Color correction system employing reference pictures

• US 5,212,546 A
• Filed: 09/14/1990
• Issued: 05/18/1993
• Est. Priority Date: 07/03/1990
• Status: Expired due to Term

• Current Assignee: Electronics For Imaging Incorporated
• Original Assignee: Electronics For Imaging Incorporated
• Inventors: Bar, Abraham A., Arazi, Efraim, Schreiber, William F.
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US07/582,054
• Time in Patent Office: 977 Days
• Field of Search: 358/75, 358/76, 358/78, 358/80
• US Class Current: 358/518
• CPC Class Codes: H04N 1/6011 with simulation on a subsidiary picture reproducer H04N1/622 takes precedence; matching two or more picture reproducers H04N1/6052

Abstract

The color correction system will enhance an operator'"'"'s ability to edit and correct the appearance of a color image. This system is particularly useful in desk-top publishing applications. A reference image with an overall desired visual impression is displayed on a screen. This reference image is known to print in an acceptable fashion and give a desired visual impression. When the image to be corrected is modified in order to approximate the visual impression of a reference picture, then the picture to be corrected should print acceptably.

Claims

1. A color correction system comprising:

a first image appearance value storage device containing a first set of appearance values which represent a first color image and wherein appearance values are values that represent color and that are RGB values or may be obtained by a reversible transformation of RGB values;

a variable image appearance value adjustment device connected to said first image appearance value storage device;

an image display connected to said variable image appearance value adjustment device;

a second image appearance value storage device containing a second set of appearance values which represent a second color image connected to said display; and

an appearance value to colorant value converter connected to said variable image appearance value adjustment device.

2. A color correction system according to claim 1, wherein said variable image appearance value adjustment device is a user interactive device.

3. A color correction system according to claim 2 further comprising:

a third image appearance value storage device connected between said variable image appearance value adjustment device and said display.

4. A color correction system according to claim 2, wherein said variable image appearance value adjustment device further comprises a multiple variant image appearance generator and a variant selector connected to said generator.

5. A color correction system according to claim 4, wherein said variable image appearance value adjustment device further comprises a selective color correction device.

6. A color correction system according to claim 5, wherein said variable image appearance value adjustment device further comprises a special color correction device.

7. A color correction system according to claim 6 further comprising a white appearance signal generator connected to said display.

8. A color correction system according to claim 7 further comprising:

an address generator connected to said first and second image appearance value storage devices;

a control connected to said display; and

wherein

said display further comprises a switch connected to said variable image appearance value adjustment device, said second image appearance value storage device and said white appearance signal generator, wherein said address generator and said switch are responsive to said control.

9. A color correction system according to claim 2 further comprising:

an address generator connected to said first and second image appearance value storage devices;

a switch connecting said variable image appearance value adjustment device and said second image appearance value storage device to said display, wherein said address generator and said switch are responsive to a control.

10. A color correction system according to claim 2, wherein said variable image appearance value adjustment device comprises at least one nonlinear amplifier of appearance values.

11. A color correction system according to claim 10, wherein said nonlinear amplifier is a lookup table.

12. A color correction system according to claim 10, wherein said variable image appearance valve adjustment device comprises three one-dimensional lookup tables.

13. A color correction system according to claim 12, wherein each of said one dimensional lookup tables is independently variable and corresponds to one signal of a set of appearance signals.

14. A color correction system according to claim 2 further comprising a gamut monitor connected to said variable image appearance value adjustment device.

15. A color correction system according to claim 8, wherein said control comprises means for repositioning images on said display.

16. A color correction device comprising:

a primary image appearance value adjustment unit connected to an image source, wherein appearance values are values that represent color and that are RGB values or values that may be obtained by a reversible transformation of RGB values;

a plurality of variant image appearance value adjustment units connected to said image source;

an adjustment selector connected to said primary image adjustment unit and said variant image adjustment units;

an appearance value to colorant value converter connected to said primary image appearance value adjustment unit.

17. A color correction system according to claim 16, wherein said image source is an image storage device.

18. A color correction system according to claim 16, wherein said image source is a scanner.

19. A color correction system according to claim 16 further comprising means for printing a plurality of images, said means for printing responsive to at least one of said variant image adjustment units.

20. A color correction system according to claim 16, wherein said adjustment selector further comprises an adjustment controller connected to said variant image adjustment units.

21. A color correction system according to claim 20, wherein said adjustment selector unit further comprises a variant selector connected to said adjustment controller.

22. A color correction system according to claim 21, wherein said variant image adjustment units are connected to said primary image adjustment unit.

