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@cgohlke cgohlke released this 12 Nov 01:52
v2026.11.11
172833c

Image transformation, compression, and decompression codecs

Imagecodecs is a Python library that provides block-oriented, in-memory buffer transformation, compression, and decompression functions for use in tifffile, liffile, czifile, zarr, and other scientific image input/output packages.

Decode and/or encode functions are implemented for Byte compressors: AEC, Blosc, Blosc2, Brotli, BZ2, CZI ZSTD1 and CHUNKED (with hilo filter), DEFLATE (zlib, isa-l, libdeflate, zlib-ng), GZIP, LZ4, LZ4F, LZ4H5, LZF, LZFSE, LZHAM, LZMA, LZO, LZW, OpenZL, PackBits, PGLZ (PostgreSQL LZ), Snappy, Szip, Zopfli, and ZStandard (ZSTD); Image formats: APNG, AVIF, BCn, BMP, DDS, EXR, GIF, HEIF, High-throughput JPEG 2000 (HTJ2K, JPH), JPEG (2 to 16-bit), JPEG 2000 (JP2, J2K), JPEG LS, JPEG XR, JPEG XS, Lossless JPEG (LJPEG, LJ92, JPEGLL), JPEGLI, MOZJPEG, PCX, PNG, QOI, RGBE (HDR), TGA (TARGA), TIFF, Ultra HDR (JPEG_R), WebP, and WIC (Windows Imaging Component); Image compressors: CCITT (RLE, T.4 and T.6), DICOM RLE, and PixarLog; Scientific compressors: B2ND, EER, HCOMP, Jetraw, LERC, NPZ, Pcodec, PLIO, RCOMP (Rice), SPERR, SZ3, and ZFP; Filters: Bitorder reversal, CMS (color space transformations), Delta, Quantize (Scale, BitGroom, BitRound, GranularBR), and XOR Delta; Shufflers: Bitshuffle, Byteshuffle, Floating Point Predictor, Meshopt, Packed Integers (TIFF, MONO p and packed), and WavPack, Type conversions: Bfloat16 (brain floating point), and Float24 (24-bit floating point); and Checksums: CRC-32, Adler-32, Fletcher-32, and Jenkins lookup3.

