AcademySoftwareFoundation/OpenImageIO v2.3.7.2

OpenImageIO 2.3.7.2

on GitHub

Release 2.3 (1 Sept 2021) -- compared to 2.2

New minimum dependencies and compatibility changes:

• C++ standard: C++14 is now the minimum (gcc 6.1 - 11.2, clang 3.4 - 12,
  MSVS 2017 - 2019, icc 17+). The default C++ standard mode, if none is
  explicitly specified, is now C++14. #2918 (2.3.4) #2955 #2977 (2.3.5)
• FFMmpeg (optional) dependency minimum is now 3.0 (raised from 2.6). #2994
• OpenCV (optional) dependency minimum is now 3.0 (raised from 2.0). #3015

New major features and public API changes:

• Changes and clarifications to geterror() in all classes that have one:
  • geterror() now takes an optional clear parameter controls if the
    pending error is cleared as well as retrieved (default true).
  • All classes with geterror() are ensured to have has_error().
  • geterror() appends to the pending error message, if one is already
    present but not retrieved. Appending errors will be automatically
    separated by newlines, also any newline at the end of a geterror
    call will be stripped. #2740 (2.3.0.1)
• ImageInput error messages are now thread-specific. This prevents multiple
  threads simultaneously reading from the same ImageInput from getting the
  other thread's error messages. But it means you must always retrieve an
  error with getmessage() from the same thread that made the read call
  that generated the error. #2752 (2.3.0.1)
• ImageInput and ImageOutput have removed several fields (like the m_mutex)
  and instead now use a PIMPL idiom that hides internals better from the
  ABI. If you had a custom ImageInput/Output class that directly accessed
  the m_mutex, replace it instead with calls to ImageInput::lock() and
  unlock() (and ImageOutput). #2752 (2.3.1.0)
• Clarify that ImageBuf methods subimage(), nsubimages(), miplevel(),
  nmipevels(), and file_format_name() refer to the file that an ImageBuf
  was read from, and are thus only meaningful for ImageBuf's that directly
  read from files. "Computed" or copied ImageBuf's are solo images in memory
  that no longer correspond to a file even if the input to the computation
  was from a file. #2759 (2.3.0.1/2.2.9)
• New get_extension_map() returns a map that list all image file formats
  and their presumed file extensions. #2904 (2.3.4)
• Overhaul of how we handle "thumbnails" (small preview images embedded in
  the headers of some image file formats) #3021 (2.3.7):
  • Thumbnails no longer embedded in the ImageSpec as "thumbnail_image"
    metadata of a big character array blob.
  • ImageInput, ImageBuf, and ImageCache have varieties of get_thumbnail()
    method that returns the thumbnail as an ImageBuf. If this is not
    called, ideally the reader will not undergo the expense of reading and
    storing thumbnail data.
  • ImageOutput and ImageBuf have set_thumbnail() to communicate a
    thumbnail image as an ImageBuf.
  • The net effect is that reading files and retrieving ImageSpec's should
    be more efficient for apps that don't have a use for thumbnails.
• Significant improvements to UDIM handling in ImageCache/TextureSystem:
  • New UDIM texture name patterns recognized: %(UDIM)d is the Houdini
    convention, and _u##v## is for Animal Logic's internal renderer.
    #3006 (2.2.16/2.3.6)
  • It is now permissible for get_texture_info()/get_image_info() to
    retrieve metadata for UDIM patterns -- previously it failed, but now
    it will succeed in retrieving any metadata as long as it is present
    and has the same value in all the matching "UDIM tile" panels. #3049
    (2.3.7)
  • TextureSystem now exposes methods is_udim(), resolve_udim(),
    inventory_udim() that should be helpful for apps dealing with UDIM
    textures. See the documentation for details. #3054 (2.3.7)
  • Performance improvements when using UDIM textures. #3049 (2.3.7)
• ImageBuf, when "wrapping" an app-owned buffer, now allows explicit
  specification of stride lengths. This allows you to wrap a buffer that
  has internal padding or other non-contiguous spacing of pixels, scanlines,
  or image planes. #3022 (2.3.6)
• oiiotool new commands and options:
  • --pastemeta takes two images as arguments, and appends all the
    metadata (only) from the first image onto the second image's pixels
    and metadata, producing a combined image. #2708 (2.3.0.0)
  • --chappend and --siappend both allow an optional modifier :n=