23. A color correction system according to claim 22, wherein said adjustment selector further comprises an adjustment type selector connected to said adjustment controller.

24. A color correction device according to claim 23, wherein said adjustment selector further comprises an adjustment amount selector connected to said adjustment controller.

25. A color correction device according to claim 24 further comprising a display connected to said image adjustment units.

26. A color correction device according to claim 25 further comprising a reference image source connected to said display and said display is configured to display said variant images and said reference image.

27. A system according to claim 16 further comprising a print engine connected to said appearance value to colorant value converter.

28. A system according to claim 27, wherein said reference image source comprises means, connected to said display, for storing a plurality of reference images;

and

means, connected to said means for storing, for selecting at least one of said reference images.

29. A system according to claim 28, wherein said means for selecting further comprises means for indexing said reference images.

30. A system according to claim 29, wherein said means for indexing comprises means for indexing by characteristics.

31. A method for adjusting color images comprising the steps of:

displaying a first image on a display device, said first image being represented by a first plurality of appearance values, wherein appearance values are values that represent color and that are RGB values or values that may be obtained by a reversible transformation of RGB values;

displaying a second image on a display device, said displaying of said second image being proximate to said first image;

modifying at least a subset of appearance values in said first plurality of appearance values so that a visual impression of said first image is comparable to a visual impression of said second image such that a modified first plurality of appearance values is created;

converting said modified first plurality of appearance values to a plurality of corresponding colorant values.

32. A method according to claim 31 further comprising the step of:

storing a high resolution version of said first image;

said step of displaying said first image comprises the steps of generating a low resolution version of said first image and displaying said low resolution version;

said step of modifying comprises interactively modifying said low resolution version of said first image and when satisfied modifying said high resolution version of said first image; and

said step of converting comprises converting a modified high resolution version of said image appearance values to colorant values.

33. A method according to claim 31, wherein the step of modifying comprises the step of sequentially modifying a series of image characteristics.

34. A method according to claim 32, wherein the step of modifying comprises the steps of:

setting a current modification of said first image;

generating a plurality of variant modifications;

displaying said current modification and said variant modifications;

selecting a modification and replacing the current modification with the selected modification when the selected modification is one of said variant modifications.

35. A method according to claim 34, wherein the step of modifying comprises sequentially modifying a series of characteristics.

36. A method according to claim 34 where the step of modifying is an iterative step where a first iteration of the generating step generates a plurality of coarse variant modifications and in one or more subsequent iterations the generating step generates successively finer variant modifications.

37. A method according to claim 31, further comprising the step of displaying one or more additional images.

38. A method according to claim 31, wherein said step of modifying further comprises the step of selective color correction.

39. A method according to claim 38, wherein said step of modifying further comprises a step of special color correction.

40. A method according to claim 33, wherein said step of modifying further comprises the steps of:

sampling one or more points of said first image;

selecting a set of points proximate to said sampled points;

sampling one or more points of said second image;

modifying said set of points of said first image in accordance with the appearance values of said points sampled from said second image.

41. A method according to claim 40, wherein said step of selecting a set of points proximate to said sampled points comprises selecting a spatially proximate set of points.

42. A method according to claim 41, wherein said step of selecting comprises selecting a set of points having proximate color values.

43. A method according to claim 42, wherein the step of selecting comprises selecting a set of spatially contiguous points having proximate color values.

44. A method according to claim 31, wherein the step of displaying said second image comprises displaying a second image in the same class as said first image and which is known to print acceptably.

45. A method according to claim 32, wherein said step of modifying said high resolution version o said first image effects the same modifications as the step of modifying said low resolution version.

46. A method according to claim 31, wherein said step of modifying further comprises a step of special color correction.

47. A method according to claim 31, wherein the step of displaying said second image comprises the step of displaying an image intended to appear on the same page as said first image.

48. A method according to claim 32, wherein said step of modifying comprises modifying brightness, contrast and color balance of said first image.

51. A method according to claim 31, wherein the step of modifying comprises the steps of:

setting a current modification of said first image;

generating a plurality of variant modifications;

displaying said current modification and said variant modifications; and

selecting a modification and replacing the current modification with the selected modification when the selected modification is one of said variant modifications.

52. A method according to claim 51, wherein the step of modifying comprises sequentially modifying a series of characteristics.

53. A method according to claim 51, wherein the step of modifying is an iterative step where a first iteration of the generating step generates a plurality of coarse variant modifications and in one or more subsequent iterations the generating step generates successively finer variant modifications.

54. A method according to claim 40, wherein said step of selecting comprises selecting a set of points having proximate color values.

