IMAGE FORMING APPARATUS AND COLOR CONVERTING METHOD THEREOF

• US 20080297817A1
• Filed: 01/11/2008
• Published: 12/04/2008
• Est. Priority Date: 06/01/2007
• Status: Active Grant

• Current Assignee: S-Printing Solution Co., Ltd. (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Park, In-ho, Hong, Jin-kyung, Choi, Woo-ri, Shin, Jae-min
• Granted Patent: US 8,363,267 B2
• Time in Patent Office: Days
• US Class Current: 358/1.9
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut

Abstract

An image forming apparatus including a scanning unit to scan an image and to output corresponding digital color coordinates; a determining unit to determine a local color gamut including the digital color coordinates, based on a reference matrix computed from a standard color gamut, which includes the local color gamut, and the plurality of digital color coordinates; a matrix selecting unit to select a color conversion matrix that corresponds to the determined local color gamut; and a computing unit to compute LAB color coordinates based on the selected color conversion matrix and the digital color coordinates. A method of color conversion using the image forming apparatus is also provided.

Claims

1. An image forming apparatus, comprising:

a scanning unit to scan an image and to output corresponding digital color coordinates;

a determining unit to determine a local color gamut, including the digital color coordinates, from a standard color gamut including a plurality of local color gamuts, based on a reference matrix computed from the standard color gamut and the digital color coordinates;

a matrix selecting unit to select a color conversion matrix that corresponds to the local color gamut, from color conversion matrices corresponding to the plurality of local color gamuts; and

a computing unit to compute LAB color coordinates based on the selected color conversion matrix and the digital color coordinates.

2. The image forming apparatus of claim 1, wherein the determining unit comprises:

a temporary computing unit to compute temporary LAB color coordinates corresponding to each of the digital color coordinates, based on the reference matrix and the digital color coordinates; and

a color gamut determining unit to determine the local color gamut, such that the determined local color gamut comprises the temporary LAB color coordinates.

3. The image forming apparatus of claim 1, further comprising:

a color measuring unit to color-measure the image and to output corresponding color-measured LAB color coordinates; and

a matrix computing unit to compute the reference matrix and the color conversion matrices corresponding to the plurality of local color gamuts, based on the color-measured LAB color coordinates and the digital color coordinates.

4. The image forming apparatus of claim 3, wherein the matrix computing unit comprises:

a reference matrix computing unit to compute the reference matrix, which represents a correlation between the color-measured LAB color coordinates and the digital color coordinates; and

a color conversion matrix computing unit to compute the color conversion matrices according to the color-measured LAB color coordinates corresponding to each of the plurality of local color gamuts and the digital color coordinates.

5. The image forming apparatus of claim 2, further comprising a storage unit to store the reference matrix and the color conversion matrices.

6. The image forming apparatus of claim 1, wherein the plurality of local color gamuts comprise one or more chromatic regions, and one or more achromatic regions, and if the local color gamuts comprise a plurality of the chromatic regions, portions of the chromatic regions are overlapped with each other in the standard color gamut.

7. The image forming apparatus of claim 1, further comprising a converting unit to convert the LAB color coordinates into a display signal and/or print signal.

8. A color converting method, comprising:

scanning an image and outputting corresponding digital color coordinates;

determining a local color gamut of a standard color gamut, based on a reference matrix computed from the standard color gamut and the digital color coordinates,

wherein the standard color gamut comprises a plurality of local color gamuts, and the determined local color gamut comprises the digital coordinates;

selecting a color conversion matrix that corresponds to the determined local color gamut, from color conversion matrices corresponding to the plurality of local color gamuts; and

computing LAB color coordinates based on the selected color conversion matrix and the digital color coordinates.

9. The color converting method of claim 8, wherein:

the determining comprises computing temporary LAB color coordinates that correspond to each of the digital color coordinates, based on the reference matrix and the digital color coordinates; and

the determined local color gamut includes the temporary LAB color coordinates.

10. The color converting method of claim 8, further comprising:

color-measuring the image and outputting corresponding color-measured LAB color coordinates;

computing the reference matrix; and

computing the color conversion matrices with respect to each of the plurality of local color gamuts, based on the color-measured LAB color coordinates and the digital color coordinates.

11. The color converting method of claim 10, wherein:

the reference matrix represents a correlation between the color-measured LAB color coordinates and the digital color coordinates; and

computing the color conversion matrices of the plurality of local color gamuts comprises using the color-measured LAB color coordinates in each of the local color gamuts and the digital color coordinates.

12. The color converting method of claim 8, wherein the local color gamuts comprise one or more chromatic regions, and one or more achromatic regions.

13. The image forming apparatus of claim 9, further comprising a comparison unit to compare the LAB color coordinates and the color-measured LAB color coordinates to compute a color difference value.

14. An image forming apparatus, comprising:

a determining unit to determine a local color gamut, including digital color coordinates of a scanned image, from a standard color gamut including a plurality of local color gamuts, based on a reference matrix computed from the standard color gamut and the digital color coordinates;

a matrix selecting unit to select a color conversion matrix that corresponds to the local color gamut, from color conversion matrices corresponding to the plurality of local color gamuts; and

a computing unit to compute LAB color coordinates based on the selected color conversion matrix and the digital color coordinates.

15. An image forming apparatus, comprising:

a Gaussian mixture model (GMM) unit to apply a GMM more than once, to LAB color coordinates acquired by scanning a training sample image, and to provide color gamut characteristics of the training sample image; and

an output unit to output the color gamut characteristics.

16. The image forming apparatus of claim 15, wherein the output unit comprises at least one of:

a display unit to display the provided color gamut characteristics, as a displayable signal on a screen; and

a printing unit to print the provided color gamut characteristics on a printing medium.

17. The image forming apparatus of claim 15, wherein the GMM unit groups the LAB color coordinates of the training sample image into local color gamuts, which are used when a piecewise regression is applied to the training sample image.

18. An image forming apparatus, comprising:

a scanning unit to scan a training sample image; and

an output unit to output LAB color coordinates grouped into local color gamuts, which are used when a piecewise regression is applied to the training sample image, if a GMM is applied to the LAB coordinates.