From 855332acc95ea5bf893b5ee9f0270e2a1b2d4fbb Mon Sep 17 00:00:00 2001 From: tfpf <19171016+tfpf@users.noreply.github.com> Date: Fri, 8 Jul 2022 11:35:39 +0530 Subject: [PATCH] Fixed SVG-as-text image comparison tests. SVG-as-text tests make make the figure background transparent, but its colour (i.e. under the transparent mask) is actually black. Before the expected and actual images are compared, they are converted from RGBA to RGB, which makes them both completely black (since the text is also black). As a result, the test passes even if the expected and actual images differ. Not ignoring the transparency layer fixes this problem: discard the transparency layer (if any) only if the image is opaque. --- lib/matplotlib/testing/compare.py | 21 +- .../bbox_inches_tight_suptile_legend.svg | 1546 +++++++++-------- 2 files changed, 814 insertions(+), 753 deletions(-) diff --git a/lib/matplotlib/testing/compare.py b/lib/matplotlib/testing/compare.py index 665e055f123a..4afb3c6ecea2 100644 --- a/lib/matplotlib/testing/compare.py +++ b/lib/matplotlib/testing/compare.py @@ -371,6 +371,16 @@ def calculate_rms(expected_image, actual_image): # 16-bit depth, as Pillow converts these to RGB incorrectly. +def _load_image(path): + img = Image.open(path) + # In an RGBA image, if the smallest value in the alpha channel is 255, all + # values in it must be 255, meaning that the image is opaque. If so, + # discard the alpha channel so that it may compare equal to an RGB image. + if img.mode != "RGBA" or img.getextrema()[3][0] == 255: + img = img.convert("RGB") + return np.asarray(img) + + def compare_images(expected, actual, tol, in_decorator=False): """ Compare two "image" files checking differences within a tolerance. @@ -435,9 +445,9 @@ def compare_images(expected, actual, tol, in_decorator=False): actual = convert(actual, cache=True) expected = convert(expected, cache=True) - # open the image files and remove the alpha channel (if it exists) - expected_image = np.asarray(Image.open(expected).convert("RGB")) - actual_image = np.asarray(Image.open(actual).convert("RGB")) + # open the image files + expected_image = _load_image(expected) + actual_image = _load_image(actual) actual_image, expected_image = crop_to_same( actual, actual_image, expected, expected_image) @@ -486,9 +496,8 @@ def save_diff_image(expected, actual, output): output : str File path to save difference image to. """ - # Drop alpha channels, similarly to compare_images. - expected_image = np.asarray(Image.open(expected).convert("RGB")) - actual_image = np.asarray(Image.open(actual).convert("RGB")) + expected_image = _load_image(expected) + actual_image = _load_image(actual) actual_image, expected_image = crop_to_same( actual, actual_image, expected, expected_image) expected_image = np.array(expected_image).astype(float) diff --git a/lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight_suptile_legend.svg b/lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight_suptile_legend.svg index c99489ca7dfb..5cf932d60cb7 100644 --- a/lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight_suptile_legend.svg +++ b/lib/matplotlib/tests/baseline_images/test_bbox_tight/bbox_inches_tight_suptile_legend.svg @@ -1,21 +1,32 @@ - -