image

Features:

• Added GenericImage::copy_from_samples that can be implemented for images
  that can be efficiently filled from a matrix-layout of samples. Its default
  implementation will not defer to copy_from, consider implementing this if
  you specialized the latter.
• Added GenericImageView::to_pixel_view that can be implemented to describe
  the buffer in terms our FlatSamples matrix layout, if applicable. This
  allows algorithms over generic images to run a specialized version where they
  can be more efficient over an raw input slice.
• Added ImageBuffer::from_raw_bgr{,a} to efficiently byte-swap images into
  the RGBA layout of the buffer (#2596).
• Added ExtendedColorType::Rgb5x1 to represent 5-bit colors as from TGA (#2609).
• Added metadata::LoopCount and AnimationDecoder::loop_count to query if
  animations should repeat in a uniform manner (gif, webp, avif) (#2719, #2786).
• load_from_memory now utilizes format detection hooks if any are applicable.

Structural changes:

• Various changes that reduce the compile time of image on codegen by
  reducing the number of monomorphizations (#2804, #2800, #2807).
• GenericImage::copy_from's default implementation tries copy_from_samples
  first if the source can be successfully cast with to_pixel_view.
• <ImageBuffer as GenericImage>::copy_from is now must faster for
  ImageBuffer when the source implements GenericImageView::to_pixel_view.
• <SubImage<_> as GenericImage>::copy_from inherits the previously mentioned
  optimizations for pixel sources when the inner type provides them. It also
  provides to_pixel_view based on the inner type.
• ImageBuffer::as_flat_samples no longer requires AsRef<[P::Subpixel]> for
  the underlying container, just Deref (#2777).

Bug fixes:

• Fixed a panic in TGA where indices have more bits than mapped colors (#2673).

Notable decoder changes:

• Bump tiff to 0.11, supporting planar layout images (#2743).
• ICC profiles can now be written for TIFF files (#2746)
• Update ravif to 0.13, supporting EXIF (#2733).
• Update jpeg-encoder to 0.7 bringing SIMD acceleration (#2736).
• The pnm decoder decodes binary data quicker with fewer allocations (#2797).
• The tga decoder handles 5-bit data and colormaps correctly (#2608, #2609).

Compatibility notes (new section):

• Bump rust-version to 1.88.
• Registered hooks now normalize the file extension they are registered against
  to ascii-lowercase. It is no longer necessary to register all such variants.
  This may conflate two hooks that previously hooked the same format with
  different casing.

Features:

• Support extracting XMP metadata from PNG, JPEG, GIF, WebP and TIFF files (#2567, #2634, #2644)
• Support reading IPTC metadata from PNG and JPG files (#2611)
• Support reading ICC profile from GIF files (#2644)
• Allow setting a specific DEFLATE compression level when writing PNG (#2583)
• Initial support for 16-bit CMYK TIFF files (#2588)
• Allow extracting the alpha channel of a Pixel in a generic way (#2638)

Structural changes:

• EXR format decoding now only uses multi-threading via Rayon when the rayon feature is enabled (#2643)
• Upgraded zune-jpeg to 0.5.x, ravif to 0.12.x, gif to 0.14.x
• pnm: parse integers in PBM/PGM/PPM headers without allocations (#2620)
• Replace doc_auto_cfg with doc_cfg (#2637)

Bug fixes:

• Do not encode empty JPEG images (#2624)
• tga: reject empty images (#2614)
• tga: fix orientation flip for color mapped images (#2607)
• tga: adjust colormap lookup to match tga 2.0 spec (#2608)

Features:

• Support extracting XMP metadata from PNG, JPEG, GIF, WebP and TIFF files (#2567, #2634, #2644)
• Support reading IPTC metadata from PNG and JPG files (#2611)
• Support reading ICC profile from GIF files (#2644)
• Allow setting a specific DEFLATE compression level when writing PNG (#2583)
• Initial support for 16-bit CMYK TIFF files (#2588)
• Allow extracting the alpha channel of a Pixel in a generic way (#2638)

Structural changes:

• EXR format decoding now only uses multi-threading via Rayon when the rayon feature is enabled (#2643)
• Upgraded zune-jpeg to 0.5.x, ravif to 0.12.x, gif to 0.14.x
• pnm: parse integers in PBM/PGM/PPM headers without allocations (#2620)
• Replace doc_auto_cfg with doc_cfg (#2637)

Bug fixes:

• Do not encode empty JPEG images (#2624)
• tga: reject empty images (#2614)
• tga: fix orientation flip for color mapped images (#2607)
• tga: adjust colormap lookup to match tga 2.0 spec (#2608)

Re-release of 0.25.7

Fixes:

• Reverted a signature change to load_from_memory that lead to large scale
  type inference breakage despite being technically compatible.
• Color conversion Luma to Rgb used incorrect coefficients instead of broadcasting.