55. A method according to claim 31, wherein said step of modifying further comprises the steps of:

sampling one or more points of said first image;

selecting a set of points proximate to said sampled points;

sampling one or more points of said second image; and

modifying said set of points of said first image in accordance with the appearance value of said points sampled from said second image.

56. A method according to claim 55, wherein said step of selecting a set of points proximate to said sampled points comprises selecting a spatially proximate set of points.

57. A method according to claim 55, wherein said step of selecting comprises selecting a set of points having proximate color values.

58. A method according to claim 57, wherein the step of selecting comprises selecting a set of spatially contiguous points having proximate color values.

49. A picture correction apparatus comprising:

an image data file containing a collection of standard description appearance value data representing one or more pictures wherein appearance value data are values that represent color and that are RGB values or values that may be obtained by a reversible transformation or RGB values;

means for modifying appearance value data of a picture so that said picture has an overall visual impression comparable to that of a reference picture when displayed;

means for transforming appearance value data into colorant values capable of transforming appearance value data of said reference picture into colorant values that will print acceptably according to a predetermined standard.

50. A picture correction apparatus according to claim 49, wherein said image data file is compatible with image data derived from different sources and wherein said colorant values are in a standard format and said means for transforming is configured for a specific type of print engine to print correctly according to a predetermined standard

59. A method for reproducing an original color image in a desired state with a color reproduction system comprising the steps of:

displaying an original image on a display device, wherein said original image is represented by original image appearance values, wherein a visual impression of said displayed original image is not constrained to match, according to a predetermined standard for matching visual impression, a visual impression of the original image and is not constrained to match, according to a predetermined standard for matching visual impression, a visual impression of the original image when printed using colorant values converted from said original image appearance values, and wherein appearance values are values that represent color and that are RGB values or values that may be obtained by a reversible transformation of RGB values;

displaying a reference image on a display device, wherein said reference image is represented by reference image appearance values, wherein there is a known relationship between said reference image appearance values and a corresponding set of colorant values that would print an image with a predetermined visual impression, wherein said relationship is defined by a predetermined transformation, and wherein a visual impression of said displayed reference image is not constrained to match, according to a predetermined standard for matching visual impression, said predetermined visual impression; and

adjusting said original image appearance values such that the visual impression of the display of said adjusted original image appearance values matches the visual impression of said displayed reference image, according to a predetermined standard for matching visual impression.

60. A method for reproducing an original color image in a desired state according to claim 59, wherein said step of displaying an original image and said step of displaying a reference image are on the same display device.

61. A method for reproducing an original color image in a desired state according to claim 60, further comprising the step of:

converting said adjusted original image appearance values to colorant values by subjecting said adjusted original image appearance values to said predetermined transformation.

62. An image processing system comprising:

means for receiving a first plurality of appearance values representing a first color image wherein appearance values are values that represent color and that are RGB values or values that may be obtained by a reversible transformation of RGB values;

means for receiving a second plurality of appearance value representing a reference color image;

a display device coupled to said means for receiving a first plurality of appearance values and coupled to said means for receiving a second plurality of appearance values;

means for varying at least a subset of appearance values in said first plurality of appearance values such that a modified first plurality of appearance values is created;

means for converting an appearance value to a colorant value, said means for converting being responsive to said modified first plurality of appearance values.

63. An image processing system according to claim 62 wherein said first color image and said reference color image are displayed on said display device using said first plurality of appearance values and said second plurality of appearance values respectively;

wherein said means for receiving a first plurality of appearance values comprises at least an image storing device;

wherein said means for receiving a second plurality of appearance values comprises at least an image storing device; and

wherein said means for varying is used to vary said subset of appearance values to cause a visual impression of said color image on said display device to match a visual impression of said reference color image on said display device.

64. An image processing system according to claim 63 wherein said means for converting is coupled to said means for receiving a first plurality of appearance values and said means for varying.

65. An image processing system according to claim 63 wherein said means for converting converts said second plurality of appearance values to colorant values which would print an image of said reference color image with a predetermined visual impression.

66. An image processing system for editing a color image, said system comprising:

a display device;

means for generating and displaying on said display device a plurality of varied images of a color image from a first plurality of appearance values which represent said color image, said means for generating and displaying coupled to said display device and wherein appearance values are values that represent color and that are RGB values or values that may be obtained by a reversible transformation or RGB values;

means for selecting one of said plurality of varied images, said one of said plurality of varied images having an associated modification of at least a subset of appearance values in said first plurality of appearance values and said means for selecting is coupled to said means for generating and displaying, said associated modification providing a modified first plurality of appearance values;

means for converting said modified first plurality of appearance values into a corresponding plurality of colorant values.