Changes

  • Rename JPEG8 codec to JPEG and deprecate JPEG8 alias (breaking).
  • Rename codec parameter of imread and imwrite to imagecodec (breaking).
  • Rename ultrahdr_encode_jpeg parameters and metadata keys (breaking).
  • Move Brunsli JPEG transcoding to brunsli_encode_jpeg/decode_jpeg (breaking).
  • Remove LJPEG fallback from jpeg_decode and jpeg_encode (breaking).
  • Remove Python bz2 module fallback from bz2_encode and bz2_decode.
  • Remove RGB565 color spaces from JPEG and MOZJPEG codecs (breaking).
  • Remove planar auto-detection in jpeg2k_encode and htj2k_encode (breaking).
  • Reject read-only output arrays in decoders (breaking).
  • Return 1D uint8 view or byte memoryview of user-provided out (breaking).
  • Reject bitspersample > 26 in jpeg2k_encode (breaking).
  • Reject invalid colorspace and subsampling in JPEG encoders (breaking).
  • Reject non-identity cICP matrix coefficients in PNG/APNG encoders (breaking).
  • Reject non-contiguous output arrays in cms_transform (breaking).
  • Reject unused whitepoint and primaries arguments in cms_profile (breaking).
  • Reject unknown codec names in register_codecs.
  • Reject object and zero itemsize dtypes in array codecs.
  • Change imread return_codec parameter to info (breaking).
  • Change integer out parameter to exact output size in all encoders (breaking).
  • Change mozjpeg_decode to alias of jpeg_decode (breaking).
  • Change jpegxl_encode/decode_jpeg options to keyword-only (breaking).
  • Change BLOSC2/B2ND parameters and enums to match python-blosc2 (breaking).
  • Change packints to pack 16, 32, and 64-bit integers big-endian (breaking).
  • Change webp_encode default to lossy if level is specified (breaking).
  • Change htj2k_encode resolutions to number of resolution levels (breaking).
  • Change ISAL.COMPRESSION.SPEED to level 0 (breaking).
  • Change numcodecs Jpegxl lossless default to None (breaking).
  • Change meshopt_encode default level to 2 and use vertex codec v1.
  • Change ultrahdr_encode default gainmap scale to library default.
  • Change b2nd_decode to disable threading.
  • Change BMP, PCX, and TGA codecs to thread-safe C libraries.
  • Change imread to try APNG for PNG and WIC for camera raw files.
  • Change AVIF creation times and cms_profile creation date to constant.
  • Derive jpeg2k_encode default colorspace from image layout (breaking).
  • Derive jpeg2k_encode color samples from colorspace parameter.
  • Derive JPEG default color space from CMYK and extended RGB input.
  • Convert CIELab to RGB in jpeg2k_decode (breaking).
  • Add JPEGLI codec based on jpegli library (Windows only).
  • Add iminfo function and info functions to many codecs.
  • Add imagecodecs.typing module with type aliases.
  • Add JpegCodec implementing the zarr-extensions jpeg spec.
  • Add more filters and codecs to BLOSC2/B2ND (#163).
  • Add jpeg_transcode and jpeg_merge functions (#160).
  • Add scale parameter to jpeg_decode (#159).
  • Add iccprofile parameter to JPEG, MOZJPEG, AVIF, and HEIF encoders.
  • Add hasalpha parameter to HEIF and JPEGXL encoders.
  • Add whitepoint and gamma parameters to jpegxl_encode.
  • Add primaries, transfer, whitepoint, and gamma parameters to jpegxl_decode.
  • Add planar parameter to jpegls_encode and jpegls_decode functions.
  • Add pixelformat parameter to jpegxr_decode.
  • Add extrasample parameter to jpeg2k_encode and write JP2 alpha channels.
  • Add option to create wavpack correction data.
  • Add hc parameter to lz4h5_encode.
  • Add byteorder parameter to PixarLog codecs.
  • Add displayp3, rec2020, sgray profiles and named curves to cms_profile.
  • Add new encoder parameters to numcodecs and zarr codecs.
  • Support typed contiguous output buffers in byte decompressors.
  • Support negative index in AVIF, HEIF, APNG, and EXR decoders (breaking).
  • Support non-native byte order input in most array codecs.
  • Support non-native byte order output in PCODEC, SPERR, and SZ3 decoders.
  • Support bytes-like ICC profiles in CMS functions.
  • Support short and prefixed codec names in register_codecs.
  • Support LERC blobs that use noData values (via lerc_decode_4D).
  • Support interrupting zopfli_encode.
  • Support zero delay and combined filters in APNG/PNG.
  • Support more DDS DX10 formats.
  • Support multi-member and padded GZIP streams and raw DEFLATE without size.
  • Support uniformly subsampled components in jpeg2k_decode.
