imgcodecs: png: add log if first chunk is not IHDR#27297
Merged
asmorkalov merged 2 commits intoopencv:4.xfrom May 12, 2025
Merged
imgcodecs: png: add log if first chunk is not IHDR#27297asmorkalov merged 2 commits intoopencv:4.xfrom
asmorkalov merged 2 commits intoopencv:4.xfrom
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|
cc @sturkmen72 |
sturkmen72
reviewed
May 10, 2025
modules/imgcodecs/test/test_png.cpp
Outdated
| Mat img; | ||
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| // If first is IHDR chunk, output shall not be empty. | ||
| // 8 means PNG sigunature length. |
Contributor
Author
There was a problem hiding this comment.
Thank you for your review, I fixed this and next line.
(IHDR does not expect the length of chunk data is 4.)
- // If first is IHDR chunk, output shall not be empty.
- // 8 means PNG sigunature length.
- // 4 means lenght of chunk.
+ // If IHDR chunk found as the first chunk, output shall not be empty.
+ // 8 means PNG signature length.
+ // 4 means length field(uint32_t).| // IHDR chunk shall be first. ( https://www.w3.org/TR/png-3/#5ChunkOrdering ) | ||
| id = read_chunk(m_chunkIHDR); | ||
| if (id != id_IHDR) | ||
| { |
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chatGPT suggests
if (id == id_CgBI)
{
CV_LOG_ERROR(NULL, "CgBI chunk (Apple private) found as the first chunk. IHDR is expected.");
}
else
{
CV_LOG_ERROR(NULL, "IHDR chunk shall be first. This data may be broken or malformed.");
}
Contributor
Author
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I agreed to the message change.
This fix resulted in a complicated if statement, so I flattened it.
Before
if (id != id_IHDR)
{
if (id == id_CgBI)
{
CV_LOG_ERROR(NULL, "CgBI chunk (Apple private) found as the first chunk. IHDR is expected.");
}
else
{
CV_LOG_ERROR(NULL, "IHDR chunk shall be first. This data may be broken or malformed.");
}
return false;
}After
if (id == id_CgBI)
{
CV_LOG_ERROR(NULL, "CgBI chunk (Apple private) found as the first chunk. IHDR is expected.");
return false;
}
if (id != id_IHDR)
{
CV_LOG_ERROR(NULL, "IHDR chunk shall be first. This data may be broken or malformed.");
return false;
}I have also reflected this correction in the comments of the test code. Thank you very much !
asmorkalov
approved these changes
May 12, 2025
Merged
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Close #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
Pull Request Readiness Checklist
See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request
Patch to opencv_extra has the same branch name.