Color processing system

• US 5,963,201 A
• Filed: 09/09/1996
• Issued: 10/05/1999
• Est. Priority Date: 05/11/1992
• Status: Expired due to Term

• Current Assignee: Apple Inc.
• Original Assignee: Apple Computer Incorporated (Apple Inc.)
• Inventors: Brink, David Van, Yerga, Christopher M., McGreggor, Keith
• Primary Examiner(s): Huynh, Ba
• Application Number:
  US08/711,082
• Time in Patent Office: 1,121 Days
• Field of Search: 345/326, 345/88, 345/186, 345/431
• US Class Current: 715/722
• CPC Class Codes: H04N 1/603 controlled by characteristics of the picture signal generator or the picture reproducer
• CPC Class Codes: H04N 1/6058 Reduction of colour to a range of reproducible colours, e.g. to ink- reproducible colour gamut

Abstract

A system for processing color information is based on carrying with color data, an indicator of the color space in which the data is represented. In this manner, the system is enabled to process color data from a variety of sources independent of the color space of the sources, because it is able to respond to the color space of a particular color value perform the necessary transformations to operate within any other arbitrary color and color space combination. The system provides for manipulating or combining colors independent of the source and destination color spaces. Also, the system operates on a per color component basis in user selected working color space, independent of the color space of the input or destination devices.

Claims

1. A method for processing color information in a computer system, comprising:

specifying in a first memory location a source color in a color data structure;

the color data structure including a colorspace field, a colorset field, a colorprofile field and a color data field, the color data structure being arranged to store color data associated with a source color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the source color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space;

the color data structure including a source color space parameter set identifying the source color space and source color data indicating components in the source color space, the source color space being user selected from a set of color spaces;

specifying in a second memory location a destination color in a data structure including a destination color space parameter set identifying a destination color space, the destination color space being user selected from the set of color spaces; and

computing with a processor coupled to the first and second memory locations a resultant color data structure in response to the source color data, the source color space parameter set and the destination color space parameter set, the resultant color data structure including resultant color data indicating components in the destination color space.

2. The method of claim 1, wherein the step of computing includes:

first converting in response to the source color space parameter set with the processor the source color data structure into a working color data structure having working color data indicating components in a working color space and storing the working color data structure in a working memory; and

second converting with the processor the working color data structure into the resultant color data structure.

3. The method of claim 1, wherein the step of computing includes:

providing to the processor a color operator specifying a function and executing the function.

4. The method of claim 3, wherein the color operator specifies a working color space, and the step of executing the function includes:

first converting with the processor the source color data structure into a working color data structure having working color data indicating components in the working color space and storing the working color data structure in a working memory;

operating with the processor on the working color data in the working memory; and

second converting with the processor the working color data structure into the resultant color data structure.

5. The method of claim 4, wherein the operator specifies functions which operate on a per component basis in the working color space.

6. The method of claim 3, wherein the operator specifies functions which operate on a per component basis.

7. The method of claim 1, wherein the source color space parameter set and destination color space parameter set include a first member identifying a data packing format and a second member identifying an algorithmic color space.

8. The method of claim 1, wherein the source color is stored in an algorithmic color space and the contents of the colorset field is nil.

9. The method of claim 1, wherein the colorspace field also contains color packing data.

10. The method of claim 1, wherein the color profile field contains an indication of the primary colorants within the color space, tonal reproduction curves and matching flags.

11. The method of claim 1, wherein the source color is stored in an indexed color space and the contents of the colorspace field contains the index.

12. The method of claim 11, wherein the source color is stored in an indexed color space and the contents of the colorprofile field is nil.

13. The method of claim 1, wherein the source color is converted from an indexed to an algorithmic color space.

38. The method of claim 1, further including:

producing on a destination color graphics device a resultant color in response to the resultant color data.

14. A computer operating system for processing color data to produce a resultant color on a destination color graphics device, comprising:

a memory to store at least one color data structure;

the color data structure including a colorspace field, a colorset field, a colorprofile field and a color data field, the color data structure being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the color space is an indexed color space, and the colorprofile field con contain a characterization of the color space;

the color data structure having data identifying a color including a color space parameter set identifying a color space, the color space being user selected from a set of color spaces, and component data indicating components of the color in the color in the color space;

color processing means, coupled to the memory and responsive to the at least one color data structure in the memory and a destination color space, the destination color space being user selected from the set of color spaces, for the destination color graphics device, for generating resultant color data indicating components of the resultant color in the destination color space.

