Image transmission system with line averaging preview mode using two-pass block-edge interpolation

摘要

A preview still video image, comprising a smaller number of binary bits to expedite digital transmission, is constructed block-by-block from a full-quality still video image by (a) sampling every n video pixels in each horizontal video line of each block and averaging between adjacent ones of the sampled pixels, and (b) sampling every m horizontal video lines in each block and averaging between adjacent ones of the sampled lines. An image is reconstructed from the preview image by using a buffer which temporarily stores the last video line in each block, and interpolating it with the first line in the next block, as well as interpolating all subsequent adjacent line pairs in the block. Adjacent pairs of the sampled pixels in each line are also interpolated. The image thus reconstructed comprises as many pixels and horizontal lines as the full-quality image.