Drop alpha channel when saving comparison failure diff image. #11075
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timhoffm
approved these changes
Apr 18, 2018
lib/matplotlib/testing/compare.py
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| @@ -422,8 +422,8 @@ def compare_images(expected, actual, tol, in_decorator=False): | |||
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| def save_diff_image(expected, actual, output): | |||
| expectedImage = _png.read_png(expected) | |||
| actualImage = _png.read_png(actual) | |||
| expectedImage = _png.read_png(expected)[..., :3] | |||
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# drop alpha channel
We drop (for the better or the worse) the alpha channel when *comparing* the images (in `compare_images`), but not when saving; thus, a comparison failure where additionally the reference has no alpha but the generated image has an alpha channel would so far raise a spurious "image sizes do not match" when trying to save the diff image, rather than actually saving the diff image as expected. Noted while running the Matplotlib test suite with mplcairo.
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jklymak
approved these changes
Apr 18, 2018
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We drop (for the better or the worse) the alpha channel when comparing
the images (in
compare_images), but not when saving; thus, acomparison failure where additionally the reference has no alpha but
the generated image has an alpha channel would so far raise a spurious
"image sizes do not match" when trying to save the diff image, rather
than actually saving the diff image as expected.
Noted while running the Matplotlib test suite with mplcairo.
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