Filkompression

Filkompression, or file compression, is the process of encoding information using fewer bits than the original representation to reduce storage requirements or transmission bandwidth. Compression can be either lossless, where the original data can be perfectly reconstructed, or lossy, where some information is discarded to achieve higher reduction. The choice depends on the data type and the acceptable trade-off between quality and size.

Lossless methods rely on statistical properties and redundancy in data. Common techniques include entropy coding such as Huffman or arithmetic coding, and dictionary-based schemes like LZ77 and LZW. Modern lossless formats combine these ideas, often with data transforms and block-wise processing, to achieve high compression while ensuring bit-for-bit recoverability.

Lossy compression intentionally discards information perceived as less important. It typically uses transform coding and quantization, guided by perceptual models. This approach is standard for images (JPEG, WebP), audio (MP3, AAC), and video (H.264/AVC, HEVC). Lossy codecs can achieve much higher compression ratios at the cost of some degradation in quality, which is measured by bitrate and perceptual quality metrics.

Compressed data is stored or transmitted in various formats. Archive formats such as ZIP, gzip, BZIP2, and 7z encapsulate compressed streams and may include metadata. Container formats for media, such as MP4 or MKV, combine compressed video and audio streams with metadata and subtitles. The choice of format affects compatibility, speed, and access to individual files within an archive.

Filkompression has played a central role in data storage, networking, and multimedia. It has evolved with standards like DEFLATE (a combination of LZ77 and Huffman coding) used in ZIP and gzip, and LZMA used by 7z. Ongoing research continues to optimize trade-offs among compression ratio, speed, and resource usage.