SunRasterDecoder::readData() only called CvtPaletteToGray() when the
file contained a color palette (m_maptype == RMT_EQUAL_RGB). But
SunRasterEncoder always writes RMT_NONE (no palette), so gray_palette[]
stayed zero-initialized and FillGrayRow8() mapped every pixel to 0.
Fix: call CvtPaletteToGray() whenever reading as grayscale, regardless
of palette type. readHeader() already fills m_palette correctly via
FillGrayPalette() for the RMT_NONE case.
Add regression test Imgcodecs_SunRaster.imread_grayscale_roundtrip
that writes a full 0-255 ramp, reads it back with IMREAD_GRAYSCALE,
and checks NORM_INF == 0. Without the fix, NORM_INF == 255 (all black).
Remove the "broken (black result)" skip for ras in read_write_GRAYSCALE.
gdal: skip raster band mapped to an out-of-range channel in readData - #29439
Repro: read a 3-band GDT_Byte raster (no palette) whose third band is tagged `GCI_AlphaBand`, via `imread(path, IMREAD_LOAD_GDAL)`. ASan reports a heap-buffer-overflow WRITE of size 1 at `grfmt_gdal.cpp:259`.
Cause: an alpha band makes `readData` pass `color = 3`, but the `gdalChannels == 3 && image.channels() == 3` branch of `write_pixel` indexes `Vec3b[channel]` with no bound, so `channel == 3` stores one element past the 3-lane pixel. On the last pixel that lands past the Mat buffer.
Fix (per review): `readData` checks the mapped color index against `img.channels()` in the band loop, before the pixel iteration. An out-of-range band is skipped as a whole with a `CV_LOG_WARNING` naming the band and range, instead of a silent per-pixel guard. Valid RGB rasters decode identically.
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The 16-bit icvCvt_* helpers in utils.cpp move the row pointer with
step/sizeof(x[0]) - size.width*N. sizeof is unsigned, so this is done in
unsigned math. When the caller passes step == 0, it underflows to a huge
value and the pointer goes out of range, which is undefined behavior.
The TIFF decoder hits this: it walks rows itself and calls these helpers
with step = 0, so reading a 16-bit 4-channel TIFF triggers the bug.
Cast sizeof(...) to int so the math is signed. Same result for normal
calls, no overflow when the step is 0.
Added Imgcodecs_Tiff.regression_29615_16UC4 which round-trips a CV_16UC4
TIFF in memory.
This is the 4.x version of the fix, requested in
https://github.com/opencv/opencv/pull/29620 (issue #29615).
Follow-up to the recent "reject under-length raw exif profile" change.
The declared length in a PNG raw exif profile (tEXt/zTXt "Raw profile type
exif" chunk) is fully attacker controlled. The < 6 guard stops the underflow,
but a large positive value still passes it and reaches HexStringToBytes(),
which does raw_data.resize(expected_length) before reading anything. So a few
bytes in a text chunk can force a ~2GB allocation -> easy memory-amplification
DoS while decoding an otherwise small PNG.
The payload is hex encoded (two characters per byte), so a valid length can
never exceed the profile text carrying it. Reject any declared length greater
than profile_len. This bounds the allocation to the input size and doesn't
reject any valid profile; the valid decode path is unchanged.
imgcodecs(pam): fix out-of-bounds write when reading 2-channel PAM #29296
While poking at the PAM decoder I noticed basic_conversion() writes past the
end of the destination buffer when a GRAYSCALE_ALPHA (2 channel) image is read
with IMREAD_GRAYSCALE.
The 1-channel branch was written as if the destination had 3 channels:
for( ; s < end; d += 3, s += src_sampe_size )
d[0] = d[1] = d[2] = s[layout->graychan];
So for every source pixel it writes 3 bytes and advances d by 3, even though
the output row only has m_width bytes (1 channel). With m_channels == 2 that
ends up writing ~1.5 * m_width bytes per row, which runs off the row and, on
the last row, off the end of the Mat. m_width is taken straight from the file
header (up to 2^20), so the overflow size and contents are attacker controlled.