  • Support 16-bit gray, 16-bit RGB, and gray-alpha images in spng_decode.
  • Support 15/16-bit colormaps and right-to-left images in tga_decode.
  • Support negative minexp, non-native byte order, and dtype strings in ZFP.
  • Improve parameter validation, error messages, and check functions.
  • Improve documentation.
  • Improve type hints.
  • Fix image layout of samples misinterpreted as frames.
  • Fix zarr/numcodecs codecs shape handling, serialization, and Cms metadata.
  • Fix photometric enum handling in HEIF, JPEGXL, APNG, and TIFF encoders.
  • Fix RGBE, ULTRAHDR, QUANTIZE, and TIFF colormap with non-native byte order.
  • Fix silent truncation and wrong checksums with data larger than 4 GB.
  • Fix silent data truncation in LZMA, LZ4F, LZ4H5, BZ2, SZIP, and AEC codecs.
  • Fix JPEGXR, JPEGXS, LJPEG encoders silently truncating output to small out.
  • Fix decoding concatenated streams in LZMA and BZ2 codecs.
  • Fix decoding highly compressible data in LZ4, Brotli, and AEC codecs.
  • Fix crashes, out-of-bounds access, and writes to read-only buffers in IMCD.
  • Fix aec_encode signedness of int8 and byte-order prefixed buffers.
  • Fix apng_decode alpha compositing and apng_encode delays > 65535 ms.
  • Fix (a)png_decode accepting truncated input or missing IEND chunk.
  • Fix interlace handling in png_decode and apng_decode.
  • Fix bitshuffle codecs ignoring itemsize of numpy arrays (breaking).
  • Fix bmp_decode of bitfields not 8 bits and segfaults with zero channel mask.
  • Fix CCITT decoders with 1D, ND, or buffer output.
  • Fix ccittfax4_decode infinite loop on crafted input (#158).
  • Fix cms_transform of gray volumes and big-endian floats, cms_info of v4.
  • Fix thread-safety of error logging in cms_transform and cms_profile_validate.
  • Fix decoding DDS cubemaps, texture arrays, and odd-sized textures.
  • Fix eer_decode dropping last code and with invalid parameters (#162).
  • Fix exr_encode default DWA and LJ2K compression levels.
  • Fix float24_encode rounding overflow and directed rounding of large values.
  • Fix gif_encode color resolution and gif_decode disposal and frame index.
  • Fix h5checksum functions ignoring value and racing CRC table (breaking).
  • Fix heif_decode of monochrome images.
  • Fix isal_decode ignoring checksum errors and isal_crc32c non-standard values.
  • Fix jpegsof3_decode OOB reads, uint8 wraparound, zero dimensions (#157).
  • Fix ljpeg_decode and jpegsof3_decode ignoring point transform.
  • Fix ljpeg_decode returning wrong samples with restart intervals.
  • Fix jpegxl_decode returning uninitialized frames with invalid index.
  • Fix jpegxs_decode hanging on truncated codestreams.
  • Fix jpegxs_encode silently corrupting data deeper than 14 bits (breaking).
  • Fix lzham_encode, lzfse_decode, and lzf_decode failing on specific data.
  • Fix lzw_decode output truncation beyond 4 GB.
  • Fix meshopt_decode ignoring shape and dtype if out is specified.
  • Fix quanttable and progressive parameters of mozjpeg_encode.
  • Fix packbits_encode quadratic runtime and silently truncated output.
  • Fix pcodec_encode failing with small pagesize.
  • Fix pglz_decode truncating output and reading past input (breaking).
  • Fix pixarlog_decode returning uninitialized rows and failing on long strips.
  • Fix plio_encode silently truncating floats.
  • Fix quantize_encode corrupting non-finite values and with too large nsd.
  • Fix rcomp_encode crash with nblock <= 0 and too small output estimate.
  • Fix rgbe_encode/decode output size and dtype, read-only out, invalid values.
  • Fix snappy_encode requiring level argument.
  • Fix sperr_decode of single-slice 3D data, short headers, and ignored dtype.
  • Fix sz3_decode heap overflow and uninitialized output with mismatched shape.
  • Fix tiff_encode writing non-deterministic gap bytes.
  • Fix tiff_decode silently accepting incomplete strip data.
  • Fix wavpack_encode of unsigned and non-native byte order data (breaking).
  • Fix webp_encode out-of-bounds reads with leading frame dimensions.
  • Fix WIC pixel formats, frame shapes, and conversion crashes (breaking).
  • Fix zfp_decode of data with full header when shape and dtype are specified.
  • Fix ZSTD1 and CHUNKED codecs with empty, truncated, or plain Zstd data.
  • Fix memory safety issues (buffer overflow, memory leaks, etc).
  • Fix many other issues.
Assets 26
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