Image color adjustment

• US 20050213128A1
• Filed: 03/11/2005
• Published: 09/29/2005
• Est. Priority Date: 03/12/2004
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Fukasawa, Kenji, Imai, Shun
• Granted Patent: US 7,636,473 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: H04N 1/6077 Colour balance, e.g. colour cast correction
• CPC Class Codes: H04N 1/6086 by scene illuminant, i.e. conditions at the time of picture capture, e.g. flash, optical filter used, evening, cloud, daylight, artificial lighting, white point measurement, colour temperature
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

At least one of a plurality of achromatic object color ranges is selected based on the image targeted for processing, and a color adjustment process is executed based on the selected achromatic object color range. Image may be reproduced using a color image data after a color correction of the color image data, the color correction being performed according to illumination light source associated with the color image data. Image data may also be output after the color correction. Image data may also be output associated with data related to the illumination light source, to reproduce the image after the color correction.

Claims

1. An image processing device for adjusting colors in an image targeted for processing, comprising:

an achromatic-object color range selecting module configure to establish a plurality of achromatic-object color ranges each including some colors of an achromatic photographed object in the image targeted for processing, and to select at least one of the plurality of achromatic-object color ranges based on the image targeted for processing; and

a color adjustment processing module configured to perform a color adjusting process on the image targeted for processing based on the selected achromatic-object color range.

2. An image processing device according to claim 1, wherein

the color adjustment processing module includes:

a color balance correction value computing module configured to compute a color balance correction value based on pixel values of achromatic-object-color pixels which have color within the selected achromatic-object color range among pixels of the image targeted for processing; and

a color balancing module configured to perform color balancing on the entire image targeted for processing using the color balance correction value.

3. An image processing device according to claim 2, wherein

the achromatic-object color range selecting module includes

a population index value computing module configured to compute, with respect to each achromatic-object color range, a population index value correlated to the number of pixels having colors within the achromatic-object color range, and

the achromatic-object color range selecting module selects at least that achromatic-object color range which has the greatest population index value among the plurality of achromatic-object color ranges.

4. An image processing device according to claim 3, wherein

the achromatic-object color range selecting module has a two-range selection mode for additionally selecting the achromatic-object color range having the second greatest population index value when a difference of the second greatest population index value and the greatest population index value is less than a difference threshold.

5. An image processing device according to claim 3, wherein

the plurality of achromatic-object color ranges include a predetermined standard achromatic-object color range, and

the achromatic-object color range selecting module has a permissible-range selection mode for selecting one or more achromatic-object color ranges which have a population index value within a permissible value range, the permissible value range including a population index value of the standard achromatic-object color range.

6. An image processing device according to claim 3, wherein

the achromatic-object color range selecting module has a lower-limit selection mode for selecting one or more achromatic-object color ranges having a population index value which is more than a lower limit value.

7. An image processing device according to claim 3, wherein

a pair of the achromatic-object color ranges have an overlapping color range, and the population index value computing module uses pixels values of pixels included in the overlapping color range in the computation of the population index value for both of the achromatic-object color range pair.

8. An image processing device according to claim 3, wherein

a pair of the achromatic-object color ranges have an overlapping color range, and

the population index value computing module use pixels values of pixels included in the overlapping color range in the computation of the population index value for only one of the achromatic-object color range pair.

9. An image processing device according to claim 1, wherein

the color adjustment processing module includes:

a plurality of color conversion profiles associated with the plurality of achromatic-object color ranges, respectively;

a color conversion profile selecting module configured to select a color conversion profile associated with the selected achromatic-object color range from among the plurality of color conversion profiles, and

a color conversion executing module configured to execute a color conversion process on the image targeted for processing according to the selected color conversion profile.

10. An image processing device according to claim 9, wherein

the plurality of achromatic-object color ranges are each associated with a specific light source.

11. An image processing device according to claim 10, wherein

each particular profile of the color conversion profiles is made so that a first color difference between a first processed color value for a predetermined color sample and a colorimetric value of the color sample is smaller than a second color difference between a second processed color value for the color sample and the calorimetric value, the first processed color value being obtained by executing the color conversion process using the particular color conversion profile on a sample image of the color sample photographed under a light source associated with the achromatic-object color range, the second processed color value being obtained by executing the color conversion process on the sample image using another color conversion profile.

