Image processing apparatus with improved color correction

• US 5,828,780 A
• Filed: 12/19/1994
• Issued: 10/27/1998
• Est. Priority Date: 12/21/1993
• Status: Expired due to Term

• Current Assignee: Ricoh Company Limited
• Original Assignee: Ricoh Company Limited
• Inventors: Ooneda, Shougo, Suzuki, Hiroaki
• Primary Examiner(s): COUSO, YON JUNG
• Application Number:
  US08/359,145
• Time in Patent Office: 1,408 Days
• Field of Search: 382/162, 382/164, 382/167, 358/518, 358/520, 358/522
• US Class Current: 382/167
• CPC Class Codes: H04N 1/6027 Correction or control of colour gradation or colour contrast H04N1/6058 takes precedence

Abstract

The present invention provides a color image processing apparatus comprises a virtual device for executing processing in a reverse direction to that in the color image output device in which output color image data in the color image output device corresponds to input color image data and input color image data therein corresponds to output color image data, and a discriminating unit for making a determination as to whether input color image data is within a color reproduction range of the color image output device according to output color image data from the virtual device.

Claims

1. An image processing apparatus comprising:

a virtual device for receiving input color image data, for executing processing in a direction reverse to that in a color image output device, and for outputting output color image data based on said input color image data, said output color image data being in the color space of color image data input into said output color device, said color space having a plurality of dimensions;

a discrimination unit for making a determination as to whether said input color image data is within a color reproduction range according to individual comparisons of values of said output color image data from said virtual device in each of said dimensions in the color space and respective ranges in the color space of the color image output device; and

a color corrector for correcting the input color image data to be within the color reproduction range of the color image output device according to said determination that the input color image data is within the color reproduction range of the color image output device.

2. An image processing apparatus comprising:

a virtual device for receiving input color image data, for executing processing in a direction reverse to that in a color image output device, and for outputting output color image data based on said input color image data, said output color image data being in the color space of color image data input into said output color device, said color space having a plurality of dimensions;

a discrimination unit for making a determination as to whether said input color image data is within a color reproduction range according to individual comparisons of values of said output color image data from said virtual device in each of said dimensions in the color space and respective ranges in the color space of the color image output device;

an operating unit for selecting a color in said input color image data;

a parameter computing unit for computing parameters according to a color selected by said operation unit; and

a color corrector for correcting the input color image data using said parameters to be within the color reproduction range of the color image output device according to said determination that the input color image data is within the color reproduction range of the color image output device.

3. An image processing apparatus according to claim 2, wherein said operating unit selects a color at the central portion of an input image comprising input color image data.

4. An image processing apparatus according to claim 2, wherein said operating unit selects a color of a portion having the maximum area in an input image comprising input color image data.

5. An image processing apparatus comprising:

a color corrector for executing color correction for correcting input color image data using parameters so that the input color image data will be within a color reproduction range of a color image output device;

an image data representing unit for dividing a homogeneous color space into a plurality of regions and having said input color image data present in each region represented by one representative data;

a pixel number counting unit for counting a number of pixels in said input color image data present in a region for each said region;

a discriminating unit for making a determination as to whether said representative data is within a color reproduction range of said color image output device;

a ratio computing unit for computing a ratio of the total number of pixels corresponding to representative data discriminated by said discriminating unit as not inside the color reproduction range vs a number of all pixels in said input color image data; and

a linear compression unit for executing linear compression to said input color image data when the ratio obtained by said ratio computing unit exceeds a specified value.

6. An image processing apparatus according to claim 5, wherein said linear compression unit can change a compression ratio for each said region.

