types;

means for selecting one of said plurality of converting means; and

means for outputting the color image based on the color separation value obtained by said converting means selected by said selecting means, each of said plurality of converting means converting colorimetric values such that observed colors of the color image output by said outputting means under the corresponding illuminant match with colors of the original color image.

2. The apparatus according to claim 1, wherein said selecting means comprises input means operated by an operator.

3. The apparatus according to claim 1, wherein said selecting means comprises photometer means for determining the types of the illuminants and means for selecting one of said plurality of converting means based on a determination result by said photometer means.

4. The apparatus according to claim 1, wherein each of said plurality of converting means comprises a multilayered feed-forward type neural network.

5. The apparatus according to claim 1, wherein each of said plurality of converting means comprises a look-up table.

6. The apparatus according to claim 1, wherein said plurality of converting means comprises means for converting at least one of colorimetric values under a D illuminant with color temperatures of 4000 to 20000[k], fluorescent lamp illuminants of standards F1 to F12, an A illuminant, a B illuminant, and a C illuminant.

7. An apparatus for converting X,Y,Z;

L*a*b*;

or L*u*v* colorimetric values of an original color image to R,G,B;

C,M,Y;

or C,M,Y,K, color separation values, the apparatus comprising;

a plurality of converting means for converting the colorimetric values of the original color image which has been obtained under a plurality of illuminants to the color separation values under a plurality of observation illuminants differing in types;

means for selecting one of said plurality of converting means; and

means for outputting the color image based on the color separation value obtained by said converting means selected by said selecting means, each of said plurality of converting means converting colorimetric values such that observed colors of the color image output by said outputting means under the corresponding illuminant match with colors of the corresponding original color image.

8. The apparatus according to claim 7, wherein said selecting means comprises input means operated by an operator.

9. The apparatus according to claim 7, wherein said selecting means comprises photometer means for determining the types of the illuminants and means for selecting one of said plurality of converting means based on a determination result by said photometer means.

10. The apparatus according to claim 7, wherein each of said plurality of converting means comprises a multilayered feed-forward type neural network.

11. The apparatus according to claim 7, wherein each of said plurality of converting means comprises a look-up table.

12. The apparatus according to claim 7, wherein said plurality of converting means comprises means for converting at least one of colorimetric values under a D illuminant with color temperatures of 4000 to 20000[k], fluorescent lamp illuminants of standards F1 to F12, an A illuminant, a B illuminant, and a C illuminant.

13. An apparatus for converting X,Y,Z;

L*a*b*;

or L*u*v* colorimetric values of an original color image to R,G,B;

C,M,Y;

or C,M,Y,K, color separation values, the apparatus comprising;

a neutral network for converting the colorimetric values to the color separation values, the neural network having neurons connected to each other via given weights;

means for storing plural sets of weights which make said neural network convert the colorimetric values of the original color image which has been obtained under a specific illuminant to plural color separation values under plural observation illuminants differing in types;

means for selectively supplying one of the sets of weights stored in said storing means to said neural network in accordance with an observation illuminant; and

means for outputting the color image based on the color separation value obtained by said neural network supplied with the set of weights selected by said selecting means, each of said plural sets of weights making the neural network convert colorimetric values such that observed colors of the color image output by said outputting means under the corresponding illuminant match with colors of the original color image.

14. An apparatus for converting x,Y,Z;

L*a*b*;

or L*u*v* colorimetric values of an original color image to R,G,B;

C,M,Y;

or C,M,Y,K, color separation values, the apparatus comprising;

a neural network for converting the colorimetric values to the color separation values, the neural network having neurons connected to each other via given weights;

means for storing plural sets of weights which make said neural network convert the colorimetric values of the original color image which has been obtained under plural illuminants to plural color separation values under plural observation illuminants differing in types;

means for selectively supplying one of the sets of weights stored in said storing means to said neural network in accordance with an observation illuminant; and

means for outputting the color image based on the color separation value obtained by said neural network supplied with the set of weights selected by said selecting means, each of said plural sets of weights causing said neural network to convert colorimetric values such that observed colors of the color image output by said outputting means under the corresponding illuminant match with colors of the corresponding original color image.