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{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"imshow alpha interpolation looks wrong","articleBody":"Hi, not much of an issue, but it seems that `imshow` is not interpolating RGBA images in the proper way. There was some discussion about a similar issue in #9906 which ended up on a documentation note:\r\n\r\n\u003e imshow expects RGB images adopting the straight (unassociated) alpha representation.\r\n\r\nIf that's the case `imshow` should still switch to associated colors (premultiply alpha) before interpolation to avoid artefacts like the one below, shouldn't it?\r\n\r\n```\r\nimport matplotlib.pyplot as plt\r\nimport numpy as np\r\n\r\nfig, (axl, axr) = plt.subplots(1, 2)\r\n\r\n# full green image\r\nimg = np.zeros((5, 5, 4))\r\nimg[...,1] = np.ones((5, 5))\r\n# transparent above main diagonal\r\nimg[...,3] = np.tril(np.ones((5, 5), dtype=np.uint8))\r\n\r\naxl.imshow(img, interpolation=\"none\")\r\naxr.imshow(img, interpolation=\"bilinear\")\r\n\r\nplt.show()\r\n```\r\n\r\n![bug](https://user-images.githubusercontent.com/133750/40577662-a7ca9184-6109-11e8-99c6-3201b98c8c78.png)\r\n\r\n","author":{"url":"https://github.com/fargiolas","@type":"Person","name":"fargiolas"},"datePublished":"2018-05-26T15:32:57.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/11316/matplotlib/issues/11316"}