12. An image processing device according to claim 11, wherein

the color sample includes color patches in a standard color chart, and

the color conversion profiles are made so that a sum of the first color differences for the color patches is less than a sum of the second color differences for the color patches.

13. An image processing device according to claim 9, wherein

one of the achromatic-object color ranges is pre-selected as a standard achromatic-object color range which is associated with a standard color conversion profile, and

at least one particular profile of the plurality of color conversion profiles other than the standard color conversion profile is made so that first saturation of color obtained by the color conversion process using the particular color conversion profile is less than second saturation of color obtained by the color conversion process using the standard color conversion profile.

14. An image processing device according to claim 13, wherein

the achromatic-object color range selecting module further includes:

a population index value computing module configured to compute, with respect to each achromatic-object color range, a population index value correlated to the number of pixels having colors within the achromatic-object color range, and

the achromatic-object color range selecting module has a standard selection mode for selecting the standard achromatic-object color range when a difference between a population index value of the standard achromatic-object color range and the greatest population index value among the population index values of the plurality of achromatic-object color ranges is less than a standard threshold.

15. An image processing device according to claim 14, wherein

a pair of the achromatic-object color ranges have an overlapping color range, and

the population index value computing module uses pixels values of pixels included in the overlapping color range in the computation of the population index value for both of the achromatic-object color range pair.

16. An image processing device according to claim 14, wherein

a pair of the achromatic-object color ranges have an overlapping color range, and

the population index value computing module use pixels values of pixels included in the overlapping color range in the computation of the population index value for only one of the achromatic-object color range pair.

17. An image processing device according to claim 9, wherein

the plurality of achromatic-object color ranges include a predetermined standard achromatic-object color range, and

the achromatic-object color range selecting module further includes:

a population index value computing module configured to compute, with respect to each achromatic-object color range, a population index value correlated to the number of pixels having colors within the achromatic-object color range, and

the achromatic-object color range selecting module has a standard selection mode for selecting the standard achromatic-object color range when a difference between a population index value of the standard achromatic-object color range and the greatest population index value among the population index values of the plurality of achromatic-object color ranges is less than a standard threshold.

18. An image processing device according to claim 9, wherein

the achromatic-object color range selecting module includes

a population index value computing module configured to compute, with respect to each achromatic-object color range, a population index value correlated to the number of pixels having colors within the achromatic-object color range, and

the achromatic-object color range selecting module has a top selection mode for selecting that achromatic-object color range which has the greatest population index value among the plurality of achromatic-object color ranges.

19. An image processing device according to claim 1, wherein

the plurality of achromatic-object color ranges include:

a locus achromatic-object color range including a locus of colors exhibited by an achromatic object in response to changes in color temperature; and

a non-locus achromatic-object color range which do not include the locus and which do include colors outside the locus achromatic-object color range.

20. An image processing method for adjusting colors in an image targeted for processing, comprising the steps of

(A) providing a plurality of achromatic-object color ranges each including some colors of an achromatic photographed object in the image targeted for processing;

(B) selecting at least one of the plurality of achromatic-object color ranges based on the image targeted for processing; and

(C) performing a color adjusting process on the image targeted for processing based on the selected achromatic-object color range.

21. A computer program product stored on a computer readable medium for adjusting colors in an image targeted for processing, comprising:

(A) a program for causing a computer to select at least one of a plurality of predetermined achromatic-object color ranges based on the image targeted for processing, each of the ranges including some colors of an achromatic photographed object in the image targeted for processing; and

(B) a program for causing the computer to perform a color adjusting process on the image targeted for processing based on the selected achromatic-object color range.