    to specify the number of images from the stack to be combined
    (default n=2). #2709 (2.3.0.0)
  • --fit now takes an additional optional modifier: fillmode= with
    choices of letterbox (default), width, and height. #2784 (2.3.2.0)
  • --autocc now has an optional modifier :unpremult=1 that causes
    any color transformations related to autocc to unpremultiply by alpha
    before the transformation and then re-premultiply afterwards, exactly
    the same control that exists for individual --colorconvert but never
    existed for autocc. #2890 (2.3.3)
  • --list-formats lists all the image file formats that OIIO knows
    about, and for each, the associated file extensions. #2904 (2.3.4)
  • --skip-bad-frames causes an error (such as an input file not being
    found) to simply skip to the next frame in the frame range loop, rather
    that immediately exiting. #2905 (2.3.4)
  • When doing expression substitution, {getattribute(name)} will be
    replaced by the value that OIIO::getattribute(name, ...) would
    retrieve. #2932 (2.3.4)
  • --missingfile (which takes a subsequent argument of error, black,
    or checker) determines the behavior when an input image file is
    missing (the file does not exist at all, does not include cases where
    the file exists but there are read errors). The default value of
    error matches the old behavior: report an error and terminate all
    command processing. Other choices of black or checker will continue
    processing but substitute either a black or checkerboard image for the
    missing file. #2949 (2.3.4)
  • --printinfo prints verbose metadata info about the current top
    image on the stack. #3056 (2.3.7)
  • --printstats prints statistics about the current top image on the
    stack, and optionally can limit the statistics to a rectangular
    subregion of the image. #3056 (2.3.7)
  • Expanded expression now support the following new metadata notations:
    META, METABRIEF, and STATS. #3025 (2.3.6)
  • --mosaic now takes optional fit=WxH modifier that lets you set the
    "cell" size, with all constituent images resized as needed (similarly
    to if you used --fit on each individually). This is helpful for
    creating contact sheets without having to resize separately or to know
    the resolution of the original images. #3026 (2.3.6)
  • REMOVED --histogram which had been deprecated and undocumented since
    before OIIO 2.0. #3029 (2.3.6)
• Python bindings:
  • When transferring blocks of pixels (e.g., ImageInput.read_image()
    or ImageOutput.write_scanline()), "half" pixels ended up mangled
    into uint16, but now they use the correct numpy.float16 type. #2694
    (2.3.0.0)
  • The value passed to attribute(name, typedesc, value) can now be a
    tuple, list, numpy array, or scalar value. #2695 (2.3.0.0)
  • Added Python bindings for the TextureSystem. #2842
  • Add the previously (inadvertently) omitted enum value for
    ImageBufAlgo.MakeTxBumpWithSlopes. #2951 (2.3.4)
• Environment variables:
  • CUE_THREADS env variable, if set, is now honored to set the default
    size of the OIIO thread pool. This helps to make OIIO-based apps be
    good citizens when run as OpenCue jobs. #3038 (2.3.7)
• Library organization:
  • All the utility classes are now in libOpenImageIO_Util only and
    libOpenImageIO depends on and links to libOpenImageIO_Util, rather
    than the utility classes being defined separately in both libraries.
    #2906 (2.3.4)
  • Include file change: imagebuf.h no longer includes imagecache.h.
    It should never have needed to, since it didn't need any of its
    declarations. Other code that should always have included both headers,
    but inadvertently only included imagebuf.h, may now need to add an
    explicit #include <OpenImageIO/imagecache.h>. #3036 (2.3.7)
• Important change to Makefile wrapper: We have a 'Makefile' that just wraps
  cmake for ease of use. This has changed its practice of putting builds in
  build/ARCH to just build (and local installs from dist/ARCH to dist)
  to better match common cmake practice. So where your local builds end up may
  shift a bit. #3057 (2.3.7)
• Deprecations: A number of long-deprecated functions and methods have been
  given deprecation attributes that will cause warnings if you use them. They
  will eventually be removed entirely at the next "breaking" release (3.0,
  whenever that is). #3032 (2.3.7)

