Method and apparatus for processing image files

• US 6,741,746 B2
• Filed: 02/08/2002
• Issued: 05/25/2004
• Est. Priority Date: 03/17/1999
• Status: Expired due to Term

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Inventors: Nhu, Hoang, Norton, Kirkpatrick William, Epstein, Yoav
• Primary Examiner(s): Wu, Jingge
• Application Number:
  US10/072,245
• Publication Number:
  US 20020085767A1
• Time in Patent Office: 837 Days
• Field of Search: 382/232-246, 382/296-300, 358/261.4, 358/432-451, 348/415--41, 348/458, 345/434-437, 375/240.24
• US Class Current: 382/233
• CPC Class Codes: G06Q 50/08 Construction

Abstract

A method and apparatus for manipulating digitized images stored as variable length encoded bitstreams such as JPEG format in a manner that reduces memory and processor resource requirements. A prescan means sequentially decompresses the bitstream to identify the location of encoded pixel image areas. Designated ones of these locations are recorded or stored in a prescan table. After the prescan operation has been performed on the image, image manipulations such as rotating, cropping, and zooming can be performed on a selected portion of the image by directly accessing only the encoded pixel image areas to be manipulated, without the need to sequentially decode and store all the encoded image areas in order to locate the ones of interest.

Claims

1. A method for processing a variable length encoded binary bitstream collectively indicative of a digitized image, comprising:

sequentially detecting individual ones of a plurality of encoded image areas in the bitstream, each detected one of the plurality of encoded image areas indicative of a region of pixels within the digitized image;

storing location information for designated detected ones of the plurality of encoded image areas, the designated detected ones including fewer than all the detected ones;

decoding at least some of the detected ones of the plurality of encoded image areas; and

wherein each individual ones of the plurality of encoded image areas is indicative of a first rectangular two-dimensional space of uniform size,

wherein the plurality of encoded image areas is indicative of a second rectangular two-dimensional space organized in rows and columns of encoded image areas, and

wherein the designated detected ones of the plurality of encoded image areas are selected such that the column positions are identical for all rows.

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

storing the decoded ones of the encoded image areas to facilitate the manipulation of the digitized image.

3. The method of claim 1, wherein the step of storing further includes storing a calculated absolute coefficient value for the designated detected ones of the plurality of encoded image areas.

4. The method of claim 3, wherein each individual one of the plurality of encoded image areas is a minimal coded unit according to a JPEG format.

5. The method of claim 3, wherein each individual one of the plurality of encoded image areas has a relative coefficient value.

6. The method of claim 1, wherein the location information includes an offset into the bitstream of the start of the encoded image area.

7. The method of claim 4, wherein the digitized image has a plurality of color channels, and each minimal coded unit has a corresponding plurality of relative coefficient values.

8. The method of claim 7, where the step of storing location information includes storing a calculated absolute coefficient value for each color channel of the minimal coded unit.

9. The method of claim 5, wherein the calculated absolute coefficient value is the sum of the relative coefficient values for the sequentially detected individual ones of the plurality of encoded image areas.

10. The method of claim 8, wherein the calculated absolute coefficient value for each color channel is the sum of the relative coefficient values for the color channel.

11. The method of claim 1 wherein the at least some of the detected ones decoded include detected ones for which no location information is stored.

12. The method of claim 1 wherein the decoding further includes using the stored location information to decode at least some detected ones for which no location information is stored.

13. An image processing apparatus, comprising:

prescan means for sequentially detecting individual ones of a plurality of encoded image areas embodied in a variable length encoded bitstream, each detected one of the plurality of encoded image areas indicative of a region of pixels within the digitized image;

decoding means for decoding at least some of the detected ones of the plurality of encoded image areas for image manipulation purposes; and

storage means for storing location information provided by the prescan means for fewer than all the detected ones of the plurality of encoded image areas, and for storing a decoded image area provided by the decoding means for each decoded one of the plurality of encoded image areas, to facilitate manipulation of the digitized image.

14. The apparatus of claim 13, where the prescan means further comprises an application-specific integrated circuit.

15. The apparatus of claim 13, where the prescan means further comprises a microprocessor.

16. The apparatus of claim 13, further comprising image manipulation means coupled to the storage means for manipulating the decoded image areas to form a processed image.

17. The apparatus of claim 16, further comprising an image processing executive coupled to the decoding means for designating the individual ones of the plurality of encoded image areas to be decoded.

18. The apparatus of claim 17, where the image processing executive is further coupled to the image manipulation means for designating an image manipulation operation.

19. The apparatus of claim 13, further comprising a bitstream source coupled to the prescan means and the decoding means for supplying the bitstream.

20. The apparatus of claim 19, where the bitstream source is a scan engine.

21. The apparatus of claim 19, where the bitstream source is a photographic engine.

22. The apparatus of claim 19, where the bitstream source is a facsimile receiver.

23. The apparatus of claim 19, where the bitstream source is a memory interface adapted to receive a mass storage device containing the bitstream.

24. The apparatus of claim 23, where the mass storage device is a memory card.

25. The apparatus of claim 19, where the bitstream source is a network interface adapted to receive the bitstream from a network device.

26. The apparatus of claim 25, where the network device is a computer.

27. The apparatus of claim 16, further comprising a print engine coupled to the image manipulation means for facilitating the printing of the processed image.

28. The apparatus of claim 27, where the print engine is a inkjet printer print engine.

29. The apparatus of claim 28, where the inkjet printer print engine is a thermal inkjet printer print engine.

30. The apparatus of claim 28, where the inkjet printer print engine is a bubble inkjet printer print engine.

31. The apparatus of claim 28, where the inkjet printer print engine is a piezoelectric inkjet printer print engine.

32. The apparatus of claim 16, further comprising a display device coupled to the image manipulation means for facilitating the display of the processed image.

33. The apparatus of claim 32, where the display device is a liquid crystal display.

34. The apparatus of claim 32, where the display device is a cathode ray tube display.