Fix color channel contamination when resizing small images - #2414
Open
Hanabi9248 wants to merge 5 commits into
Open
Fix color channel contamination when resizing small images#2414Hanabi9248 wants to merge 5 commits into
Hanabi9248 wants to merge 5 commits into
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Resizing a 2×1 RGBA surface filled with
(20, 80, 160, 200)to 4×2 produces(20, 20, 20, 20). The scanline cache is shared across channels and keyed only by source row, so a short image can reuse the previous channel's filtered samples.Invalidate the cached row indices before processing each channel, while retaining the allocated buffers. Add uint8 RGB/RGBA and floating-point regressions, and include them in the CMake, Visual Studio, and Xcode unit-test projects.
Both new test cases fail before the fix and pass afterward (592 assertions). Tested on Windows with MinGW GCC 16.2, compiling the repository's Catch runner and actual image-processing sources with C++20 and LTO. A separate comparison against independently resized channels also passes for 16 combinations of pixel type, alpha, and image height. Full Cinder builds and MSVC/macOS/Linux runs were not performed.