Performance improvements:

• Speed up BMP reading by eliminating wasteful allocation and copying
  done on each scanline read. #2934 (2.3.4)
• For IBA::to_OpenCV(), improve efficiency for certain image copies. #2944
  (2.3.4)
• Fix runaway parsing time for pathological XMP metadata. #2968 (2.3.5/2.2.15)
• TextureSystem reduction in overhead when using UDIM textures. #3049 (2.3.7)

Fixes and feature enhancements:

• Fix a situation where if an ImageBuf backed by an ImageCache reads an
  image, then the image changes on disk, then another ImageBuf or ImageCache
  tries to read it, it could end up with the old version. This involved some
  strategic cache invalidation when ImageBuf's write images to disk. #2696
  (2.3.0.0)
• Improve parsing of XMP records in metadata: more correct handling of
  lists/sequences, better inference of types that look like int or float
  (rather than forcing unknown fields into strings), fixed bugs in parsing
  rational values. #2865 (2.2.12/2.3.3)
• ImageBuf/ImageBufAlgo:
  • IBA::contrast_remap() fixes bug that could crash for very large
    images #2704 (2.3.0.0)
  • Fix stack overflow crash in IBA::colorconvert of unusually wide images.
    #2716 (2.3.0.1/2.2.8)
  • Fix IBA::make_texture() incorrectly setting tile sizes. #2737
    (2.3.0.1/2.2.8)
  • IBA::make_texture() now correctly propagates error messages, which
    can be retrieved via the global OIIO::geterror() call. #2747 (2.3.0.1)
  • IBA::fit() now takes a fillmode parameter that controls exactly
    how the resize will occur in cases where the aspect ratio of the new
    frame doesn't exactly match that of the source image. The old way (and
    the default value now) is "letterbox", but now also "width" and
    "height" modes are allowed. See fit() documentation for details.
    #2784 (2.3.2.0)
  • IBA::fit() fixes some slight ringing at image edges when using a
    combination of black wrap mode and a filter with negative lobes.
    #2787 (2.3.2.0)
  • Fix: ociolook() and ociofiletransform() internally reversed the
    order of their inverse and unpremult arguments, making it hard to
    select the inverse transformation. #2844 (2.3.3/2.2.11)
  • Fix crash for certain calls to ImageBuf::set_write_format() when
    writing files that support per-channel data types. #2885 (2.3.3)
  • Fix: IBA::fillholes_pushpull did not correctly understand which
    channel was alpha when generating subimages. #2939 (2.3.4)
  • Fix: IBA::render_text did not properly account for non-1 alpha of
    the text color. #2981 (2.3.5/2.2.15)
  • IBA::colorconvert, colormatrixtransform, ociolook, ociodisplay,
    and ociofiletransform have been fixed so that if input is more than
    4 channels, the additional channels will be copied unchanged, rather
    than inadvertently set to 0. #2987 (2.3.5/2.2.16)
  • Thread safety has been improved for ImageBuf::init_spec() and read()
    (though no problem was ever reported in the wild). #3018 (2.3.6)
  • render_text() now accepts text strings with embedded linefeeds and
    will turn them into multiple lines of rendered text. #3024 (2.3.6)
• ImageCache/TextureSystem/maketx:
  • Fix ImageCache bug: add_tile/get_tile not properly honoring when
