DEFLATEAlgorithmus

The Deflate algorithm, sometimes referred to as DeflateAlgorithmus, is a lossless data compression method that combines LZ77 compression with Huffman coding. It was designed by Phil Katz for PKWARE and became widely used with PKZIP. The format was standardized as Deflate in RFC 1951 and is used in various container formats and protocols, including gzip, zlib, PNG, and many ZIP-based archives. It balances compression ratio, speed, and portability.

How it works: Data to be compressed is processed in blocks. Each block can be stored uncompressed, compressed with fixed Huffman codes, or compressed with dynamic Huffman codes. Within a compressed block, the input is scanned to replace repeated sequences with length/distance pairs drawn from a 32-kilobyte sliding window. The encoder builds two Huffman trees: one for literals and length codes, and another for distance codes. When dynamic trees are used, the three trees (two for data and one for code lengths) are themselves compressed using a small code-length Huffman tree. The resulting bit stream is written least-significant-bit first.

Performance and usage: Deflate provides strong compression for a wide range of data while keeping decompression fast. It remains the de facto standard in many software stacks, including web servers, archives, and image formats. The approach is compactly implementable and widely supported by libraries across languages. Limitations include diminished effectiveness on data that is already compressed and varying memory requirements due to the sliding window and multiple Huffman trees.

History and variants: Deflate traces back to work in the 1990s by Phil Katz and is maintained as a widely implemented standard. There are several variants and related formats (such as zlib and gzip wrappers) that tailor the raw Deflate stream to different framing or metadata needs, but the core compression method remains consistent across implementations.