Compression
CompressionType is used to express the desired compression type when encoding an image. Be aware that most image types only support a sub-set of the available compression types. If the compression type specified is incompatable with the image, ImageMagick selects a compression type compatable with the image type.
Entries
WebP compression.
Zstd compression (https://facebook.github.io/zstd/).
Lempel-Ziv compression (LZ77) as used in PKZIP and GNU gzip.
Run-Length encoded (RLE) compression
No compression
Lempel-Ziv-Welch (LZW) compression (caution, patented by Unisys)
JPEG compression
CCITT Group 4 FAX compression (used only for TIFF)
CCITT Group 3 FAX compression
BZip (Burrows-Wheeler block-sorting text compression algorithm and Huffman coding) as used by bzip2 utilities
Unset value.