    chend < chbegin it should get all channels. #2742 (2.3.0.1/2.2.8)
  • ImageBufAlgo::make_texture() (as well as maketx and oiiotool -otex)
    clamp half values to their maximum finite range to prevent very large
    float inputs turning into Inf when saved as half values. #2891 (2.3.3)
  • Fix crash when sampling non-zero-base channels. #2962 (2.3.5/2.2.15)
  • IBA::make_texture() rejects "deep" input images, since they cannot
    be made into textures. Doing this could previously crash. #2991
    (2.3.5/2.2.16)
  • maketx and oiiotool -otex have fixed double printing of error
    messages #2992 (2.3.5).
  • Making bumpslopes textures now allows scaled slopes UV normalization.
    This is exposed as new maketx argument --uvsopes_scale, or passing
    the attribute uvslopes_scale (int) to make_texture(). #3012 (2.3.6)
  • There is a new variety of ImageCache::invalidate() that takes an
    ImageHandle* argument instead of a filename. #3035 (2.3.7)
• oiiotool:
  • --resize of images with multi-subimages could crash. #2711 (2.3.0.0)
  • Improve oiiotool's guessing about the desired output format based on
    inputs (in the absence of -d to specify the format). #2717
    (2.3.0.1/2.2.8)
  • --text now accepts text strings with embedded linefeeds and
    will turn them into multiple lines of rendered text. #3024 (2.3.6)
• BMP
  • Fix reading BMP images with bottom-to-top row order. #2776
    (2.3.1.1/2.2.9)
  • Correctly read BMP images of the older V1 variety without crashing.
    #2899 (2.3.3/2.2.13)
  • Fix error in the rightmost pixel column when reading 4 bpp images with
    odd horizontal resolution. #2899 (2.3.3/2.2.13)
  • BMP reads now return metadata "bmp:bitsperpixel" (only when not 24
    or 32) to indicate non-whole-byte channels sizes in the file, and
    "bmp:version" to indicate the version of the BMP format. #2899
    (2.3.3/2.2.13)
  • Speed up BMP reading by eliminating wasteful allocation and copying
    done on each scanline read. #2934 (2.3.4)
  • For BMP files that are 8 bits per pixel and all palette entries have
    R == G == B values, read the file as an 8-bit grayscale image instead
    of needlessly promoting to a full RGB 3-channel image. #2943 (2.3.4)
  • Full support for reading RLE-compressed BMP images. #2976 (2.3.5/2.2.15)
  • Write single channel BMP as 8 bit palette images. #2976 (2.3.5/2.2.15)
• DPX
  • Output to DPX files now supports IOProxy. (Input already did.) #3013
    (2.2.17/2.3.6)
• FFMpeg/movies:
  • Avoid potential crash when a frame can't be read. #2693 (2.3.0.0)
  • Several varieties of encoded videos with 12 bits per channel and
    having alpha were incorrectly reported as 8 bits and without alpha.
    #2989 (2.3.5/2.2.16)
• GIF
  • Support UTF-8 filenames on Windows for GIF files. #2777 (2.3.2.0)
  • Fix error checking for non-existant GIF files. #2886 (2.3.3)
• HEIC
  • Fix error decoding Apple HEIF files. #2794/#2809 (2.3.2.0)
  • Better valid_file() check for HEIF. #2810 (2.3.2.0)
  • Enabled AVIF decoding of heic files (requires libheif >= 1.7 and for
    it to have been built with an AV1 encoder/decoder). #2811 #2812 #2814
    #2818 (2.3.3.0)
