Avoid an extra copy/resample if imshow input has no alpha #27562
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
2303cda to
55fb0a1
Compare
jklymak
reviewed
Dec 23, 2023
This is probably the best we can do to fix matplotlib#27554 at this time, without delving into re-writing the Agg resampler (which, as the Python code notes, does require RGBA.)
|
This is in the |
ksunden
reviewed
Jan 9, 2024
| # No need to resample alpha or make a full array; NumPy will expand | ||
| # this out and cast to uint8 if necessary when it's assigned to the | ||
| # alpha channel below. | ||
| output_alpha = (255 * alpha) if A.dtype == np.uint8 else alpha |
There was a problem hiding this comment.
shouldn't it be multiplying by 255 if it is a float, rather than if it is a uint8?
There was a problem hiding this comment.
alpha is always a 0-1 float; if the data is uint8, then output alpha must be 0-255 instead.
ksunden
approved these changes
Jan 10, 2024
jklymak
approved these changes
Jan 10, 2024
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
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Outdated suggestions cannot be applied.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.
PR summary
This is probably the best we can do to fix #27554 at this time, without delving into re-writing the Agg resampler (which, as the Python code notes, does require RGBA.)
Also adds a test, as it appears that nothing checked an RGB input with transparent
alpha(and my original suggestion from #27554 (comment) using 255/1.0 passed tests even though it didn't work.)PR checklist