LZ77based

LZ77based refers to compression methods that are derived from or heavily inspired by the LZ77 algorithm, developed by Abraham Lempel and Jacob Ziv in 1977. In LZ77based schemes, data are represented using references to previously seen data within a sliding window. Each reference encodes how far back the match starts (the distance) and how long the match is (the length), often together with a literal symbol when no adequate match exists.

The encoding process typically searches for the longest match of the upcoming input in the current sliding window. If a sufficient match is found, a distance-length pair is emitted; otherwise, the next literal byte is emitted. The decoder mirrors the process, copying data from the previously reconstructed output according to the distance and length, thereby reconstructing the original stream without needing extra context.

LZ77based methods encompass a family of techniques and variants. LZSS is a well-known modification that improves efficiency by more explicitly separating literals from matches and by using fixed-size codes for both. The DEFLATE algorithm, widely used in formats such as gzip, PNG, and ZIP, combines LZ77-style length/distance matches with Huffman coding for symbol encoding, representing a practical, widely deployed implementation of LZ77based principles. Variants differ in parameters such as sliding window size, minimum match length, and the encoding scheme for matches and literals.

Applications of LZ77based compression include general file compression, data streams, and embedded systems where predictable decoding is advantageous. While effective for repetitive data, performance varies with data entropy and the chosen window and encoding parameters.