René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"RGBA values produce different result for imshow and for markers","articleBody":"In the following example, I produce 9 colors ranging from completely transparent red to completely opaque red. In the case of imshow, the lighter colors actually end up being closer to gray, whereas for the scatter markers, the colors look as one would expect. What could be causing this?\n\n``` python\nimport numpy as np\nimport matplotlib.pyplot as plt\n\ndata = np.arange(9, dtype=float).reshape((3, 3)) / 8.\n\ncolor = np.array([1, 0, 0, 1], dtype=float)\n\narray = color * np.ones(data.shape + (4,))\narray[:, :, 3] *= data\n\nfig = plt.figure()\nax = fig.add_subplot(1, 1, 1)\nax.imshow(array, vmin=0, vmax=1, interpolation='nearest')\nfor i in range(3):\n    for j in range(3):\n        ax.scatter(i, j, s=500, facecolor='white', edgecolor='white', alpha=1.0)\n        ax.scatter(i, j, s=400, facecolor=array[j, i], edgecolor='white')\nfig.savefig('colors.png')\n```\n\n![colors](https://cloud.githubusercontent.com/assets/314716/18963537/4f59c48e-866d-11e6-8c60-d66aeb1d0cdd.png)\n","author":{"url":"https://github.com/astrofrog","@type":"Person","name":"astrofrog"},"datePublished":"2016-09-29T16:51:16.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":3},"url":"https://github.com/7201/matplotlib/issues/7201"}