FAST LOSSY INTERNET IMAGE TRANSMISSION APPARATUS AND METHODS

摘要

Fast lossy Internet image transmission ("FLIIT") systems and methods are provided for transmitting images (14), such as world wide web graphics, over the Internet. Forward error correction, added to an image during compression, enables the subsequent reconstruction of fragments lost during transmission by purposefully concentrating image bits within the portions of the image that have the greatest overall visual impact. Image fragments that are lost during transmission have little noticeable effect, and no time is spent on retransmitting lost fragments, such as in TCP/IP. FLIIT eliminates retransmission delays by strategically shielding important parts of subband coded images through forward error correction. Each subband is decomposed into a series of bitplanes ordered from the most significant to the least significant. An optimization procedure determines the subset of bitplanes to transmit as well as the number of bits to spend on forward error correction for each bitplane, recognizing that different bits in compressed images such as JPEG have different contributions to image fidelity. FLIIT also assesses current network conditions and adjusts transmission rates so as to accommodate network traffic: keeping the total transmission bits constant, more bits are adjusted to data during low network congestion, while more bits are adjusted to redundancy during high network congestion. A decoding section within a receiver unit, e.g., personal computer, decodes the transmitted image upon arrival across the Internet, providing a 2-4 factor improvement in speed over existing image transfers with the same quality.