Image compression and storage.

摘要

A sequence of image frames is compressed by dividing each frame into smaller blocks. Each block of all but the initial frame is compared with the corresponding block of the immediately previous frame, with only those blocks that are different being stored. A bit map 22 is used to store information about whether or not each block is different the corresponding block in the immediately preceding frame. To reconstruct a frame, this bit map is scanned for successive frames in reverse order, starting from the bits corresponding to the object frame to be reconstructed to determine in which frame each block last changed. The logical storage page of each block of the image data is then obtained by identifying the frame when that block last changed. Any frame can therefore be quickly reconstructed by accessing only those pages actually used to store block data of the frame to be reconstructed.