Compression of image regions according to graphics command type

• US 20060093230A1
• Filed: 10/29/2004
• Published: 05/04/2006
• Est. Priority Date: 10/29/2004
• Status: Active Grant

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Hochmuth, Roland M., Marks, John, Pinedo, David
• Granted Patent: US 7,903,119 B2
• Time in Patent Office: Days
• US Class Current: 382/239
• CPC Class Codes: H04N 1/3333 during transmission, input or output of the picture signal; within a single document or page
• CPC Class Codes: H04N 1/642 Adapting to different types of images, e.g. characters, graphs, black and white image portions
• CPC Class Codes: H04N 19/12 Selection from among a plurality of transforms or standards, e.g. selection between discrete cosine transform [DCT] and sub-band transform or selection between H.263 and H.264
• CPC Class Codes: H04N 19/17 the unit being an image region, e.g. an object
• CPC Class Codes: H04N 19/46 Embedding additional information in the video signal during the compression process H04N19/517, H04N19/68, H04N19/70 take precedence
• CPC Class Codes: H04N 2201/3242 of processing required or performed, e.g. for reproduction or before recording H04N2201/3256 and subgroups take precedence
• CPC Class Codes: H04N 2201/3243 of type information, e.g. handwritten or text document
• CPC Class Codes: H04N 2201/33357 Compression mode

Abstract

A method according to the invention conserves host system resources by compressing an image region according to the type of graphics command used to generate or modify the region. As an image is being rendered, a list of modified image regions is maintained. For each modified image region, metadata are associated with the region to identify the type of graphics command that was used to produce the modification. Per-region choices of compression algorithms can then be made responsive to the metadata without regard to the content of the image data itself.

Claims

1. A method of processing a region that contains image data, the method comprising:

accessing metadata associated with the region, the metadata indicating a type of graphics command that was used to generate or modify the image data;

determining whether the type of graphics command satisfies at least one predetermined criterion; and

if the type of graphics command satisfies the at least one predetermined criterion, choosing a compression algorithm for the region without regard to the content of the image data itself.

2. The method of claim 1, further comprising:

if the type of graphics command does not satisfy the at least one predetermined criterion, choosing a compression algorithm for the region based at least in part on the content of the image data itself.

3. The method of claim 1, wherein:

the at least one predetermined criterion includes whether the graphics command type was a fill command type.

4. The method of claim 1, wherein:

the at least one predetermined criterion includes whether the graphics command type was a text command type.

5. The method of claim 1, wherein:

the at least one predetermined criterion includes whether the graphics command type was a line command type.

6. The method of claim 1, wherein:

the at least one predetermined criterion includes whether the graphics command type was a bitmap command type.

7. The method of claim 6, wherein:

the at least one predetermined criterion includes whether the bitmap command type involved not more than two colors.

8. The method of claim 1, wherein:

choosing a compression algorithm for the region comprises choosing a lossless compression algorithm.

9. The method of claim 8, wherein:

the lossless compression algorithm is a run-length algorithm.

10. The method of claim 8, wherein:

the lossless compression algorithm is a rise-run-length algorithm.

11. The method of claim 8, wherein:

the lossless compression algorithm is a hextile algorithm.

12. A method of processing computer graphics data, comprising:

accessing a graphics command from a stream of graphics commands;

identifying a first region that the graphics command will modify;

creating or locating a first metadata record for the first region;

storing in the first metadata record an indication of a type of the graphics command;

choosing a compression algorithm responsive to information in the first metadata record; and

compressing contents of the first region using the compression algorithm.

13. The method of claim 12, further comprising:

sending the compressed contents to a remote host with an indicator for identifying the compression algorithm or a corresponding decompression algorithm.

14. The method of claim 12, wherein:

accessing the graphics command comprises sending the graphics command to a mirror driver in addition to a graphics driver.

15. The method of claim 14, wherein:

storing the indication in the first metadata record is performed by the mirror driver.

16. The method of claim 12, wherein:

accessing the graphics command comprises intercepting the graphics command with a command wrapper.

17. The method of claim 16, wherein:

storing the indication in the first metadata record is performed by the command wrapper.

18. The method of claim 12, wherein:

choosing the compression algorithm responsive to information in the first metadata record comprises determining whether the graphics command satisfies at least one predetermined criterion.

19. The method of claim 18, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was fill.

20. The method of claim 18, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was text.

21. The method of claim 18, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was line.

22. The method of claim 18, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was bitmap.

23. The method of claim 22, wherein:

the at least one predetermined criterion includes whether the bitmap command type involved not more than two colors.

24. The method of claim 12, further comprising:

accessing a second metadata record for a second region;

responsive to information contained in the first and second metadata records, determining whether graphics commands used to create or modify the first and second regions satisfy at least one predetermined criterion;

if so, identifying an aggregated region that includes at least portions of the first and second regions, the aggregated region having an area larger than an area of the first region; and

compressing contents of the aggregated region using the compression algorithm.

25. Program code embodied in a storage or transmission medium that, when executed on a computer, causes the computer to perform a method of processing a region that contains image data, the method comprising:

accessing metadata associated with the region, the metadata indicating a type of graphics command that was used to generate or modify the image data;

determining whether the type of graphics command satisfies at least one predetermined criterion; and

if the type of graphics command satisfies the at least one predetermined criterion, choosing a compression algorithm for the region without regard to the content of the image data itself.

26. The program code of claim 25, wherein the method further comprises:

if the type of graphics command does not satisfy the at least one predetermined criterion, choosing a compression algorithm for the region based at least in part on the content of the image data itself.

27. The program code of claim 25, wherein:

the at least one predetermined criterion includes whether the graphics command type was a fill command type.

28. The program code of claim 25, wherein:

the at least one predetermined criterion includes whether the graphics command type was a text command type.

29. The program code of claim 25, wherein:

the at least one predetermined criterion includes whether the graphics command type was a line command type.

30. The program code of claim 25, wherein:

the at least one predetermined criterion includes whether the graphics command type was a bitmap command type.

31. The program code of claim 30, wherein:

the at least one predetermined criterion includes whether the bitmap command type involved not more than two colors.

32. The program code of claim 25, wherein:

choosing a compression algorithm for the region comprises choosing a lossless compression algorithm.

33. The program code of claim 32, wherein:

the lossless compression algorithm is a run-length algorithm.

34. The program code of claim 32, wherein:

the lossless compression algorithm is a rise-run-length algorithm.

35. The program code of claim 32, wherein:

the lossless compression algorithm is a hextile algorithm.

36. A computer system configured to process computer graphics data, comprising:

logic for accessing a graphics command from a stream of graphics commands;

logic for identifying a first region that the graphics command will modify;

logic for creating or locating a first metadata record for the first region;

logic for storing in the first metadata record an indication of a type of the graphics command;

logic for choosing a compression algorithm responsive to information in the first metadata record; and

logic for compressing contents of the first region using the compression algorithm.

37. The computer system of claim 36, wherein:

the logic for choosing the compression algorithm responsive to information in the first metadata record comprises logic for determining whether the graphics command satisfies at least one predetermined criterion.

38. The computer system of claim 37, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was fill.

39. The computer system of claim 37, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was text.

40. The computer system of claim 37, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was line.

41. The computer system of claim 37, wherein:

the at least one predetermined criterion includes whether the type of the graphics command was bitmap.

42. The computer system of claim 41, wherein:

the at least one predetermined criterion includes whether the bitmap command type involved not more than two colors.