• IFF
  • Fix broken reads of 16 bit iff files. #2736 (2.3.0.1/2.2.8)
• JPEG
  • Allow reading of JPEG files with mildly corrupted headers. #2927 (2.3.4)
• OpenEXR:
  • Fix rare crash that was possible when multithreaded writing openexr
    files. #2781 (2.3.2.0)
  • Improved error reporting when errors are encountered writing OpenEXR
    files. #2783 (2.3.2.0)
  • Fix potential crash parsing OpenEXR header that contains Rational
    attributes with certain values. #2791 (2.2.10/2.3.2)
  • EXPERIMENTAL: When building against OpenEXR 3.1, the OIIO CMake option
    -DOIIO_USE_EXR_C_API=ON will use a new OpenEXR API that we think
    will allow higher performance texture reads in a multithreaded app.
    This has not yet been benchmarked or tested thoroughly. #3009 #3027
    (2.3.6)
  • The reader no longer renames file metadata "version" into the special
    "openexr:version" that would indicate the OpenEXR file format version
    of the file. That's never what it meant! It really was just arbitrary
    metadata. #3044 (2.3.7)
• PNG
  • Read Exif data from PNG files. #2767 (2.3.1.1/2.2.9)
• PSD
  • Add support for reading ISD profiles for PSD input. #2788 (2.3.2.0)
  • Fix loading PSB files with cinf tags. #2877 (2.2.12/2.3.2)
• RAW:
  • Additional input configuration hints to control options in the
    underlying LibRaw: "raw:user_flip" #2769 (2.3.1.0)
    "raw:balance_clamped", "raw:apply_scene_linear_scale",
    "raw:camera_to_scene_linear_scale" #3045 (2.3.7)
  • Correctly handle RAW files with Unicode filenames on Windows. #2888
    (2.3.3)
  • Fix garbled output when raw:Demosaic hint is "none". #3045 (2.3.7)
• Targa
  • Fix potential crash when reading files with no thumbnail. #2903
    (2.3.3/2.2.13)
  • Fix alpha handling for some files. #3019 (2.3.6)
• TIFF:
  • Fix broken reads of multi-subimage non-spectral files (such as
    photometric YCbCr mode). #2692 (2.3.0.0)
  • Fix spec() and spec_dimensions() for MIPmapped TIFF files, they did
    not recognize being asked to return the specs for invalid subimage
    indices. #2723 (2.3.0.1/2.2.7)
  • Add ability to output 1bpp TIFF files. #2722 (2.3.0.1/2.2.7)
  • Fix reading TIFF files with "separate" planarconfig and rowsperstrip
    more than 1. #2757 (2.3.0.1/2.2.9)
  • Fix incorrect reading of tiled TIFF files using certain rare TIFF
    features that also have a vertical resolution that is not a whole
    multiple of the tile size. #2895 (2.3.3/2.2.13)
  • Support IOProxy for reading TIFF files. #2921 (2.3.4)
  • TIFF plugin now properly honors caller request for single-threaded
    operation. #3016 (2.3.6)
• WebP:
  • Add support for requesting compression "lossless". #2726 (2.3.0.1/2.2.8)
  • Input improvements including: RGB images are kept as RGB instead of
    always adding alpha; more efficient by skipping alpha premultiplication
    when it's unnecessary; now can read animated WebP images as
    multi-subimage files. #2730 (2.3.0.1/2.2.8)
• Fix memory leak during decoding of some invalid Exif blocks. #2824
• Fix possible divide-by-zero error in read_image/read_scanlines for invalid
  image sizes (usually from corrupt files). #2983 (2.3.5/2.2.16)

