Digital camera device providing improved methodology for rapidly taking successive pictures

• US 20010036231A1
• Filed: 02/07/2001
• Published: 11/01/2001
• Est. Priority Date: 06/08/1999
• Status: Active Grant

• Current Assignee: RPX Corporation
• Original Assignee: VeriSign, Inc.
• Inventors: Bodnar, Eric O., Easwar, Venkat
• Granted Patent: US 7,369,161 B2
• Time in Patent Office: Days
• US Class Current: 375/240.19
• CPC Class Codes: G06T 9/007 Transform coding, e.g. discrete cosine transform
• CPC Class Codes: H04N 1/2112 using still video cameras
• CPC Class Codes: H04N 1/46 Colour picture communication systems
• CPC Class Codes: H04N 1/64 Systems for the transmission or the storage of the colour picture signal; Details therefor, e.g. coding or decoding means therefor H04N19/00 takes precedence
• CPC Class Codes: H04N 2201/3247 Data linking a set of images to one another, e.g. sequence, burst or continuous capture mode

Abstract

An in-camera two-stage compression implementation is described that reduces the latency between snapshots to a fraction of that otherwise required by other systems that either process complete compression following each snapshot or that incorporate heavy, bulky, and expensive RAM hardware capable of maintaining several raw luminosity records (unprocessed file containing a digital image). In the 1st stage compression the raw luminosity record is quickly, yet partially, compressed to available RAM buffer space to allow a user to expeditiously capture a succeeding image. When the higher-priority processes, the user shooting pictures, and stage one compression subside, a 2nd stage compression, which is slower but more effective, decompresses the earlier partially-compressed images, and re-compresses them for saving in flash memory until they are distributed to a remote platform to be finally converted to the JPEG2000 format.

Claims

1. A method for compressing digital images upon capture at a digital camera device, the method comprising:

receiving user input requesting capture of a sequence of digital images at the digital camera device, said digital images being stored in an image buffer;

applying a relatively-fast compression technique to temporarily compress at least some of the digital images upon capture, so as to increase availability of storage in said image buffer for storing other digital images being capture;

at some point in time after cessation of the user input, decompressing any of the digital images that were temporarily compressed; and

thereafter applying a relatively-thorough compression technique to the captured sequence of digital images.

2. The method of

claim 1

, wherein said relatively-fast compression technique requires fewer processing resources for completion than said relatively-thorough compression technique.

3. The method of

claim 1

, wherein said digital camera device supports multithreaded execution and wherein said step of applying a relatively-thorough compression technique occurs as a background execution thread.

4. The method of

claim 3

, wherein said background execution thread comprises a low-priority thread that is executed by a microprocessor of the digital camera device.

5. The method of

claim 1

, wherein said sequence of digital images comprises successive pictures rapidly captured at the digital camera device.

6. The method of

claim 5

, wherein the digital images of the sequence are captured within a few seconds time.

7. The method of

claim 1

, further comprising:

after the digital images have been compressed using the relatively-thorough compression technique, storing the compressed digital images on media.

8. The method of

claim 1

, further comprising:

after the digital images have been compressed using the relatively-thorough compression technique, transferring the compressed digital images to another device.

9. The method of

claim 8

, wherein the compressed images are transferred using wireless communication.

10. The method of

claim 8

, wherein the compressed images are transferred using wireline communication.

11. The method of

claim 1

, wherein said digital camera device supports multithreaded execution and wherein said step of applying a relatively-fast compression technique occurs as a higher-priority thread.

12. The method of

claim 1

, wherein the relatively-thorough compression technique produces a smaller-sized compressed image file for a given digital image than that produced by the relatively-fast compression technique.

13. The method of

claim 1

, wherein the relatively-fast compression technique requires less compression time when compressing a given digital image than that required by the relatively-thorough compression technique.

14. The method of

claim 1

, further comprising:

after a given digital image is temporarily compressed, storing a compressed file of that digital image in a flash memory.

15. The method of

claim 1

, further comprising:

after a given digital image is temporarily compressed, storing a compressed file of that digital image in a RAM buffer.

16. The method of

claim 1

, further comprising:

after a given digital image is temporarily compressed, storing a compressed file of that digital image back in the image buffer.

17. The method of

claim 1

, further comprising:

after a given digital image is temporarily compressed, deleting the given digital image'"'"'s original copy from the image buffer.

18. The method of

claim 1

, further comprising:

after a given digital image is temporarily compressed, performing substeps of;

(1) storing a compressed file of that digital image in a RAM buffer, and

(2) transferring the compressed file from the RAM buffer to flash memory.

