Generating one or more linear blends

• US 20040012617A1
• Filed: 06/11/2003
• Published: 01/22/2004
• Est. Priority Date: 06/17/2002
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Puckett, Giles, Beaumont, Ian Richard
• Granted Patent: US 7,304,648 B2
• Time in Patent Office: Days
• US Class Current: 345/690
• CPC Class Codes: G06T 11/40 Filling a planar surface by adding surface attributes, e.g. colour or texture

Abstract

A method (1005) generates one or more linear blends. Initially, the method has a list of already received one or more fill-paths defining a current linear blend, and a newly received fill-path, where the fill-paths each comprise a single colored parallelogram (eg. 700). The method adds (1090) the new fill-path to the list to become the last fill-path in the list, if the difference (1230) in color between the new fill-path and the last fill-path in the list is no greater, in each color channel, than a predetermined threshold value multiplied by the difference in color between the last and second-last fill-paths in the list. The predetermined threshold value is preset to such a value so that the new fill-path will not be added to the list if the new fill-path does not visually form part of the current linear blend. The method repeats this step for each new fill-path received until the aforementioned condition is not satisfied. Then, the method generates (1040) one or more linear blends from the first fill-path in the list to the last fill-path in the list.

Claims

1. A method of generating one or more linear blends from a list of one or more fill-paths defining a current linear blend, and at least one new fill-path, where the fill-paths each comprise a single colored parallelogram, the method comprising the steps of:

(a) adding one said new fill-path to said list to become a last fill-path in said list, if each condition of a set thereof is met, otherwise proceeding to step (c), said set comprising at least one condition, said one condition being based on the color of the new fill-path and the last fill-path and a threshold value, and said threshold value is preset to such a value so that the new fill-path will not be added to the list if the new fill-path does not visually form part of the current linear blend;

(b) repeating said step (a) for each remaining said new fill-path; and

(c) generating one or more linear blends from the first fill-path in said list to the last fill-path in said list.

2. A method according to claim 1, wherein said one condition comprises:

a difference in color between said new fill-path and the last fill-path in said list being no greater, in each color channel, than the threshold value.

3. A method according to claim 2, wherein said threshold value is two times the difference in color between the last and second-last fill-paths in said list.

4. A method according to claim 1, wherein said set of conditions further comprises:

a (second) condition that the new fill-path is physically contiguous or overlapping with the last fill-path in the list.

5. A method according to claim 1, wherein said set of conditions further comprises:

a (third) condition that a height of said new fill-path is no greater than two times a height of the most recently added fill-path in said list, said height being measured in a direction determined by physical positions of the fill-paths of said list.

6. A method according to claim 1, wherein said set of conditions further comprises:

a (fourth) condition that the number of fill-paths in the current linear blend is greater than 1.

7. A method according to claim 1, wherein said set of conditions further comprises:

a (fifth) condition that a sum of the accumulated height of the fill-paths in said linear blend and a rectangle-height of said new fill-path is less than a predefined maximum.

8. A method according to claim 7 wherein said predefined maximum is set such that the fill does not extend beyond a boundary of an output medium.

9. A method according to claim 1, wherein said set of conditions further comprises:

a (sixth) condition that a raster operation for the currently received fill-path does not use a destination, and is the same as a raster operation for the current linear blend.

10. A method according to claim 1, wherein said set of conditions further comprises:

a (seventh) condition that the currently received fill-path has the same clip as the current linear blend.

11. The method according to claim 1, wherein said list comprises an original list of fill-paths[1] . . . [n], and said generating step (c) comprises the sub-steps of:

(ca) determining if the color gradient between fill-path[1] and fill-path[n] of the list is equal within a predetermined error tolerance to the color gradient between fill-path[1] and fill-path[n/2] of the list; and

(caa) if so, outputting a linear blend for the list of fill-paths [1] . . . [n], from the color and position of the first fill-path in said list to the color and position of the last fill-path in said list;

otherwise

(cab) partitioning the list of fill-paths [1] . . . [n] into two lists of at least substantially equal number of fill-paths; and

(cb) repeating step (ca) for each partitioned list, until all fill-paths in the original list of fill-paths [1] . . . [n] have been processed.

12. A method according to claim 11 wherein step (cab) comprises partitioning said list into two lists, one for a first half of the list (fill-path[1] . . . fill-path[n/2]) and one for a second half of the list (fill-path[n/2] . . . fill-path[n]).

13. A method according to claim 11 wherein step (cab) comprises partitioning said list into two lists, one for a first half of the list (fill-path[1] . . . fill-path[n/2]) and one for a second half of the list (fill-path[(n/2)+1] . . . fill-path[n]).

14. A method according to claim 11, wherein a second linear blend corresponding to a second partitioned list of fill-paths is output adjacent a first linear blend corresponding to a first partitioned list of fill-paths, wherein an initial color of the second linear blend is set to a final color of the first linear blend.