Developer goodies / internals:

• Internals now use C++11 final keywords wherever applicable. #2734
  (2.3.0.1)
• More internals conversion of old Strutil::sprintf to Strutil::fmt::format
  and related changes. #2889 (2.3.3)
• Redundant format conversion code removed from imageio.cpp #2907 (2.3.4)
• Eliminate direct output to std::cerr and std::cout by library calls.
  #2923 (2.3.4)
• argparse.h:
  • ArgParse::abort() lets the response to a command line argument signal
    that no further arguments should be parsed. #2820 (2.3.3/2.2.11)
• color.h:
  • New ColorConfig::OpenColorIO_version_hex() returns the hex code for
    the version of OCIO we are using (0 for no OCIO support). #2849 (2.3.3)
• farmhash.h:
  • Clean up all non-namespaced preprocessor symbols that are set
    by this header and may pollute the caller's symbols. #3002 (2.2.16/2.3.6)
• filesystem.h:
  • New Filesystem::generic_filepath() returnss a filepath in generic
    format (not OS specific). #2819 (2.3.3/2.2.11)
  • Improve exception safety in Filesystem directory iteration. #2998
    (2.2.16/2.3.6)
  • New filename_to_regex() makes a filename "safe" to use as a
    regex pattern (for example, properly backslashing any . characters).
    #3046 (2.3.7)
  • Some methods that used to take a const std::string& now take a
    string_view. #3047 (2.3.7)
• fmath.h:
  • Use CPU intrinsics to speed up swap_ending (by 8-15x when swapping
    bytes of large arrays). #2763 (2.3.1.0)
• hash.h:
  • farmhash::inlined::Hash now is constexpr and works for Cuda.
    #2843 (2.3.3) #2914 #2930 (2.3.4)
• oiioversion.h:
  • New macros OIIO_VERSION_GREATER_EQUAL and OIIO_VERSION_LESS.
    #2831 (2.3.3/2.2.11)
• platform.h:
  • New macro OIIO_INLINE_CONSTEXPR, equivalent to inline constexpr for
    C++17, but just constexpr for C++ <= 14. #2832 (2.3.3/2.2.11)
• simd.h:
  • Fix incorrect ARM NEON code in simd.h. #2739 (2.3.0.1/2.2.8)
• span.h:
  • std::size() and std::ssize() should work with OIIO::span now.
    #2827 (2.3.3/2.2.11)
• string_view.h:
  • std::size() and std::ssize() should work with OIIO::string_view
    now. #2827 (2.3.3/2.2.11)
  • More thorough constexr of string_view methods. #2841 (2.3.3)
• strongparam.h:
  • New StrongParam helper for disambiguating parameters. #2735 (2.3.2)
• strutil.h:
  • Strutil splits() and splitsv() should return no pieces when passed
    an empty string. (It previously erroneously returned one piece
    consisting of an empty string.) #2712 (2.3.0.0)
  • Fix build break when strutil.h was included in Cuda 10.1 code. #2743
    (2.3.0.1/2.2.8)
  • strhash() is now constexpr for C++14 and higher. #2843 (2.3.3)
  • New Strutil functions: find, rfind, ifind, irfind #2960 (2.3.4/2.2.14)
    contains_any_char #3034 (2.3.7) rcontains, ircontains #3053 (2.3.7)
• sysutil.h:
  • Extend getenv() to take a default if the environment variable is not
    found. #3037 #3040 (2.3.7)
• typedesc.h:
  • TypeDesc::basetype_merge(a,b) returns a BASETYPE having the
    precision and range to hold the basetypes of either a or b.
    #2715 (2.3.0.0)
  • TypeDesc can now describe 2D and 3D bounding boxes, as arrays of 2
    VEC2 aggregates (for 2D) or VEC3 aggregates (for 3D) with "BOX"
    semantic. The shorthand for these are TypeBox2, TypeBox3 (for
    float), and TypeBox2i and TypeBox3i for integer or pixel coordinte
    boxes. #3008 (2.2.17/2.3.6)
• unordered_map_concurrent.h:
  • New methods find_or_insert, nobin_mask(). #2867 (2.2.12/2.3.3)
• ustring.h:
  • ustring internals now have a way to ask for the list of ustrings whose
    hashses collided. #2786 (2.2.11/2.3.2.0)
  • ustring now guarantees that no two ustrings will return the exact same
    value for hash(). #2870 (2.3.3)

Build/test system improvements and platform ports:

• CMake build system and scripts:
  • Instead of defaulting to looking for Python 2.7, the OIIO build now
    defaults to whatever Python is found (though a specific one can still
    be requested via the PYTHON_VERSION variable). #2705 (2.3.0.0/2.2.8)
    #2764 (2.3.0.1/2.2.8)
  • Make the OIIO CMake files work properly if OIIO is a subproject. Also
    various other CMake script refactoring. #2770 (2.3.1.1/2.2.9)
  • Extend checked_find_package with VERSION_MIN and VERSION_MAX #2773
    (2.3.1.1/2.2.9), DEFINITIONS and SETVARIABLES #3061 (2.3.7)
  • No longer directly link against python libraries when unnecessary.
    #2807 (2.2.11/2.3.3)
  • On Windows, fix some linkage problems by changing the pybind11
    bindings to make a CMake "shared" library rather than "module". Sounds
    wrong, but seems to work. We will reverse if this causes problems.
    #2830 (2.3.3/2.2.11)
  • Improvements to building or linking static libraries. #2854 (2.2.12/2.3.3)
  • Change default STOP_ON_WARNING to OFF for release branches (including
    this one) so that small change in compiler warnings after our release
    don't break anybody's builds. (Though we still stop on warnings for CI
    builds). #2861 (2.2.12/2.3.3)
  • The pkgconfig OpenImageIO.pc was specifying the include path
    incorrectly. #2869 (2.2.12/2.3.3)
  • Support for CMake 3.20. #2913 #2931 (2.3.4)
  • Be sure to have the namespace include the patch number for pre-release
    builds from the master branch. #2948 (2.3.4)
  • Use modern style cmake targets for PNG and ZLIB dependencies. #2957
    (2.3.4)
  • Propagate C++14 minimum requirement to downstream projects via our
    cmake config exports. #2965 (2.3.5)
  • Fix exported cmake config files, which could fail if Imath and OpenEXR
    weren't the at the same version number. #2975 (2.3.5/2.2.15)
  • Change default postfix for debug libraries to _d. (2.3.5)
  • Our CMake checked_find_package is now able to be requested to favor
    an exported config file, if present, on a package-by-package basis.
    #2984 (2.3.5/2.2.15)
  • If a package is requested to be disabled, skip its related tests rather
    than reporting them as broken. #2988 (2.3.5/2.2.16)
  • Better support for running testsuite when the build dir in odd places.
    #3065 #3067 (2.3.7.1)
  • To prevent accidental overwrite of sensitive areas (such as
    /usr/local), you now need to explicitly set CMAKE_INSTALL_PREFIX if you
    want the "install" to not be local to the build area. #3069 (2.3.7.1)
• Dependency version support:
  • C++20 is now supported. #2891 (2.3.3)
  • Fix deprecation warnings when building with very new PugiXML versions.
    #2733 (2.3.0.1/2.2.8)
  • Fixes to build against OpenColorIO 2.0. #2765 (2.3.0.1/2.2.8) #2817
    #2849 (2.3.3/2.2.11) #2911 (2.3.4)
  • Fix to accommodate upcoming OpenColorIO 2.1 deprecation of
    parseColorSpaceFromString. #2961 (2.3.5/2.2.15)
  • Work to ensure that OIIO will build correctly against Imath 3.0 and
    OpenEXR 3.0, as well as Imath 3.1 / OpenEXR 3.1. #2771 (2.3.1.1/2.2.9)
    #2876 #2678 #2883 #2894 (2.3.3/2.2.12) #2935 #2941 #2942 #2947 (2.3.4)
  • Better finding of OpenJpeg 2.4. #2829 (2.3.3/2.2.11)
  • On Mac, libheif 1.10 is very broken. Don't use that version. #2847
    (2.3.3/2.2.11)
  • Fix build break against changes coming in future libtiff, where it
    is changing from some libtiff-defined integer types to the equivalent
    stdint.h types. #2848 (2.3.3/2.2.11)
  • Fixes to support the libraw 202101 snapshot (their in-progress 0.21.0).
    #2850 (2.3.3/2.2.11)
  • More clear warnings about using OpenVDB 8+ when building for C++11,
    because OpenVDB 8 requires C++14 or higher. #2860 (2.2.12/2.3.3)
  • More gracefully handle building against a custom Imath/OpenEXR even