From version 0.25.7 (yanked)

Features:

• Added an API for external image format implementations to register themselves as decoders for a specific format in image (#2372)
• Added CICP awarenes via moxcms to support color spaces (#2531). The support for transforming is limited for now and will be gradually expanded.
• You can now embed Exif metadata when writing JPEG, PNG and WebP images (#2537, #2539)
• Added functions to extract orientation from Exif metadata and optionally clear it in the Exif chunk (#2484)
• Serde support for more types (#2445)
• PNM encoder now supports writing 16-bit images (#2431)

API improvements:

• save, save_with_format, write_to and write_with_encoder methods on DynamicImage now automatically convert the pixel format when necessary instead of returning an error (#2501)
• Added DynamicImage::has_alpha() convenience method
• Implemented TryFrom<ExtendedColorType> for ColorType (#2444)
• Added const HAS_ALPHA to trait Pixel
• Unified the error for unsupported encoder colors (#2543)
• Added a hooks module to customize builtin behavior, register_format_detection_hook and register_decoding_hook for the determining format of a file and selecting an ImageDecoder implementation respectively. (#2372)

Performance improvements:

• Gaussian blur (#2496) and box blur (#2515) are now faster
• Improve compilation times by avoiding unnecessary instantiation of generic functions (#2468, #2470)

Bug fixes:

• Many improvements to image format decoding: TIFF, WebP, AVIF, PNG, GIF, BMP, TGA
• Fixed GifEncoder::encode() ignoring the speed parameter and always using the slowest speed (#2504)
• .pnm is now recognized as a file extension for the PNM format (#2559)

Re-release of 0.25.7

Fixes:

• Reverted a signature change to load_from_memory that lead to large scale type inference breakage despite being technically compatible.
• Color conversion Luma to Rgb used incorrect coefficients instead of broadcasting.

Features:

• Added an API for external image format implementations to register themselves as decoders for a specific format in image (#2372)
• Added CICP awarenes via moxcms to support color spaces (#2531). The support for transforming is limited for now and will be gradually expanded.
• You can now embed Exif metadata when writing JPEG, PNG and WebP images (#2537, #2539)
• Added functions to extract orientation from Exif metadata and optionally clear it in the Exif chunk (#2484)
• Serde support for more types (#2445)
• PNM encoder now supports writing 16-bit images (#2431)

API improvements:

• save, save_with_format, write_to and write_with_encoder methods on DynamicImage now automatically convert the pixel format when necessary instead of returning an error (#2501)
• Added DynamicImage::has_alpha() convenience method
• Implemented TryFrom<ExtendedColorType> for ColorType (#2444)
• Added const HAS_ALPHA to trait Pixel
• Unified the error for unsupported encoder colors (#2543)
• Added a hooks module to customize builtin behavior, register_format_detection_hook and register_decoding_hook for the determining format of a file and selecting an ImageDecoder implementation respectively. (#2372)

Performance improvements:

• Gaussian blur (#2496) and box blur (#2515) are now faster
• Improve compilation times by avoiding unnecessary instantiation of generic functions (#2468, #2470)

Bug fixes:

• Many improvements to image format decoding: TIFF, WebP, AVIF, PNG, GIF, BMP, TGA
• Fixed GifEncoder::encode() ignoring the speed parameter and always using the slowest speed (#2504)
• .pnm is now recognized as a file extension for the PNM format (#2559)

Features:

• Added an API for external image format implementations to register themselves as decoders for a specific format in image (#2372)
• Added CICP awarenes via moxcms to support color spaces (#2531). The support for transforming is limited for now and will be gradually expanded.
• You can now embed Exif metadata when writing JPEG, PNG and WebP images (#2537, #2539)
• Added functions to extract orientation from Exif metadata and optionally clear it in the Exif chunk (#2484)
• Serde support for more types (#2445)
• PNM encoder now supports writing 16-bit images (#2431)

