Digital camera device providing improved methodology for rapidly taking successive pictures

• US 7,847,833 B2
• Filed: 05/06/2008
• Issued: 12/07/2010
• Est. Priority Date: 02/07/2001
• Status: Expired due to Fees

• Current Assignee: RPX Corporation
• Original Assignee: VeriSign, Inc.
• Inventors: Bodnar, Eric, Easwar, Venkat
• Primary Examiner(s): NGUYEN, LUONG TRUNG
• Application Number:
  US12/116,179
• Publication Number:
  US 20080239093A1
• Time in Patent Office: 945 Days
• Field of Search: None
• US Class Current: 348/222.1
• 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:

capturing a sequence of digital images;

applying a first fast compression technique to the sequence of digital images to temporarily compress at least one of the digital images from the sequence of digital images upon capture;

storing the sequence of digital images in an image buffer, wherein the at least one of the digital images is compressed with the first fast compression technique;

deferring a second, thorough compression technique to a period of time when a user is not providing additional input to the digital camera device; and

at the period of time, decompressing the at least one of the digital images that were temporarily compressed and applying the second, thorough compression technique, on a low-priority thread subordinate to a high-priority thread to the entire sequence of digital images after tasks in the high-priority thread have been processed in a multi-threaded execution environment of the digital camera device.

2. The method of claim 1, wherein first fast compression technique requires fewer processing resources for completion than the second, thorough compression technique.

3. The method of claim 1, wherein the digital camera device supports multithreaded execution and applying the second, thorough compression technique occurs as a background execution thread.

4. The method of claim 1, wherein the digital camera device supports multithreaded execution and applying the first fast compression technique occurs as a higher-priority thread.

5. The method of claim 1, wherein the sequence of digital images comprises a series of images captured in rapid succession.

6. The method of claim 1, further comprising:

deleting a digital image, after the digital image is temporarily compressed and the temporarily compressed digital image is stored in the image buffer.

7. The method of claim 1, further comprising after a given digital image is temporarily compressed:

storing a compressed file of the given digital image in a RAM buffer, and

transferring the compressed file from the RAM buffer to flash memory.

8. The method of claim 7, wherein the compressed file is transferred when the RAM buffer is nearly exhausted.

9. 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.

10. The method of claim 9, wherein the pre-compression comprises selected ones of noise smoothing and de-mosaicing.

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

an image capturing system for capturing a series of digital images to an image buffer;

a first rapid compression module for temporarily compressing at least some of the series of digital images upon capture, thereby freeing up available storage in the image buffer;

a decompression module to decompress the temporarily compressed digital images; and

a second thorough compression module for deferring a relatively-thorough compression to a period of time when a user is not providing additional input and compressing the at least some of the series of digital images more thoroughly than that provided by the first rapid compression module at the period of time, wherein the compression of the at least some of the series of digital images more thoroughly occurs in a low-priority thread subordinate to a high-priority thread after tasks in the high-priority thread have been processed in a multi-threaded execution environment of the digital camera device.

12. The digital camera device of claim 11, wherein the first rapid compression module employs a relatively-fast compression technique that requires fewer processing resources for completion than the second thorough compression module.

13. The digital camera device of claim 11, wherein the digital camera device supports multithreaded execution and wherein the second thorough compression module employs a compression technique that operates as a background execution thread.

14. The digital camera device of claim 11, wherein the at least some of the series of digital images comprises successive pictures rapidly captured at the digital camera device.

15. The digital camera device of claim 11, further comprising:

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

16. The digital camera device of claim 11, wherein a digital image is deleted from the image buffer, after the digital image is temporarily compressed and the temporarily compressed digital image is stored in the image buffer.

17. The digital camera device of claim 11, wherein the first rapid compression module further includes a module to apply pre-compression to an image captured as a luminosity record, in preparation for compression.

18. The digital camera device of claim 17, wherein the pre-compression comprises selected ones of noise smoothing and de-mosaicing.