LZ77tyyppistä

LZ77tyyppistä refers to a family of data compression algorithms that are based on the principles of the LZ77 algorithm. The core idea of LZ77 and its derivatives is to replace repeated sequences of data with references to their previous occurrences. These references typically consist of a distance (how far back in the data the sequence was found) and a length (how long the matched sequence is).

This approach is a form of dictionary-based compression. Instead of explicitly storing the repeated string, the algorithm implicitly builds a dictionary of recently seen data. When a match is found, the algorithm outputs a literal character if it's a new byte, or an (offset, length) pair if it's a repeated sequence. This can significantly reduce the size of files, especially those with a lot of redundancy, such as text documents or certain types of images.

Numerous algorithms have been developed that build upon the LZ77 foundation. These variations often differ in how they manage the sliding window (the buffer of recent data to search for matches), how they choose the best match, and how they encode the (offset, length) pairs and literal characters. Examples of algorithms that are LZ77-type or share its core principles include DEFLATE (used in ZIP, Gzip, and PNG), LZO, and LZMA. The effectiveness of LZ77tyyppistä algorithms depends on the nature of the data being compressed and the specific implementation details of the algorithm.