7. An image processing apparatus comprising:

a color corrector for executing color correction for correcting input color image data using parameters so that the input color image data will be within a color reproduction range of a color image output device;

an image data representing unit for dividing a homogeneous color space into a plurality of regions and having said input color image data present in each region represented by one representative data;

a pixel number counting unit for counting a number of pixels in said input color image data present in a region for each said region;

a discriminating unit for making a determination as to whether said representative data is within a color reproduction range of said color image output device;

a ratio computing unit for computing a ratio of the total number of pixels corresponding to representative data discriminated by said discriminating unit as not inside the color reproduction range vs a number of all pixels in said input color image data;

a linear compression unit for executing linear compression to said input color image data when the ratio obtained by said ratio computing unit exceeds a specified value;

an operating unit for selecting a color in said input color image data; and

a parameter computing unit for computing parameters according to the color selected by said operating unit.

8. An image processing apparatus according to claim 7, wherein said linear compression unit can change a compression ration for each said region.

9. An image processing apparatus according to claim 7, wherein said operating unit select a color of the central portion of an input image comprising input color image data.

10. An image processing apparatus according to claim 7, wherein said operating unit selects a color of a portion having the maximum area in an input image comprising input color data.

11. An image processing apparatus comprising:

a color corrector for executing color correction for correcting input color image data so that the input color image data will be within a color reproduction range of a color image output device;

an image data representing unit for dividing a homogeneous color space into a plurality of regions and having said input color image data present in each region represented by one representative data;

a pixel number counting unit for counting a number of pixels in said input color image data present in a region for each said region;

a discriminating unit for making a determination as to whether said representative data is within a color reproduction range of said color image output device;

a ratio computing unit for computing a ratio of the total number of pixels corresponding to representative data discriminated by said discriminating unit as not inside the color reproduction range vs a number of all pixels in said input color image data;

a compression ratio deciding unit for deciding through a computing sequence previously set when the ratio obtained by said ratio computing unit exceeds a specified value;

a compression ratio setting unit for a user to set a compression ratio; and

a linear compression unit for executing linear compression, when a compression ratio is set by said compression ratio setting unit, to said input color image data using the compression ratio and also executing linear compression to said input color image data in other cases according to a compression ratio decided by said compression ratio deciding unit.

12. An image processing apparatus according to claim 11, wherein said compression ratio deciding unit computes a compression ratio for each said region.

13. An image processing apparatus comprising:

a color corrector for executing color correction for correcting input color image data using parameters so that the input color image data will be within a color reproduction range of a color image output device;

an image data representing unit for dividing a homogeneous color space into a plurality of regions and having said input color image data present in each region represented by one representative data;

a pixel number counting unit for counting a number of pixels in said input color image data present in a region for each region;

a discriminating unit for making a determination as to whether said representative data is within a color reproduction range of said color image output device;

a ratio computing unit for computing a ratio of the total number of pixels corresponding to representative data discriminated by said discriminating unit as not inside the color reproduction range vs a number of all pixels in said input color image data;

a compression ratio deciding unit for deciding through a computing sequence previously set when the ratio obtained by said ratio computing unit exceeds a specified value;

a compression ratio setting unit for a user to set a compression ratio;

a linear compression unit for executing linear compression, when a compression ratio is set by said compression ratio setting unit, to said input color image data using the compression ratio and also executing linear compression to said input color image data in other cases according to a compression ratio decided by said compression ratio deciding unit,

an operating unit for selecting a color in said input color image data; and

a parameter computing unit for computing parameters according to the color selected by said operating unit.

14. An image processing apparatus according to claim 13, wherein said compression ratio deciding unit computes a compression ratio for each said region.

15. An image processing apparatus according to claim 13, wherein said operating unit selects a color of the central portion of an input image comprising input color image data.

16. An image processing apparatus according to claim 13, wherein said operating unit selects a color of a portion having the maximum area in an input image comprising input color image data.

17. An image processing apparatus comprising:

a virtual device for receiving input color image data, for executing processing in a direction reverse to that in a color image output device, and for outputting output color image data based on said input color image data, said output color image data being in the color space of color image data input into said output color device, said color space having a plurality of dimensions;

a discrimination unit for making a determination as to whether said input color image data is within a color reproduction range according to individual comparisons of values of said output color image data from said virtual device in each of said dimensions in the color space and respective ranges in the color space of the color image output device;

a color corrector for correcting the input color image data to be within the color reproduction range of the color image output device according to said determination that the input color image data is within the color reproduction range of the color image output device; and

a measuring unit for measuring historical changes of or environmental change for said color image output device.

