Patent ID: 8326059

Claim:
A method for decoding an image file storing an image being progressively encoded in a decoder with a memory with limited capacity, comprising: dividing the image into a plurality of regions, each of the regions indicating a different portion of the image and corresponding to a portion of variable length encoded data of multiple scan segments of the image file; in a first round, decoding variable length encoded data of at least some of the multiple scan segments of the image file for a first region of the regions to obtain a corresponding portion of the image while ignoring other regions; storing multiple position indicators of variable length encoded data of a second region of the regions for the multiple scan segments of the image file in the memory while decoding the first region; and in a second round, decoding variable length encoded data of at least some of the multiple scan segments of the image file for the second region by reference to the multiple position indicators instead of again decoding variable encoded data of the first region in the multiple scan segments of the image file; wherein the regions are decoded successively in multiple rounds including the first round and second round until all of the regions are decoded accordingly.