    when another exists in the system area. #2876 (2.2.12/2.3.3)
  • Minor fixes to build cleanly against the upcoming Imath 3.0. #2878
    (2.2.12/2.3.3)
  • Remove obsolete dependency on Boost random (now use std::random).
    #2896 (2.3.3)
  • libtiff 4.3 is supported. #2953 (2.3.4)
  • We now include a build_OpenJPEG.bash script that can conveniently
    build a missing OpenJPEG dependency. (2.3.5/2.2.16)
  • Changes to make it build against TBB 2021. #2985 (2.3.5/2.2.15)
  • Support for building OIIO with gcc 11. #2995 (2.2.16/2.3.6)
  • Fixes to accommodate Imath 3.1 upcoming changes. #2996 (2.2.16/2.3.6)
  • Finding FFMpeg now correctly detects the version. #2994 (2.2.16/2.3.6)
  • FFMpeg minimum version is now >= 3.0. #2999 (2.3.6)
  • Fixes for detecting and using Ptex, among other things got the version
    wrong. #3001 (2.2.16/2.3.6)
  • Fixes for building against fmt 8.0. #3007 (2.3.6)
  • The OpenCV minimum version is now >= 3.0. #3015 (2.3.6)
  • Fixes to build properly against the upcoming OpenColorIO 2.1. #3050
    (2.3.7)
  • Finding boost is more flexible when desiring static libraries. #3031
    (2.3.7/2.2.17)
  • FindTBB.cmake module updated to create proper targets. #3060 (2.3.7)
  • All the src/build_scripts/build_*.bash scripts now honor an env
    variable called DEP_DOWNLOAD_ONLY, which if set will only do the
    downloads but not the builds. #3058 #3072 (2.3.7)
  • Better finding of OpenCV on Windows. #3062 (2.3.7.1)
• Testing and Continuous integration (CI) systems:
  • Completely get rid of the old appveyor CI. #2782 (2.3.2.0)
  • Test against libtiff 4.2 in the "latest releases" test. #2792 (2.3.2.0)
  • Got Windows CI fully working, bit by bit. #2796 #2798 #2805 #2821 #2826
    #2834 #2835 #2836 #2838 #2839 #2840 (2.3.3)
  • Reduce redundant verbosty in CI output logs during dependency building.
  • Modify hash_test to verify correctness and stability of the hashes.
    #2853 (2.3.3)
  • When building custom OpenEXR with build_openexr.bash, don't have it
    build the examples. #2857 (2.2.12/2.3.3)
  • Speed up CI by using GitHub 'cache' actions + ccache. #2859 (2.2.12/2.3.3)
  • Separate stages (setup, deps, build, test) into separate GHA "steps"
    for better logging and understanding of the timing and performance.
    #2862 (2.2.12/2.3.3)
  • Now actively testing libheif in Linux CI. #2866 (2.2.12/2.3.3)
  • Remove the last vestiges of Travis-CI, which we no longer use. #2871
    (2.2.12/2.3.3)
  • For failed tests, add CMake cache and log part of the saved artifacts.
    (2.2.12/2.3.3)
  • CI now tests build in C++20 mode. #2891 (2.3.3)
  • Our CI clang-format test now uses LLVM/clang-format 11. #2966
  • Test the clang11 + C++17 combo. #3004 (2.3.6)
• Platform support:
  • Fixes for mingw. #2698 (2.3.0.0)
  • Windows fix: correct OIIO_API declaration on aligned_malloc,
    aligned_free of platform.h. #2701 (2.3.0.0)
  • Fix boost linkage problem on Windows. #2727 (2.3.0.1/2.2.8)
  • Fix warnings when compiling webpinput.cpp on 32 bit systems. #2783
    (2.3.2.0)
  • Fix problems with copysign sometimes defined as a preprocessor symbol
    on Windows. #2800 (2.3.2)
  • Fixes related to Mac M1-based systems: Fix crash in ustring internals
    #2990 (2.3.5/2.2.15.1)

Notable documentation changes:

• Make Readthedocs generate downloadable HTML as well as PDF. #2746
• Explain how to read image data into separate per-channel buffers. #2756
  (2.3.0.1/2.2.8)
• Improve use of breathe and formatting. #2762 (2.3.1.0)
• Remove documentation of deprecated ImageBufAlgo functions. #2762 (2.3.1.0)
• Document missing texture option fields. #2762 (2.3.1.0)
• Starting to use "sphinx_tabs" as a clear way to present how things should
  be done for different language bindings. #2768 (2.3.1.0)