15. The system of claim 14, wherein the color space parameter set includes a color profile, including components of primary colorants in the color space of the color data structure.

16. The system of claim 15, wherein the color profile further includes tonal reproduction curves for colorants of color graphic devices.

17. The system of claim 14, wherein the color space identified in the at least one color data structure is selected from a set of color spaces, and the set of color spaces includes a first subset of algorithmic color spaces, wherein the color component data of the algorithmic color spaces includes the components within a color coordinate system of a color of the algorithmic color spaces, and a second subset of indexed color spaces, wherein the color component data of the indexed color spaces includes a pointer to an entry in a list where entries in the list comprise color components within a color coordinate system of respective colors of the indexed color spaces.

18. The system of claim 14, wherein the resultant color data of said color processing means comprises a resultant color data structure including data identifying the destination color space and the resultant color data.

19. The system of claim 14, wherein the color processing means includes:

a color matching module, coupled to the memory, to generate resultant color data which results in a color in the destination color space which substantially matches the color identified by the color data structure.

20. The system of claim 14, wherein the memory stores at least a first color data structure and a second color data structure, and the color processing means includes:

color combining means, coupled to the memory and responsive to the color component data of the first color data structure and of the second color data structure, for generating the resultant color data as a function of the components of the first and second colors.

21. The system of claim 20, wherein the second color data structure includes data which identifies a color currently displayed on the destination device.

22. The system of claim 20, wherein the color combining means includes:

first converting means for converting the first color data structure and the second color data structure into respective first and second working color data in a common working color space indicating components in the working color space of the respective colors identified by the first and second color data structures;

means for operating on the first and second working color data to generate intermediate color data indicating components in the working color space of a resultant color; and

second converting means for converting the intermediate color data into the resultant color data.

23. The system of claim 22, wherein the means for operating is responsive to operators specifying functions for combining the first and second working color data on a per component basis.

24. The system of claim 14, wherein the color space parameter set of the at least one color data structure further includes data identifying a data packing format.

25. The system of claim 20 wherein the destination device has a destination store for storing color data in a data packing format, and the color combining means includes:

first converting means for converting the first color data structure and the second color data structure into respective first and second working color data in a common working color space with a common data packing format indicating components in the working color space of the respective colors identified by the first and second color data structures;

means for operating on the first and second working color data to generate intermediate color data indicating components in the working color space of a resultant color; and

second converting means for converting the intermediate color data into the resultant color data in the data packing format of the destination device.

26. The system of claim 24, wherein the destination device has a destination store for storing color data in a data packing format independent of the data packing format of the at least one color data structure, and the color processing means includes:

means for packing the resultant color data in the data packing format of the destination device.

39. The system of claim 14, further including:

a destination interface, coupled to the color processing means, to supply the resultant color data to the destination device to produce the resultant color.

27. A system for combining first color data identifying a first color, the first color data including components of the color in a first color space, with second color data identifying a second color, the second color data including components of the second color in a second color space, to generate resultant data identifying a resultant color in a resultant image, comprising:

memory to store the first and second color data, the first and second data structure arranged into first and second color data structures, the first and second color data structures including a colorspace field, a colorset field, a colorprofile field and a color data field, the color data structures being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space;

first converting means coupled to the memory for converting the first color data identifying the first color in the first color space and the second color data identifying the second color in the second color into first and second working color data identifying components of the first and second colors in a common working color space, wherein the first and second color spaces are different;

means, coupled to the first converting means, for operating on the first and second working color data to generate intermediate color data indicating components in the working color space of a resultant color; and

second converting means, coupled to the means for operating, for converting the intermediate color data into the resultant color data for the resultant image.

28. The system of claim 27, wherein the means for operating includes:

means, coupled to the memory, for testing the first working color data to determine whether a component of the first color satisfies a range condition; and

means, responsive to the means for testing, for conditionally affecting the means for operating.

29. The system of claim 27, wherein the means for operating includes:

first means, coupled to the memory, for testing the first working color data to determine whether a component of the first color satisfies a first range condition;

second means, coupled to the memory, for testing the second working color data to determine whether a component of the second color satisfies a second range condition; and

means, responsive to the first and second means for testing, for conditionally affecting the means for operating.

30. The system of claim 27, wherein the means for operating includes:

means, coupled to the first converting means, for testing the intermediate working color data to determine whether a component of the resultant color satisfies a range condition; and

means, responsive to the means for testing, for conditionally altering the intermediate working color data.