15. A method according to claim 1 wherein said list defining said current linear blend relates to one or more already received fill-paths and said at least one new fill-path is newly received to thereby enable implemention of said method.

16. A method according to claim 4 wherein a contiguity between said fill-paths is determined by at least comparing the alignment thereof.

17. A computer program element comprising computer program code means to make a computer execute a procedure generate one or more linear blends from a list of one or more fill-paths defining a current linear blend, and at least one new fill-path, where the fill-paths each comprise a single colored parallelogram, the program code means comprising

adding code means for adding one said new fill-path to said list to become a last fill-path in said list, if each condition of a set thereof is met, otherwise executing said generation code means, wherein said set comprises at least one condition, said one condition being based on the color of the new fill-path and the last fill-path and a threshold value, and said threshold value is preset to such a value so that the new fill-path will not be added to the list if the new fill-path does not visually form part of the current linear blend;

code means for calling said adding code means for each remaining said new fill-path; and

generating code means for generating one or more linear blends from the first fill-path in said list to the last fill-path in said list.

18. A computer program element according to claim 17, wherein said one condition comprises:

a difference in color between said new fill-path and the last fill-path in said list being no greater, in each color channel, than the threshold value.

19. A computer program element according to claim 18, wherein said threshold value is two times the difference in color between the last and second-last fill-paths in said list.

20. A computer program element according to claim 17, wherein said set of conditions further comprises conditions selected from the group consisting of:

a (second) condition that the new fill-path is physically contiguous or overlapping with the last fill-path in the list;

a (third) condition that a height of said new fill-path is no greater than two times a height of the most recently added fill-path in said list, said height being measured in a direction determined by physical positions of the fill-paths of said list;

a (fourth) condition that the number of fill-paths in the current linear blend is greater than 1;

a (fifth) condition that a sum of the accumulated height of the fill-paths in said linear blend and a rectangle-height of said new fill-path is less than a predefined maximum;

a (sixth) condition that a raster operation for the currently received fill-path does not use a destination, and is the same as a raster operation for the current linear blend; and

a (seventh) condition that the currently received fill-path has the same clip as the current linear blend.

21. A computer program element according to claim 20 wherein said predefined maximum of said fifth condition is set such that the fill does not extend beyond a boundary of an output medium.

22. A computer program element according to claim 17, wherein said list comprises an original list of fill-paths[1] . . . [n], and said generating code means comprises:

code means for determining if the color gradient between fill-path[1] and fill-path[n] of the list is equal within a predetermined error tolerance to the color gradient between fill-path[1] and fill-path[n/2] of the list; and

if so, code means for outputting a linear blend for the list of fill-paths [1] . . . [n], from the color and position of the first fill-path in said list to the color and position of the last fill-path in said list;

otherwise

code means for partitioning the list of fill-paths [1] . . . [n] into two lists of at least substantially equal number of fill-paths; and

code means for calling said code means for determining for each partitioned list, until all fill-paths in the original list of fill-paths [1] . . . [n] have been processed.

23. A computer program element according to claim 22 wherein said code means for partitioning partitions said list into two lists, one for a first half of the list (fill-path[1] . . . fill-path[n/2]) and one for a second half of the list (fill-path[n/2] . . . fill-path[n]).

24. A computer program element according to claim 22 wherein said code means for partitioning partitions said list into two lists, one for a first half of the list (fill-path[1] . . . fill-path[n/2]) and one for a second half of the list (fill-path[(n/2)+1] . . . fill-path[n]).

25. A computer program element according to claim 22, wherein a second linear blend corresponding to a second partitioned list of fill-paths is output adjacent a first linear blend corresponding to a first partitioned list of fill-paths, wherein an initial color of the second linear blend is set to a final color of the first linear blend.

26. A computer program element according to claim 17 wherein said list defining said current linear blend relates to one or more already received fill-paths and said at least one new fill-path is newly received to thereby enable execution of program element.

27. A computer program element according to claim 17 wherein said element comprises part of a graphical device interface.

28. A computer program element according to claim 20 wherein a contiguity between said fill-paths is determined by at least comparing the alignment thereof.

30. A computer readable medium comprising a computer program element according to claim 17

29. Apparatus for generating one or more linear blends from a list of one or more fill-paths defining a current linear blend, and at least one new fill-path, where the fill-paths each comprise a single colored parallelogram, said apparatus comprising:

means for adding one said new fill-path to said list to become a last fill-path in said list, if each condition of a set thereof is met, otherwise enabling a generating means, said set comprising at least one condition, said one condition being based on the color of the new fill-path and the last fill-path and a threshold value, and said threshold value is preset to such a value so that the new fill-path will not be added to the list if the new fill-path does not visually form part of the current linear blend;

means for repeating operation of said adding means for each remaining said new fill-path; and

said generating means being operable to generate one or more linear blends from the first fill-path in said list to the last fill-path in said list.