It's reachable with a plain imread(file, IMREAD_GRAYSCALE) on a crafted file.
While looking at it I also realised the loop bound was off for any multi
channel source: end was set to src + src_width, but the source has
src_width * channels samples, so it only ever processed m_width/channels pixels
instead of all of them. That's why GRAYSCALE_ALPHA / RGB_ALPHA come out only
partially filled.
Fix both at once:
- end now covers the whole row (src_width * src_sampe_size)
- the 1-channel branch writes one byte and advances d by 1
For the common grayscale->color case (channels == 1) the new end is identical
to the old one (m_width * 1 == m_width), so that path is byte for byte the same
and the existing PAM read_write test is unaffected. The only outputs that
change are the GRAYSCALE_ALPHA/RGB_ALPHA conversions, which were already broken.
Added a regression test (Imgcodecs_Pam.decode_graya_as_gray) that builds a small
2-channel PAM with an odd width, decodes it as grayscale and checks the result
matches the gray channel. It overflows/crashes on the old code and passes now.
Casting the raw integer fields ras_type and maptype directly to their
respective enum types (SunRasType / SunRasMapType) without a prior range
check is undefined behavior under C++11 §7.2/8 when the stored value falls
outside the enum's valid range.
UBSan reports:
grfmt_sunras.cpp:72: runtime error: load of value 34077, which is not a
valid value for type 'SunRasMapType'
Fix: read both fields into plain ints first, validate them against the
declared enumerator bounds, and return false (reject the image) on any
out-of-range value before performing the enum cast. This is the cheapest
correct approach — two integer comparisons added to a path that was already
doing I/O — and ensures no downstream code ever sees an ill-formed enum
value.
Add test_sunraster.cpp with regression tests covering:
- The exact crash_001 payload (invalid maptype 34077 / 0x851d)
- Invalid ras_type values
- maptype = 2 and UINT_MAX (outside [0,1])
- Truncated header
- A valid 8-bpp grayscale image that must still decode correctly
Signed-off-by: FuzzAnything fuzzanything@gmail.com
imgcodecs(png): support cICP metadata for imreadWithMetadata() #28615
Close https://github.com/opencv/opencv/issues/28606
Related https://github.com/opencv/opencv/pull/27741 (support for imwriteWithMetadata)
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Allow TIFF compression schemes for 32F#28785
Related to [https://github.com/opencv/opencv/issues/28775](https://github.com/opencv/opencv/issues/28775)
Previously, only 32FC3+SGILOG could be specified for TIFF encoding. But when floats use quantization, compression schemes can be efficient even on 32F data. This PR will allow them.
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I just don't know what kind of accuracy/performance tests should be added.
imgcodecs(webp): improve IMWRITE_WEBP_LOSSLESS_MODE to support exact lossless compression #28519Close#28503
Add IMWRITE_WEBP_LOSSLESS_MODE enum to control lossless strategy:
- IMWRITE_WEBP_LOSSLESS_OFF: Lossy compression.
- IMWRITE_WEBP_LOSSLESS_ON: Optimize/drop color in transparent pixels.
- IMWRITE_WEBP_LOSSLESS_PRESERVE_COLOR: Preserve color in transparent pixels.
Note: Currently limited to still images; animated WebP support is deferred per YAGNI.
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tiff: use a per-TIFF error handler #27927
libtiff 4.5 introduced [per-TIFF error handlers](https://libtiff.gitlab.io/libtiff/functions/TIFFOpenOptions.html). This PR removes the global OpenCV error handlers and uses per-handle error handlers. This reduces any risks associated with modifying global state, e.g. if another library also tries to set the global error handlers and OpenCV clobbers them.