Structural changes:

• Increased MSRV to 1.85.0 (from 1.78.0)

API improvements:

• save, save_with_format, write_to and write_with_encoder methods on DynamicImage now automatically convert the pixel format when necessary instead of returning an error (#2501)
• Added DynamicImage::has_alpha() convenience method
• Implemented TryFrom<ExtendedColorType> for ColorType (#2444)
• Added const HAS_ALPHA to trait Pixel
• Unified the error for unsupported encoder colors (#2543)
• Added a hooks module to customize builtin behavior, register_format_detection_hook and register_decoding_hook for the determining format of a file and selecting an ImageDecoder implementation respectively. (#2372)

Performance improvements:

• Gaussian blur (#2496) and box blur (#2515) are now faster
• Improve compilation times by avoiding unnecessary instantiation of generic functions (#2468, #2470)

Bug fixes:

• Many improvements to image format decoding: TIFF, WebP, AVIF, PNG, GIF, BMP, TGA
• Fixed GifEncoder::encode() ignoring the speed parameter and always using the slowest speed (#2504)
• .pnm is now recognized as a file extension for the PNM format (#2559)

Release 0.25.6 (#2441)

Features:

• Improved format detection (#2418)
• Implement writing ICC profiles for JPEG and PNG images (#2389)

Bug fixes:

• JPEG encoding bugfix (#2387)
• Expanded ICO format detection (#2434)
• Fixed EXR bug with NaNs (#2381)
• Various documentation improvements

Features:

• Added support for decoding 10-bit and 12-bit AVIF
• Initial, opt-in serde support for an enum. This may be extended to other types in the future.

Bug fixes:

• Multiple bug fixes in AVIF decoding
• The rayon feature now correctly toggles the use of rayon when encoding AVIF. (Previously it would be either always on or always off depending on the version of the ravif crate in your dependency tree.)
• "jfif" file extension for JPEG images is now recognized

Features:

• Added support for decoding 10-bit and 12-bit AVIF
• Initial, opt-in serde support for an enum. This may be extended to other types in the future.

Bug fixes:

• Multiple bug fixes in AVIF decoding
• The rayon feature now correctly toggles the use of rayon when encoding AVIF. (Previously it would be either always on or always off depending on the version of the ravif crate in your dependency tree.)
• "jfif" file extension for JPEG images is now recognized

Propose wording for republishing as 0.25.4

Features:

• Much faster decoding of lossless WebP due to a variety of optimizations. Our benchmarks show 2x to 2.5x improvement.
• Added support for orientation metadata, so that e.g. smartphone camera images could be displayed correctly:
  • Added ImageDecoder::orientation() and implemented orientation metadata extraction for JPEG, WebP and TIFF formats
  • Added DynamicImage::apply_orientation() to apply the orientation to an image
• Added support for extracting Exif metadata from images via ImageDecoder::exif_metadata(), and implemented it for JPEG and WebP formats
• Added ImageEncoder::set_icc_profile() and implemented it for WebP format. Pull requests with implementations for other formats are welcome.
• Added DynamicImage::fast_blur() for a linear-time approximation of Gaussian blur, which is much faster at larger blur radii

Bug fixes:

• Fixed some APNG images being decoded incorrectly
• Fixed the iterator over animated WebP frames to return None instead of an error when the end of the animation is reached

Features:

• Much faster decoding of lossless WebP due to a variety of optimizations. Our benchmarks show 2x to 2.5x improvement.
• Added support for orientation metadata, so that e.g. smartphone camera images could be displayed correctly:
  • Added ImageDecoder::orientation() and implemented orientation metadata extraction for JPEG, WebP and TIFF formats
  • Added DynamicImage::apply_orientation() to apply the orientation to an image
• Added support for extracting Exif metadata from images via ImageDecoder::exif_metadata(), and implemented it for JPEG and WebP formats
• Added ImageEncoder::set_icc_profile() and implemented it for WebP format. Pull requests with implementations for other formats are welcome.
• Added DynamicImage::fast_blur() for a linear-time approximation of Gaussian blur, which is much faster at larger blur radii

Bug fixes:

• Fixed some APNG images being decoded incorrectly
• Fixed the iterator over animated WebP frames to return None instead of an error when the end of the animation is reached
• Toggling the rayon feature now correctly toggles the use of rayon within ravif (AVIF encoder). Previously it would be either always on or always off, depending on the ravif version.