31. The system of claim 27, wherein the means for operating includes:

a control input store to store a function code and to store first and second matrices of control parameters;

first means, coupled to the control input store and responsive to the first matrix, for filtering the first working color data to generate first filtered data;

second means, coupled to the control input store and responsive to the second matrix, for filtering the second working color data to generate second filtered data; and

means, coupled to the first means, second means, and control input store responsive to a function code, for combining the first and second filtered data to generate the intermediate working color data.

32. The system of claim 31, wherein the first and second matrices include a scale factor for each component of the respective first and second working color data.

33. The system of claim 32, wherein the first and second matrices include an offset factor for each component of the respective first and second working color data.

34. The system of claim 27, wherein the means for operating includes:

a control input store to store an output matrix of control parameters; and

means, coupled to the control input store and responsive to the output matrix, for filtering the intermediate working color data.

35. The system of claim 34, wherein the output matrix includes a scale factor for each component of the intermediate working color data.

36. The system of claim 35, wherein the output matrix includes an offset factor for each component of the intermediate working color data.

37. The system of claim 27, wherein the second means for converting converts the intermediate data into data indicating components of the resultant color in the second color space.

40. The system of claim 27, further including:

a destination interface, coupled to the second converting means, to supply the resultant data to a destination device to produce the resultant image.

41. A computer-implemented method of processing a color graphic image comprising the steps of:

generating color data in a first device-dependent color space, said color data representing colors in a color graphic image;

arranging the color data into a color data structure, the color data structures including a colorspace field, a colorset field, a colorprofile field and a color data field, the color data structures being arranged to store color data associated with a color space which may be one on a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space; and

the colorprofile field can contain a characterization of the color space; and

wherein the color data structure contains an indication of the device-dependent color space, the use of the color data structure enabling there to be derived corresponding colors in a device-independent color space, corresponding to the colors in the color graphic image; and

processing said color data using said color space data.

42. A color processing system comprising:

means for generating color data in a first device-dependent color space, said color data representing colors in a color graphic image;

means for arranging the color data into a color data structure, the color data structures including field, a colorset field, a colorprofile field and a colordata field, the color data structures being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space; and

wherein the color data structure contains an indication of the device-dependent color space, the use of the color data structure enabling there to be derived corresponding colors in a device-independent color space, corresponding to the colors in the color graphic image; and

means for processing said color data using said color space data.

43. A computer-readable medium containing program instructions for:

arranging the color data into a color data structure, the color data structures including a colorspace field, a colorset field, a colorprofile field and a colordata field, the color data structures being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space; and

wherein the color data structure contains an indication of the device-dependent color space, the use of the color structure enabling there to be derived corresponding colors in a device-independent color space, corresponding to the colors in the color graphic image; and

processing said color data using said color space data.

44. A computer-implemented method of processing a color graphic image comprising the steps of:

a user specifying at least one color graphic image represented by color data in a first color space, an operation to be performed on the color graphic image, and a working color space in which the operation is to be performed, the color data of the color graphic image being arranged into a color data structure, the color data structures including a colorspace field, a colorset field, a colorprofile field and a color data field, the color data structures being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space; and

performing the operation in the working color space;

wherein the working color space is different from the first color space.

45. A color processing system comprising:

means for a user to specify at least one color graphic image represented by color data in a first color space, an operation to be performed on the color graphic image, and a working color space in which the operation is to be performed, the color data of the color graphic image being arranged into a color data structure, the color data structures including a colorspace field, a colorset field, a colorprofile field and a colordata field, the color data structures being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space; and

means for performing the operation in the working color space;

wherein the working color space is different from the first color space.

46. A computer-readable medium containing program instructions for:

specifying at least one color graphic image represented by color data in a first color space, an operation to be performed on the color graphic image, and a working color space in which the operation is to be performed, the color data arranged into a color data structure, the color data structures including a colorspace field, a colorset field, a colorprofile field and a color data field, the color data structures being arranged to store color data associated with a color space which may be one of a variety of color spaces including algorithmic and indexed color spaces, wherein the colorspace field contains an indication of the color space if the source color space is an algorithmic color space, the colorset field contains an indication of possible indexed colors if the source color space is an indexed color space, and the colorprofile field can contain a characterization of the color space; and

performing the operation in the working color space;

wherein the working color space is different from the first color space.