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imgcodecs: bmp: relax decoding size limit to over 1GiB #27811
Close https://github.com/opencv/opencv/issues/27789
Close https://github.com/opencv/opencv/issues/23233
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imgcodecs: bmp: support to write 32bpp BMP with BI_BITFIELDS #27559
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Add strict validation for encoding parameters #27621
Close https://github.com/opencv/opencv/issues/27557
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Jpeg Metadata (iccp and xmp) #27583
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to do :
- [x] consider `m_read_options`
- [x] check if ICCP metadata is suitable to write PNG
- [x] the file `testExifOrientation_3.jpg` used in the test has an ICCP data. this data can be saved in jpg format but could not in PNG and WEBP format. Impovements to check this case with PNGEncoder and WEBPEncoder planned.
imgcodecs: fix Imgcodecs_Png.write_big test for spng #27589Close#27588
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Fixed build issue with some old GCC versions #27569
Fixes build for GCC 4.8.5 at least. Looks like the method default signature differs cross GCC versions or newer version has softer checker.
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[GSOC 2025] PNG&WebP Metadata Reading Writing Improvements #27503
Merge with https://github.com/opencv/opencv_extra/pull/1271
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Add enum IMWRITE_PNG_ZLIBBUFFER_SIZE #27551
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This patch enables users to set the internal zlib compression buffer size for PNG encoding
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imgcodecs: OpenEXR multispectral read/write support #27485
OpenCV Extra: https://github.com/opencv/opencv_extra/pull/1262/
Adds capability to read and write multispectral (>4 channels) images in OpenEXR format.
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Extend image I/O API with metadata support #27499
Covered with the PR:
* AVIF encoder can write exif, xmp, icc
* AVIF decoder can read exif
* JPEG encoder can write exif
* JPEG decoder can read exif
* PNG encoder can write exif
* PNG decoder can read exif
This PR is a sort of preamble for #27488. I suggest to merge this one first to OpenCV 4.x, then promote this change to OpenCV 5.x and then provide extra API to read and write metadata in 5.x (or maybe 4.x) in a style similar to #27488. Maybe in that PR exif packing/unpacking should be done using a separate external API. That is, metadata reading and writing can/should be done in 2 steps:
* [1] pack and then [2] embed exif into image at the encoding stage.
* [1] extract and then [2] unpack exif at the decoding stage.
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Fix for 2 channel PNGs #27469closes#26825
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Fixing imread() function 16 bit reading png problem with libspng #27113
The purpose of the PR was to load bit-exact compatible results with libspng and libpng. To test this, `Imgcodecs_Png_PngSuite `was improved. Files containing gamma correction were moved to a separate test called `Imgcodecs_Png_PngSuite_Gamma `because the logic created for the other files did not apply to those with gamma correction. As a result, libspng now works in bit-exact compatibility with libpng. The code can be refactored later.
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Changes about when APNG has a hidden frame #27127
closes : #27074
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imread: GDAL multi-channel support #27458
- tested on 30-channel FITS and 186-channel ENVI files
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imgcodecs: jpegxl: support lossless compression #27384
Close https://github.com/opencv/opencv/issues/27382
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imgcodecs: png: add log if first chunk is not IHDR #27297
Close https://github.com/opencv/opencv/issues/27295
To optimize for the native pixel format of the iPhone's early PowerVR GPUs, Apple implemented a non-standard PNG format.
Details: https://theapplewiki.com/wiki/PNG_CgBI_Format
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imgcodecs: gif: support animated gif without loop #26971Close#26970
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Test for in-memory animation encoding and decoding #27013
Tests for https://github.com/opencv/opencv/pull/26964
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APNG encoding optimization #26849
related #26840
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Imgcodecs: gif: support Disposal Method #26930
Close https://github.com/opencv/opencv/issues/26924
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Add a test related IMWRITE_PNG_COMPRESSION parameter #26973
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See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [x] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [x] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