Yanked! This version accidentally missed a commit that should have been included with the release. The Orientation struct should be in the appropriate module instead of the top-level. This release won't be supported.

Features:

• Added the HDR encoder to supported formats in generic write methods with the
  hdr feature enabled. Supports 32-bit float RGB color only, for now.
• When cloning ImageBuffer, DynamicImage and Frame the existing buffer
  will now be reused if possible.
• Added image::ImageReader as an alias.
• Implement ImageEncoder for HdrEncoder.

Structural changes

• Switch from byteorder to byteorder-lite, consolidating some casting
  unsafety to bytemuck.
• Many methods on DynamicImage and buffers gained #[must_use] indications.

Bug fixes:

• Removed test data included in the crate archive.
• The WebP animation decoder stops when reaching the indicate frame count.
• Fixed bugs in the bmp decoder.
• Format support gated on the exr feature now compiles in isolation.

Features:

• Added the HDR encoder to supported formats in generic write methods with the hdr feature enabled. Supports 32-bit float RGB color only, for now.
• When cloning ImageBuffer, DynamicImage and Frame the existing buffer will now be reused if possible.
• Added image::ImageReader as an alias.
• Implement ImageEncoder for HdrEncoder.

Structural changes

• Switch from byteorder to byteorder-lite, consolidating some casting unsafety to bytemuck.
• Many methods on DynamicImage and buffers gained #[must_use] indications.

Bug fixes:

• Removed test data included in the crate archive.
• The WebP animation decoder stops when reaching the indicate frame count.
• Fixed bugs in the bmp decoder.
• Format support gated on the exr feature now compiles in isolation.

Release 0.25.1 (#2187)

Bug fixes:

• Fixed corrupt JPEG output when attempting to encode images containing an alpha channel.
• Only accept ".ff" file extension for farbfeld images.
• Correct farbfeld feature flag for ImageFormat::{reading_enabled, writing_enabled}.
• Disable strict mode for JPEG decoder.
• Add nasm feature to optionally enable faster AVIF encoding.

Breaking changes:

• Added BufRead + Seek bound on many decoders.
• Use ExtendedColorType instead of ColorType when encoding.
• Removed ImageOutputFormat, GenericImageView::bounds, and several other deprecated items.
• Removed incremental decoding support and changed ImageDecoder so the trait is object safe.
• Pixel types are now repr(transparent) rather than repr(C).
• Made color_quant dependency optional.
• Renamed some feature flags.

Structural changes:

• Increased MSRV to 1.67.1

Codec changes:

• Switched to image-webp for WebP encoding.
• Switched to zune-jpeg for JPEG decoding.
• Made the HDR decoder produce f32 images.
• Removed DXT encoding and decoding support.

Structural changes:

• Relicense to MIT OR Apache-2.0
• Increase MSRV 1.63.0

New features:

• Support limits in PNG animation decoding.
• Added offsets to SubImage to compensate for the now-deprecated bounds call from GenericImageView.

Bug fixes:

• Correct limit tests for TIFF.
• Avoid overflow in gif::Decoder::buffer_size.
• Return error instead of using assertions for Avif decoder unsupported or invalid bit depth.

New features:

• Added pure-Rust lossless WebP encoding.
• Added DynamicImage::new method.
• Added PngDecoder::gamma_value method.
• Added ImageFormat::{reading_enabled, writing_enabled, all}.
• TGA encoder now supports RLE encoding.
• Add rayon parallel iterators behind an optional rayon feature.
• Support CMYK TIFF images.
• Implement From<DynamicImage> for all image types.

Bug fixes:

• Fix decoding pngs with invalid text chunks.
• Handle non-fatal error dav1d::Error::Again.
• Do not round floats in interpolate.
• PNM decoder now scales samples according to specified maximum.
• Fix wrong implementation of unsharpen filter.
• Fix GifDecoder::with_limits to raise an error when limits are exceeded.

