René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"Saving a pdf, with a single image, grayscale colormap, and transparent background produces a black background","articleBody":"This issue appears to be similar to what eventually got resolved in https://github.com/matplotlib/matplotlib/pull/1894\n\nIf I save a pdf with a single image, grayscale colormap and a transparent background, the axes background does not remain transparent.  It becomes a black background.  If I deviate from any of those ingredients, then the background is transparent as specified.\n\nExample:\n\n```\nimport matplotlib.pyplot as plt\nfrom numpy.random import rand\n\nfig, ax = plt.subplots(nrows=3, ncols=1, sharex=True)\n\nax[0].imshow(rand(15,15), extent=[0, 2, 15, 0], \\\n            cmap=plt.cm.gray, aspect='auto', interpolation='Nearest')\n\nax[1].imshow(rand(15,15), extent=[0, 2, 15, 0], \\\n            cmap=plt.cm.rainbow, aspect='auto', interpolation='Nearest')\n\nax[2].imshow(rand(15,15), extent=[0, 2, 15, 0], \\\n            cmap=plt.cm.gray, aspect='auto', interpolation='Nearest')\nax[2].imshow(rand(15,15), extent=[4, 6, 15, 0], \\\n            cmap=plt.cm.gray, aspect='auto', interpolation='Nearest')\n\nax[-1].set_xlim([0, 8])\nfig.savefig('transparent.pdf', format='PDF', transparent = True)\nfig.savefig('opaque.pdf', format='PDF', transparent = False)\nfig.savefig('transparent.png', format='PNG', transparent = True)\n```\n\nHere is 'transparent.pdf', with the black background on the first set of axes:\n![transparent-pdf](https://cloud.githubusercontent.com/assets/4099759/6770161/e5545712-d07d-11e4-9bb1-05bf047a87ba.png)\n\nHere is 'opaque.pdf', which looks correct:\n![opaque-pdf](https://cloud.githubusercontent.com/assets/4099759/6770166/022ea176-d07e-11e4-9f17-eeb629fbdfed.png)\n\nHere is 'transparent.png', which also looks correct:\n![transparent](https://cloud.githubusercontent.com/assets/4099759/6770171/17c3a932-d07e-11e4-9efc-fcbc581d1a95.png)\n\nIn case it matters, I am on Mac OS X 10.8.5, Enthought Canopy Python 2.7.6, and Matplotlib 1.4.0\n","author":{"url":"https://github.com/breedlun","@type":"Person","name":"breedlun"},"datePublished":"2015-03-22T16:28:58.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/4260/matplotlib/issues/4260"}