19. The method of

claim 18

, wherein said transfer step occurs when the RAM buffer is nearly exhausted.

20. The method of

claim 18

, wherein said transfer step occurs when the user is no longer requesting capture of a sequence of digital images.

21. The method of

claim 1

, wherein latency of the digital camera device is decreased between capturing successive images when the relatively-fast compression technique is employed, as compared to employing the relatively-thorough compression technique.

22. The method of

claim 1

, further comprising:

capturing each digital image as a luminosity record; and

applying pre-compression to each luminosity record, in preparation for compression.

23. The method of

claim 22

, wherein said pre-compression comprises selected ones of noise smoothing and de-mosaic.

24. The method of

claim 1

, wherein said step of applying a relatively-thorough compression technique occurs once the digital camera device has processed all high-priority tasks.

25. The method of

claim 1

, wherein said relatively-fast compression technique includes discrete wavelet transformation.

26. The method of

claim 1

, wherein said relatively-fast compression technique includes quantization.

27. The method of

claim 1

, wherein said relatively-fast compression technique includes low-complexity entropy encoding.

28. The method of

claim 27

, wherein said low-complexity entropy encoding includes run-length encoding.

29. The method of

claim 1

, further comprising:

deferring applying said relatively-thorough compression technique to the digital images during periods of time when the user is providing additional input.

30. The method of

claim 29

, wherein said additional input comprises user input other than that for requesting capture of additional images.

31. The method of

claim 29

, wherein said additional input comprises user input for configuring the digital camera device.

32. The method of

claim 1

, wherein said step of decompressing any of the compressed digital images that were temporarily compressed restores the digital images to their approximate pre-compression state.

33. The method of

claim 1

, wherein said relatively-fast compression technique includes lossy compression technique.

34. The method of

claim 1

, wherein said relatively-thorough compression technique includes lossy compression technique.

35. The method of

claim 1

, wherein said relatively-thorough compression technique includes high-complexity entropy encoding.

36. The method of

claim 1

, wherein each digital image is divisible into separate bit planes and wherein said relatively-fast compression technique includes:

applying compression to individual bit planes of a given digital image undergoing compression.

37. The method of

claim 36

, wherein said decompressing step includes:

decompressing an individual bit plane of a given digital image before decompressing other bit planes of that given digital image.

38. The method of

claim 1

, wherein said relatively-fast compression technique provides about 1:

4 compression.

39. The method of

claim 1

, wherein said relatively-thorough compression technique provides approximately 1:

20 compression.

40. The method of

claim 1

, further comprising:

transmitting the compressed digital images wirelessly for remote processing to a JPEG-compatible format.

41. A digital camera device with improved latency time between acquiring pictures, the device comprising:

a digital camera device for capturing digital images to an image buffer;

a user-activated button, integrated into the digital camera device, for generating a user request to capture a sequence of digital images at the digital camera device, said digital images being stored in the image buffer upon capture;

a first compression module, embodied within the digital camera device, for temporarily compressing at least some of the digital images upon capture, thereby freeing up available storage in said image buffer;

a decompression module, embodied within the digital camera device, for decompressing any of the digital images that were temporarily compressed at some point in time after activation of said user-activated button; and

a second compression module, embodied within the digital camera device, for compressing said digital images more thoroughly than that provided by said first compression module.

42. The device of

claim 41

, wherein said first compression module employs a relatively-fast compression technique that requires fewer processing resources for completion than said relatively-thorough compression technique.

43. The device of

claim 41

, wherein said digital camera device supports multithreaded execution and wherein said first compression module employs a compression technique that operates as a background execution thread.

44. The device of

claim 43

, wherein said background execution thread comprises a low-priority thread that is executed by a microprocessor of the digital camera device.

45. The device of

claim 41

, wherein said sequence of digital images comprises successive pictures rapidly captured at the digital camera device.

46. The device of

claim 45

, wherein the digital images of the sequence are captured within a few seconds time.

47. The device of

claim 41

, wherein the digital images that have been compressed using the second compression module are stored on a media device.

48. The device of

claim 41

, further comprising:

a communication means for transferring the compressed digital images to another device.

49. The device of

claim 48

, wherein the compressed images are transferred using wireless communication.

50. The device of

claim 48

, wherein the compressed images are transferred using wireline communication.

51. The device of

claim 41

, further comprising:

a flash memory for storing a given digital image that has been temporarily compressed.

52. The device of

claim 41

, further comprising:

a RAM buffer for storing a given digital image that has been temporarily compressed.