add a check for src == dst in ocl warpTransform #25898
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I think we need a test for this scenario. |
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Sure. I'll write a test and commit it. |
mshabunin
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Add a check for src == dst in ocl warpTransform opencv#25898 As mentioned in opencv#25853, when doing WarpAffine with Mat and UMat respectively, if you force the use of the in-place operation (so that src and dst are passed the same variables), Mat produces the correct results, but UMat produces unexpected results. Obviously in-place operations are not possible with this transformation. When Mat performs the operation, if dst and src are the same variable, the function inherently makes a copy of src without telling the user. https://github.com/opencv/opencv/blob/74b50c7af05c91194469a1f059f971dff00ef889/modules/imgproc/src/imgwarp.cpp#L2831-L2834 So I did the same check in UMat, but I'm not sure if it's appropriate, should we just do a copy operation without telling the user (even if the user thinks he's doing an in-place operation), or should we throw an exception to indicate that we shouldn't pass in two same variables here? The possible reason for this problem is that there is a create function here, so it gives the developer the false impression that this create function has allocated new memory for dst, however it does not. https://github.com/opencv/opencv/blob/74b50c7af05c91194469a1f059f971dff00ef889/modules/imgproc/src/imgwarp.cpp#L2607-L2609 Because by the time the check is done here, the function has returned back. https://github.com/opencv/opencv/blob/74b50c7af05c91194469a1f059f971dff00ef889/modules/core/src/umatrix.cpp#L668-L675 ### 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. - [x] The feature is well documented and sample code can be built with the project CMake
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As mentioned in #25853, when doing WarpAffine with Mat and UMat respectively, if you force the use of the in-place operation (so that src and dst are passed the same variables), Mat produces the correct results, but UMat produces unexpected results.
Obviously in-place operations are not possible with this transformation. When Mat performs the operation, if dst and src are the same variable, the function inherently makes a copy of src without telling the user.
opencv/modules/imgproc/src/imgwarp.cpp
Lines 2831 to 2834 in 74b50c7
So I did the same check in UMat, but I'm not sure if it's appropriate, should we just do a copy operation without telling the user (even if the user thinks he's doing an in-place operation), or should we throw an exception to indicate that we shouldn't pass in two same variables here?
The possible reason for this problem is that there is a create function here, so it gives the developer the false impression that this create function has allocated new memory for dst, however it does not.
opencv/modules/imgproc/src/imgwarp.cpp
Lines 2607 to 2609 in 74b50c7
Because by the time the check is done here, the function has returned back.
opencv/modules/core/src/umatrix.cpp
Lines 668 to 675 in 74b50c7
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.