22. An image reproducing method of reproducing an image using color image data, comprising the steps of

(1) generating the color image data by focusing a photographic image on detector elements to detect light intensity over a plurality of wavelength ranges;

(2) acquiring illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

(3) performing a color correction process of the color image data according to illumination light source associated with the color image data; and

(4) reproducing an image using the color image data after the color correction, wherein

the step (3) includes the steps of

providing a plurality of correction parameters representing color correction associated with plural types of illumination light sources, respectively; and

performing the color correction using a correction parameter selected based on the illumination light source data.

23. An image reproducing method according to claim 22, wherein

the step (3) includes the steps of:

providing, as the correction parameters, a plurality of conversion matrices for a linear conversion of the color image data; and

performing the linear conversion of the color image data using a conversion matrix selected based on the illumination light source data.

24. An image reproducing method according to claim 22, wherein

the step (3) includes the steps of:

providing, as the correction parameters, a plurality of conversion tables each representing the color correction suitable to the type of illumination light source usable in shooting a photographic image; and

performing the color correction of the color image data by referencing a conversion table selected based on of the illumination light source data.

25. An image reproducing method of reproducing a photographic image upon receipt of color image data produced by focusing the photographic image on detector elements, comprising the steps of:

(A) receiving illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

(B) performing a color correction process according to the illumination light source upon receipt of the color image data; and

(C) reproducing an image using the color image data after the color correction, wherein

the step (B) includes the steps of,

providing a plurality of correction parameters representing color correction associated with plural types of illumination light sources, respectively; and

performing the color correction of the color image data using a correction parameter selected based on the illumination light source data.

26. An image data output device of outputting color image data generated by focusing a photographic image on detector elements to detect light intensity over a plurality of wavelength ranges, comprising:

a light source data acquisition module configured to acquire illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

a color correction module configured to perform a color correction process of the color image data according to the illumination light source data;

an image data output module configured to output the color image data after the color correction, wherein

the color correction module stores a plurality of correction parameters representing color correction associated with plural types of illumination light sources, respectively, and performs the color correction of the color image data using a correction parameter selected based on the illumination light source data.

27. An image data output device according to claim 26, wherein

the color correction module stores, as the correction parameters, a plurality of conversion matrices for a linear conversion of the color image data, and performs the linear conversion of the color image data using a conversion matrix selected based on the illumination light source data.

28. An image data output device according to claim 27, wherein

the plurality of conversion matrices include a predetermined standard conversion matrix, and

the color correction module performs the linear conversion of the color image data using the standard conversion matrix when no conversion matrix associated with the illumination light source data is available.

29. An image data output device according to claim 26, wherein

the color correction module stores, as correction parameters, a plurality of conversion tables matching the generated color image data with image data that has undergone color correction according to the type of illumination light sources, and performs the color correction of the color image data by referencing a conversion table that has been selected on the basis of the illumination light source data.

30. An image data output device according to claim 29, wherein

the plurality of conversion tables include a predetermined standard conversion table, and

the color correction module performs the color correction of the color image data by referencing the standard conversion table when no conversion table associated with the illumination light source data is available.

31. An image data output device of outputting color image data generated by focusing a photographic image on detector elements to detect light intensity over a plurality of wavelength ranges, comprising:

a light source data acquisition module configured to acquire illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

a correction parameter storage configured to store a plurality of correction parameters for a color correction of the generated color image data, the plurality of correction parameters being associated with plural illumination light sources;

an image data output module configured to select a correction parameter among the plurality of correction parameters based on the illumination light source data, and to output the generated color image data and the selected correction parameter, the generated color image data and the selected correction parameter being associated with each other.

32. An image data output device according to claim 31, wherein

the correction parameter storage stores, as the correction parameters, a plurality of conversion matrices for a linear conversion of the color image data according to the type of illumination light source, and

the image data output module outputs the color image data and the selected conversion matrix among the plurality of conversion matrices, the color image data and the selected conversion matrix being associated with each other.

33. An image data output device according to claim 32, wherein

the correction parameter storage stores a conversion matrix as a standard conversion matrix, among the plurality of conversion matrices, and

the image data output module outputs the standard conversion matrix when no conversion matrix associated with the illumination light source data is available, the standard conversion matrix and the color image data being associated with each other.