New features:

• Added {ImageBuffer, DynamicImage}::write_with_encoder to simplify writing images with custom settings.
• Expose ICC profiles stored in tiff and webp files.
• Added option to set the background color of animated webp images.
• New methods for sampling and interpolation of GenericImageViews

Bug fixes:

• Fix panic on empty dxt.
• Fix several panics in webp decoder.
• Allow unknown chunks at the end of webp files.

• Add support for QOI.
• ImageDecoders now expose ICC profiles on supported formats.
• Add support for BMPs without a file header.
• Improved AVIF encoder.
• WebP decoding fixes.

Structural changes:

• Increased the minimum supported Rust version (MSRV) to 1.61.
• Increased the version requirement for the tiff crate to 0.8.0.
• Increased the version requirement for the jpeg crate to 0.3.0.

Bug fixes:

• The as_rgb32f function of DynamicImage is now correctly documented.
• Fixed a crash when decoding ICO images. Added a regression test.
• Fixed a panic when transforming webp images. Added a regression test.
• Added a check to prevent integer overflow when calculating file size for BMP images. The missing check could panic in debug mode or else set an incorrect file size in release mode.
• Upgraded the PNG image encoder to use the newer PngEncoder::write_image instead of the deprecated PngEncoder::encode which did not account for byte order and could result in images with incorrect colors.
• Fixed InsufficientMemory error when trying to decode a PNG image.
• Fix warnings and CI issues.
• Typos and links in the documentation have been corrected.

Performance:

• Added check for dynamic image dimensions before resizing. This improves performance in cases where the image does not need to be resized or has already been resized.

New Features:

• Encoding for webp is now available with the native library. This needs to be activate explicitly with the web-encoder feature.
• exr decoding has gained basic limit support.

Bug fixes:

• The Iterator::size_hint implementation of pixel iterators has been fixed to return the current length indicated by its ExactSizeIterator hint.
• Typos and bad references in the documentation have been removed.

Performance:

• ImageBuffer::get_pixel{,_mut} is now marked inline.
• resize now short-circuits when image dimensions are unchanged.

New Features:

• TiffDecoder now supports setting resource limits.

Bug fixes:

• Fix compile issues on little endian systems.
• Various panics discovered by fuzzing.

Structural changes:

• CI now runs cargo-deny, checking dependent crates to an OSS license list and against RUSTSEC advisories.

New Features:

• The WebP decoder recognizes and decodes images with VP8X header.
• The DDS decoder recognizes and decodes images with DX10 headers.

Bug fixes:

• Calling DynamicImage/ImageBuffer's methods write_to and save will now work properly even if the backing container is larger than the image layout requires. Only the relevant slice of pixel data is passed to the encoder.
• Fixed a OOM-panic caused by malformed images in the gif decoder.

Bug Fixes:

• ImageBuffer::get_pixel_checked would sometimes return the incorrect pixel.
• PNG encoding would sometimes not recognize unsupported color.

Breaking changes

Structural changes:

• Minimum Rust version is now 1.56 and may change in minor versions until further notice. It is now tracked in the library's Cargo.toml, instead, by the standard [package.rust-version] field. Note: this applies to the library itself. You may need different version resolutions for dependencies when using a non-stable version of Rust.
• The math::utils::{nq, utils} modules have been removed. These are better served through the color_quant crate and the standard library respectively.
• All codecs are now available through image::codecs, no longer top-level.
• ExtendedColorType and DynamicImage have been made #[non_exhaustive], providing more methods instead of exhaustive matching.
• Reading images through the generic io::Reader, as well as generic convenience interfaces, now requires the underlying reader to be BufRead + Seek. This allows more efficient support more formats. Similarly, writing now requires writers to be Write + Seek.
• The Bgra* variants of buffers, which were only half-supported, have been removed. The owning buffer types ImageBuffer and DynamicImage fundamentally already make a choice in supported pixel representations. This allows for more consistent internal behavior. Callers are expected to convert formats when using those buffers, which they are required to do in any case already, and which is routinely performed by decoders.

Trait reworks:

• The Pixel trait is no longer implemented quite as liberally for structs defined in the crate. Instead, it is now restricted to a set of known channel which ensures accuracy in computations involving those channels.
• The ImageDecoderExt trait has been renamed to ImageDecoderRect, according to its actual functionality.
• The Pixel trait and its Subpixel field no longer require (or provide) a 'static lifetime bound.
• The Pixel trait no longer requires specifying an associated, constant ColorType. This was of little relevance to computation but made it much harder to implement and extend correctly. Instead, the private PixelWithColorType extension is added for interfaces that require a properly known variant.
• Reworked how SubImage interacts with the GenericImage trait. It is now a default implementation. Note that SubImage now has inherent methods that avoid double-indirection, the trait's method will no longer avoid this.
• The Primitive trait now requires implementations to provide a minimum and maximum logical bound for the purpose of converting to other primitive representations.

