Parallel decode of a progressive JPEG bitstream
A progressive JPEG bitstream may comprise an image component that is comprised of multiple scans of MCUs/data units that are in turn comprised of at least one MCU/data unit segment. Each MCU/data unit segment is successively scanned. The MCU/data unit segment is then reconstructed using multiple entropy decoders operating in parallel on different scans of each MCU/data unit segment.
1. A method of processing an image bitstream, the method comprising:
determining an image in a user's region of interest;
successively scanning a data unit segment of the determined image to produce two or more scans;
decoding, in parallel, the two or more scans of the data unit segments; and
reconstructing the data unit segment according to the two or more decoded scans of the data unit segment, wherein the image in the user's region of interest is reconstructed with a higher image quality.
2. The method of claim 1 , wherein decoding comprises utilizing multiple entropy decoders.
3. The method of claim 1 , wherein the data unit segment is between two synchronization points.
4. The method of claim 1 , wherein decoding comprises temporarily storing a discrete cosine transform (DCT) coefficient of the data unit segment in an output image buffer.
5. The method of claim 1 , wherein the data unit segment comprises ¼ th of frequency coefficients that are present in a top-left 4×4 array of an 8×8 a data unit block.
6. The method of claim 1 , wherein the data unit segment comprises an approximation of at least one image component using stored DCT coefficients.
7. The method of claim 1 , wherein the method comprises up-scaling reconstructed sub-sampled approximations of the data unit segment.
8. The method of claim 1 , wherein the user's region of interest is identified by a user interface.
9. The method of claim 1 , wherein the image is displayed by a set top box.
10. The method of claim 1 , wherein the image is shared over a wireless channel.
11. A system for processing an image bitstream comprising:
a user interface operable to identify an image in a user's region of interest;
a scanner operable to successively scan a data unit segments of the image in the image bitstream to produce two or more scans;
two or more decoders operable in parallel to decode the two or more scans of the data unit segment; and
a circuit operable to reconstruct the data unit segment according to the two or more decoded scans of the data unit segment, wherein the image in the user's region of interest is reconstructed with a higher image quality.
12. The system of claim 11 , wherein the two or more decoders are two or more entropy decoders.
13. The system of claim 11 , wherein the data unit segment is between two synchronization points.
14. The system of claim 11 , wherein the system comprises an output image buffer operable to temporarily store a discrete cosine transform (DCT) of the data unit segment.
15. The system of claim 11 , wherein the data unit segment comprises ¼ th of frequency coefficients that are present in a top-left 4×4 array of an 8×8 a data unit block.
16. The system of claim 11 , wherein the data unit segment comprises an approximation of at least one image component using stored DCT coefficients.
17. The system of claim 11 , wherein the circuit is operable to up-scale reconstructed sub-sampled approximations of the data unit segment.
18. The system of claim 11 , wherein the image is displayed by a set top box.
19. The system of claim 11 , wherein the image is shared over a wireless channel.
20. The system of claim 11 , wherein the image is shared over a wireless local network.