34. An image data output device according to claim 31, wherein

the correction parameter storage stores, as correction parameters, a plurality of conversion tables matching the generated color image data with image data that has undergone color correction according to the type of illumination light source, and

the image data output module outputs the color image data and the selected conversion table among the plurality of conversion tables, the color image data and the selected conversion table being associated with each other.

35. An image data output device according to claim 34, wherein

the correction parameter storage stores a conversion table as a standard conversion table, among the plurality of conversion tables, and

the image data output module outputs the standard conversion table when no conversion table associated with the illumination light source data is available, the standard conversion table and the color image data being associated with each other.

36. An image data output device of outputting color image data generated by focusing a photographic image on detector elements to detect light intensity over a plurality of wavelength ranges, comprising:

a correction parameter storage configured to store a plurality of correction parameters for a color correction of the generated color image data according to an illumination light source of the photographic image; and

an image data output module configured to output the color image data and the plurality of correction parameters, the color image data and the plurality of correction parameters being associated with each other.

37. An image data output device according to claim 36, wherein

the correction parameter storage stores, as the correction parameters, a plurality of conversion matrices for a linear conversion of the color image data according to the type of illumination light source.

38. An image data output device according to claim 36, wherein

the correction parameter storage stores, as correction parameters, a plurality of conversion tables matching the generated color image data with image data that has undergone color correction according to the type of illumination light source.

39. An image reproducing device of reproducing a photographic image upon receipt of color image data produced by focusing the photographic image on detector elements, comprising:

a light source data receiving module configured to receive illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

a color correction module configured to perform a color correction process according to the illumination light source upon receipt of the color image data; and

an image reproducing module configured to reproduce an image using the color image data after the color correction, wherein

the color correction module stores a plurality of correction parameters representing color correction associated with plural types of illumination light sources, respectively, and performs the color correction of the color image data using a correction parameter selected based on the illumination light source data.

40. An image reproducing device according to claim 39, wherein

the color correction module stores, as the correction parameters, a plurality of conversion matrices for a linear conversion of the color image data, and performs the linear conversion of the color image data using a conversion matrix selected based on the illumination light source data.

41. An image reproducing device according to claim 39, wherein

the color correction module stores, as correction parameters, a plurality of conversion tables matching the generated color image data with image data that has undergone color correction according to the type of illumination light sources, and performs the color correction of the color image data by referencing a conversion table that has been selected on the basis of the illumination light source data.

42. An image reproducing device of reproducing a photographic image upon receipt of color image data produced by focusing the photographic image on detector elements, comprising:

a correction parameter receiving module configured to receive a plurality of correction parameters associated with the color image data, the plurality of correction parameters being for a color correction of the produced color image data according to an illumination light source used in shooting the photographic image;

a color correction module configured to perform a color correction process of the color image data according to a correction parameter selected among the received plurality of correction parameters; and

an image reproducing module configured to reproduce an image using the color image data after the color correction.

43. An image data output method of outputting color image data generated by focusing a photographic image on detector elements to detect light intensity over a plurality of wavelength ranges, comprising the steps of:

(A) acquiring illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

(B) performing a color correction process of the color image data according to the illumination light source data; and

(C) outputting the color image data after the color correction, wherein

the step (B) includes the steps of;

providing a plurality of correction parameters representing color correction associated with plural types of illumination light sources, respectively; and

performing the color correction using a correction parameter selected based on the illumination light source data.

44. A computer program product stored on a computer readable medium for processing for reproducing an image using color image data generated by focusing a photographic image on detector elements to detect light intensity over a plurality of wavelength ranges, the computer program product comprising:

(1) a program for causing a computer to acquire illumination light source data, the illumination light source data being indicative of a type of an illumination light source used during shooting of the color image data;

(2) a program for causing the computer to perform a color correction process of the color image data according to illumination light source associated with the color image data; and

(3) a program for causing the computer to reproduce an image using the color image data after the color correction, wherein

the program (2) includes;

a program for causing the computer to perform the color correction using a correction parameter selected based on the illumination light source data among a plurality of predetermined correction parameters, the plurality of correction parameters representing color correction associated with plural types of illumination light sources, respectively.