Additions

Image formats:

• Reading lossless WebP is now supported.
• The OpenEXR format is now supported.
• The jpeg decoder has been upgraded to Lossless JPEG.
• The AvifEncoder now correctly handles alpha-less images. Some additional color formats are converted to RGBA as well.
• The Bmp codec now decodes more valid images. It can decode a raw image without performing the palette mapping. It provides a method to access the palette. The encoder provides the inverse capabilities.
• Tiff is now an output format.

Buffers and Operations:

• The channel / primitive type f32 is now supported. Currently only the OpenEXR codec makes full use of it but this is expected to change.
• ImageBuffer::{get_pixel_checked, get_pixel_mut_checked} provide panic-free access to pixels and channels by returning Option<&P> and Option<&mut P>.
• ImageBuffer::write_to has been added, encoding the buffer to a writer. This method already existed on DynamicImage.
• DynamicImage now implements From<_> for all supported buffer types.
• DynamicImage now implements Default, an empty Rgba8 image.
• imageops::overlay now takes coordinates as i64.

Limits:

• Added Limits and LimitSupport, utilized in io::Reader. These can be configured for rudimentary protection against resource exhaustion (images pretending to require a very large buffer). These types are not yet exhaustive by design, and more and stricter limits may be added in the future.
• Encoders that do provide inherent support for limits, or reserve a significant amount of internal memory, are urged to implement the set_limits extension to ImageDecoder. Some strict limit are opt-in, which may cause decoding to fail if not supported.

Miscellaneous:

• PNMSubtype has been renamed to PnmSubtype, by Rust's naming scheme.
• Several incorrectly capitalized PNM* aliases have been removed.
• Several enum types that had previously used a hidden variant now use the official #[non_exhaustive] attribute instead.

• Unified gif blending in different decode methods, fixing out-of-bounds checks in a number of weirdly positioned frames.

• Hardened TGA decoder against a number of malicious inputs.

• Fix forward incompatible usage of the panic macro.

• Fix load_rect for gif reaching unreachable!() code.

• Added ExtendedColorType::A8.

• Allow TGA to load alpha-only images.

• Optimized load_rect to avoid unnecessary seeks.

• Fix an inconsistency in supported formats of different methods for encoding an image.

• Fix thumbnail choosing an empty image. It now always prefer non-empty image dimensions.

• Fix integer overflow in calculating requires bytes for decoded image buffers for farbfeld, hdr, and pnm decoders. These will now error early.

• Fix a panic decoding certain jpeg image without frames or meta data.

• Optimized the jpeg encoder.

• Optimized GenericImage::copy_from default impl in various cases.

• Add avif decoders. You must enable it explicitly and it is not covered by our usual MSRV policy of Rust 1.34. Instead, only latest stable is supported.

• Add ImageFormat::{can_read, can_write}

• Add Frame::buffer_mut

• Add speed and quality options on avif encoder.

• Add speed parameter to gif encoder.

• Expose control over sequence repeat to the gif encoder.

• Add {contrast,brighten,huerotate}_in_place functions in imageproc.

• Relax Default impl of ImageBuffer, removing the bound on the color type.

• Derive Debug, Hash, PartialEq, Eq for DynamicImage

• Fix a soundness issue affecting the impls of Pixel::from_slice_mut. This would previously reborrow the mutable input reference as a shared one but then proceed to construct the mutable result reference from it. While UB according to Rust's memory model, we're fairly certain that no miscompilation can happen with the LLVM codegen in practice. See 5cbe1e6767d11aff3f14c7ad69a06b04e8d583c7 for more details.

• Fix imageops::blur panicking when sigma = 0.0. It now defaults to 1.0 as all negative values.

• Fix re-exporting png::{CompressionType, FilterType} to maintain SemVer compatibility with the 0.23 releases.

• Add ImageFormat::from_extension

• Add copyless DynamicImage to byte slice/vec conversion.

