Fix: support alpha array for RGB images in imshow (closes #26092) #30111
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Hi @Vaishnavi-Raghupathi we do usually require new tests for code changes. Also, some of the existing tests are broken by this change, which needs to be addressed.
The issue has moved on a fair bit since it was opened. I believe the most important comment to read is #26092 (comment). You should check what the code in there produces with and without your change. I believe the remaining work is to make the bottom right subplot look like the centre right subplot, i.e. when we have an RGBA array and an alpha array passed in, the alpha of these two arrays should be blended.
| # user-specified array alpha overrides the existing alpha channel | ||
| A = np.dstack([A[..., :3], alpha]) | ||
| else: # Scalar alpha | ||
| if A.shape[2] == 3: # broadcast scalar alpha | ||
| A = np.dstack([A, np.full(A.shape[:2], alpha, np.float32)]) | ||
| else: # or apply scalar alpha to existing alpha channel | ||
| post_apply_alpha = True |
| post_apply_alpha = True | ||
| #to handle RGBA inputs | ||
| if A.shape[2] == 4 and alpha is not None: | ||
| A[..., 3] = alpha # override existing alpha channel |
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I think this is just repeating what already happened on line 518.
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These changes do not belong in this PR.
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I'm going to mark this as "draft" for now. Please mark it as "ready for review" when you are ready. In the meantime, if you need help, feel free to ask questions here. Or you may prefer to ask them in our incubator gitter room. |
-->Summary
This PR fixes issue #26092 by enabling the use of a 2D alpha array with RGB images in
imshow. Previously, passing an alpha array worked for grayscale images but was ignored for RGB images. With this change, the alpha array is correctly combined with the RGB data, allowing for per-pixel transparency in color images.--> What was changed
--> How it was tested
--> Additional notes
Closes #26092