Lossless
A compression method that preserves original data perfectly upon decompression. No quality degradation occurs, but file size reduction is less than lossy compression.
Lossless compression allows perfect reconstruction of original data without any loss. Since image quality remains completely intact, it is ideal for archival storage and intermediate editing files.
Key algorithms include Deflate (used in PNG), LZW (used in GIF and TIFF), and Huffman coding. These exploit repetitive patterns and statistical biases in data, achieving higher ratios on images with large flat-color areas. Complex photographs compress poorly, resulting in large files.
Compared to lossy compression, lossless files are typically 2-10x larger at equivalent quality. Web delivery favors lossy JPEG or WebP for photos, reserving lossless PNG for logos and screenshots requiring precision. The image conversion tool applies lossless compression when converting to PNG.