[GSOC 2025] Imgcodecs Metadata Support #27488
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asmorkalov
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Jun 27, 2025
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| typedef std::variant<int64_t, srational64_t, double, std::string, std::vector<int64_t>, | ||
| std::vector<srational64_t>, std::vector<double> > ExifTagValue; |
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Variant is not handled by Java/Python and other bindings. Need to think about it.
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Also, std::variant is not available in OpenCV 4.x, as it requires C++17.
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i have the idea that using something like ExifEntry_t struct
/**
* @brief Entry which contains possible values for different exif tags
*/
struct ExifEntry_t
{
ExifEntry_t();
std::vector<u_rational_t> field_u_rational; ///< vector of rational fields
std::string field_str; ///< any kind of textual information
float field_float; ///< Currently is not used
double field_double; ///< Currently is not used
uint32_t field_u32; ///< Unsigned 32-bit value
int32_t field_s32; ///< Signed 32-bit value
uint16_t tag; ///< Tag number
uint16_t field_u16; ///< Unsigned 16-bit value
int16_t field_s16; ///< Signed 16-bit value
uint8_t field_u8; ///< Unsigned 8-bit value
int8_t field_s8; ///< Signed 8-bit value
};
|
This PR is intended as a testbed for developing a robust Metadata handling API. |
( for all related functions ) probably instead of using |
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asmorkalov
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Jul 1, 2025
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. ### Pull Request Readiness Checklist 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 - [x] 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
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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.