18. An image processing apparatus according to claim 17, wherein said virtual device selects optimal parameters from a plurality of parameters previously set taking into considerations historical changes of or environmental changes for said color image output device according a result of measurement by said measuring unit, and executes said processing in the reverse direction.

19. An image processing apparatus comprising:

a virtual device for receiving input color image data, for executing processing in a direction reverse to that in a color image output device, and for outputting output color image data based on said input color image data, said output color image data being in the color space of color image data input into said output color device, said color space having a plurality of dimensions;

a discrimination unit for making a determination as to whether said input color image data is within a color reproduction range according to individual comparisons of values of said output color image data from said virtual device in each of said dimensions in the color space and respective ranges in the color space of the color image output device;

a measuring unit for measuring historical changes of or environmental change for said color image output device;

an operating unit for selecting a color in said input color image data;

a parameter computing unit for computing parameters according to a color selected by said operation unit; and

a color corrector for correcting the input color image data using said parameters to be within the color reproduction range of the color image output device according to said determination that the input color image data is within the color reproduction range of the color image output device.

20. Am image processing apparatus according to claim 19, wherein said virtual device selects optimal parameters from a plurality of parameters previously set taking into considerations historical changes of or environmental changes for said color image output device according a result of measurement by said measuring unit, and executes said processing in the reverse direction.

21. An image processing apparatus according to claim 19, wherein said operating unit selects a color of the central portion of an input image comprising input color image data.

22. An image processing apparatus according to claim 19, wherein said operating unit selects a color of a portion having the maximum area in an input image comprising input color image data.

23. An image processing apparatus comprising:

a virtual device for receiving input color image data, for executing processing in a direction reverse to that in a color image output device, and for outputting output color image data based on said input color image data, said output color image data being in the color space of color image data input into said output color device, said color space having a plurality of dimensions;

a discrimination unit for making a determination as to whether said input color image data is within a color reproduction range according to individual comparisons of values of corrected output color image data from said virtual device in each of said dimensions in the color space and respective ranges in the color space of the color image output device;

a color corrector for correcting the input color image data to be within the color reproduction range of the color image output device according to said determination that the input color image data is within the color reproduction range of the color image output device;

a measuring unit for measuring historical changes of or environmental change for said color image output device; and

a correcting unit for correcting said output color image data obtained through said processing in the reverse direction as said corrected output color image data according to a result of measurement by said measuring unit.

24. An image processing apparatus comprising:

a virtual device for receiving input color image data, for executing processing in a direction reverse to that in a color image output device, and for outputting output color image data based on said input color image data, said output color image data being in the color space of color image data input into said output color device, said color space having a plurality of dimensions;

a discrimination unit for making a determination as to whether said input color image data is within a color reproduction range according to individual comparisons of values of said corrected output color image data from said virtual device in each of said dimensions in the color space and respective ranges in the color space of the color image output device;

a measuring unit for measuring historical changes of or environmental change for said color image output device;

a correcting unit for correcting said output color image data obtained through said processing in the reverse direction as said corrected output color image data according to a result of measurement by said measuring unit;

an operating unit for selecting a color in said input color image data;

a parameter computing unit for computing parameters according to a color selected by said operation unit; and

a color corrector for correcting the input color image data using said parameters to be within the color reproduction range of the color image output device according to said determination that the input color image data is within the color reproduction range of the color image output device.

25. An image processing apparatus according to claim 24, wherein said operating unit selects a color of the central portion in an input image comprising input color image data.

26. An image processing apparatus according to claim 24, wherein said operating unit selects a color of a portion having the maximum area in an input image comprising input color image data.