René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Inconsistent behavior for savefig.facecolor + savefig.transparent depending on output format","articleBody":"\u003c!--To help us understand and resolve your issue, please fill out the form to the best of your ability.--\u003e\r\n\u003c!--You can feel free to delete the sections that do not apply.--\u003e\r\n\r\n### Bug report\r\n\r\n**Bug summary**\r\n\r\nSetting both savefig.facecolor and savefig.transparent behaves differently depending on whether the image is saved as jpeg or png.\r\n\r\n**Code for reproduction**\r\n\r\nmodified from test_image.test_jpeg_alpha\r\n\r\n```python\r\nfrom pylab import *\r\nrcdefaults()\r\n\r\nplt.figure(figsize=(1, 1), dpi=300)\r\n# Create an image that is all black, with a gradient from 0-1 in\r\n# the alpha channel from left to right.\r\nim = np.zeros((300, 300, 4), dtype=float)\r\nim[..., 3] = np.linspace(0.0, 1.0, 300)\r\n\r\nplt.figimage(im)\r\n\r\nwith rc_context({'savefig.facecolor': 'red', 'savefig.transparent': True}):\r\n    plt.savefig(\"/tmp/test.jpg\")\r\n    plt.savefig(\"/tmp/test.png\")\r\n```\r\n\r\n**Actual outcome**\r\n\r\ntest.png\r\n![test](https://user-images.githubusercontent.com/1322974/33534827-d28786ae-d85e-11e7-9c74-b3aa8525a74b.png)\r\n\r\ntest.jpg\r\n![test](https://user-images.githubusercontent.com/1322974/33534829-d6dcdab0-d85e-11e7-95db-fba753f87f9a.jpg)\r\n\r\n\r\n**Expected outcome**\r\n\r\nSome consistent behavior across formats (the fact that jpeg cannot represent transparency should not prevent either both files to have a red background or both files not to have a red background).\r\n\r\nI plan to deprecate savefig.facecolor/savefig.edgcolor/savefig.transparent anyways (see #9080, #9698); mostly just noting the issue in the meantime.\r\n\r\n**Matplotlib version**\r\n\u003c!--Please specify your platform and versions of the relevant libraries you are using:--\u003e\r\n  * Operating system:\r\n  * Matplotlib version: master and 2.1\r\n  * Matplotlib backend (`print(matplotlib.get_backend())`):\r\n  * Python version:\r\n  * Jupyter version (if applicable):\r\n  * Other libraries: \r\n\r\n\u003c!--Please tell us how you installed matplotlib and python e.g., from source, pip, conda--\u003e\r\n\u003c!--If you installed from conda, please specify which channel you used if not the default--\u003e\r\n\r\n","author":{"url":"https://github.com/anntzer","@type":"Person","name":"anntzer"},"datePublished":"2017-12-04T03:21:51.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":1},"url":"https://github.com/9921/matplotlib/issues/9921"}