• Add bit-depth specific into_ and to_ DynamicImage conversion methods.

• The NeuQuant implementation is now supplied by color_quant. Use of the type defined by this library is discouraged.
• The jpeg decoder can now downscale images that are decoded by 1,2,4,8.
• Optimized the jpeg encoding ~5-15%.
• Deprecated the clamp function. Use num-traits instead.
• The ICO decoder now accepts an empty mask.
• Fixed an overflow in ICO mask decoding potentially leading to panic.
• Added ImageOutputFormat for AVIF
• Updated tiff to 0.6 with lzw performance improvements.

• Added AVIF encoding capabilities using the ravif crate. Please note that the feature targets the latest stable compiler and is not enabled by default.
• Added ImageBuffer::as_raw to inspect the underlying container.
• Updated gif to 0.11 with large performance improvements.

• Introduced correctly capitalized aliases for some scream case types
• Introduced imageops::{vertical_gradient, horizontal_gradient} for writing simple color gradients into an image.
• Sped up methods iterating over Pixels, PixelsMut, etc. by using exact chunks internally. This should auto-vectorize ImageBuffer::from_pixel.
• Adjusted Clone impls of iterators to not require a bound on the pixel.
• Add Debug impls for iterators where the pixel's channel implements it.
• Add comparison impls for FilterType

• flat::Error now implements the standard Error trait
• The type parameter of Map has been relaxed to ?Sized
• Added the imageops::tile function that repeats one image across another

• Iterators over immutable pixels of ImageBuffer can now be cloned
• Added a tga encoder
• Added ColorMap::lookup, an optional reversal of the map
• The EncodableLayout trait is now exported

• Added png::ApngDecoder, an adapter decoding the animation in an APNG.
• Fixed a bug in jpeg encoding that would darken output colors.
• Added a utility constructor FlatSamples::with_monocolor.
• Added ImageBuffer::as_flat_samples_mut which is a mutable variant of the existing ffi-helper ImageBuffer::as_flat_samples.

• The png encoder now allows configuring compression and filter type. The output is not part of stability guarantees, see its documentation.
• The jpeg encoder now accepts any implementor of GenericImageView. This allows images that are only partially present in memory to be encoded.
• ImageBuffer now derives Hash, PartialEq, Eq.
• The Pixels/PixelsMut iterator no longer yields out-of-bounds pixels when the underlying buffer is larger than required.
• The pbm decoder correctly decodes ascii data again, fixing a regression where it would use the sample value 1 as white instead of 255.
• Fix encoding of RGBA data in gif frames.
• Constructing a Rows/RowsMut iterator no longer panics when the image has a width or height of 0.

• Improved the performance of decoding animated gifs
• Added crop_imm which functions like crop but on a shared reference
• The gif DisposalMethod::Any is treated as Keep, consistent with browsers
• Most errors no longer allocate a string, instead implement Display.
• Add some implementations of Error::source

• Added ColorType::has_alpha to facilitate lossless conversion
• Recognize extended WebP formats for decoding
• Added decoding and encoding for the farbfeld format
• Export named iterator types created from various ImageBuffer methods
• Error in jpeg encoder for images larger than 65536 pixels, fixes panic

• The dependency on jpeg-decoder now reflects minimum requirements.

• Fix cmyk_to_rgb (jpeg) causing off by one rounding errors.
• A number of performance improvements for jpeg (encode and decode), bmp, vp8
• Added more details to errors for many formats

This major release intends to improve the interface with regards to handling of color format data and errors for both decoding and encoding. This necessitated many breaking changes anyways so it was used to improve the compliance to the interface guidelines such as outstanding renaming.

It is not yet perfect with regards to color spaces but it was designed mainly as an improvement over the current interface with regards to in-memory color formats, first. We'll get to color spaces in a later major version.

• Heavily reworked ColorType:
  • This type is now used for denoting formats for which we support operations on buffers in these memory representations. Particularly, all channels in pixel types are assumed to be an integer number of bytes (In terms of the Rust type system, these are Sized and one can crate slices of channel values).
  • An ExtendedColorType is used to express more generic color formats for which the library has limited support but can be converted/scaled/mapped into a ColorType buffer. This operation might be fallible but, for example, includes sources with 1/2/4-bit components.
  • Both types are non-exhaustive to add more formats in a minor release.
  • A work-in-progress (#1085) will further separate the color model from the specific channel instantiation, e.g. both 8-bit RGB and 16-bit BGR are instantiations of RGB color model.
• Heavily rework ImageError:
  • The top-level enum type now serves to differentiate cause with multiple opaque representations for the actual error. These are no longer simple Strings but contains useful types. Third-party decoders that have no variant in ImageFormat have also been considered.
  • Support for Error::source that can be downcast to an error from a matching version of the underlying decoders. Note that the version is not part of the stable interface guarantees, this should not be relied upon for correctness and only be used as an optimization.
  • Added image format indications to errors.
  • The error values produced by decoder will be upgraded incrementally. See something that still produces plain old String messages? Feel free to send a PR.
• Reworked the ImageDecoder trait:
  • read_image takes an output buffer argument instead of allocating all memory on its own.
  • The return type of dimensions now aligns with GenericImage sizes.
  • The colortype method was renamed to color_type for conformity.
• The enums ColorType, DynamicImage, imageops::FilterType, ImageFormat no longer re-export all of their variants in the top-level of the crate. This removes the growing pollution in the documentation and usage. You can still insert the equivalent statement on your own: use image::ImageFormat::{self, *};
• The result of encode operations is now uniformly an ImageResult<()>.
• Removed public converters from some tiff, png, gif, jpeg types, mainly such as error conversion. This allows upgrading the dependency across major versions without a major release in image itself.
• On that note, the public interface of gif encoder no longer takes a gif::Frame but rather deals with image::Frame only. If you require to specify the disposal method, transparency, etc. then you may want to wait with upgrading but (see next change).
• The gif encoder now errors on invalid dimensions or unsupported color formats. It would previously silently reinterpret bytes as RGB/RGBA.
• The capitalization of ImageFormat and other enum variants has been adjusted to adhere to the API guidelines. These variants are now spelled Gif, Png, etc. The same change has been made to the name of types such as HDRDecoder.
• The Progress type has finally received public accessor method. Strange that no one reported them missing.
• Introduced PixelDensity and PixelDensityUnit to store DPI information in formats that support encoding this form of meta data (e.g. in jpeg).

• Added GenericImage::copy_within, specialized for ImageBuffer
• Fixed decoding of interlaced gif files
• Prepare for future compatibility of array IntoIterator in example code

• Added in-place variants for flip and rotate operations.
• The bmp encoder now checks if dimensions are valid for the format. It would previously write a subset or panic.
• Removed deprecated implementations of Error::description
• Added DynamicImage::into_* which convert without an additional allocation.
• The PNG encoder errors on unsupported color types where it had previously silently swapped color channels.
• Enabled saving images as gif with save_buffer.

• Added a new module io containing a configurable Reader. It can replace the bunch of free functions: image::{load_*, open, image_dimensions} while enabling new combinations such as open but with format deduced from content instead of file path.
• Fixed const_err lint in the macro expanded implementations of Pixel. This can only affect your crate if image is used as a path dependency.

• Undeprecate unsafe trait accessors. Further evaluation showed that their deprecation should be delayed until trait impl specialization is available.
• Fixed magic bytes used to detect tiff images.
• Added DynamicImage::from_decoder.
• Fixed a bug in the PNGReader that caused an infinite loop.
• Added ColorType::{bits_per_pixel, num_components}.
• Added ImageFormat::from_path, same format deduction as the open method.
• Fixed a panic in the gif decoder.
• Aligned background color handling of gif to web browser implementations.
• Fixed handling of partial frames in animated gif.
• Removed unused direct lzw dependency, an indirect dependency in tiff.

• Fixed build without no features enabled

• Fixed a variety of crashes and opaque errors in webp
• Updated the png limits to be less restrictive
• Reworked even more unsafe operations into safe alternatives
• Derived Debug on FilterType and Deref on Pixel
• Removed a restriction on DXT to always require power of two dimensions
• Change the encoding of RGBA in bmp using bitfields
• Corrected various urls

• A fairly important bugfix backport
• Fixed a potentially memory safety issue in the hdr and tiff decoders, see #885
• See the full advisory for an analysis
• Fixes ImageBuffer index calculation for very, very large images
• Fix some crashes while parsing specific incomplete pnm images
• Added comprehensive fuzzing for the pam image types