René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[Bug]: Plotting numpy.array of dtype float32 with pyplot.imshow and specified colors.LogNorm produces wrong colors","articleBody":"### Bug summary\n\nPlotting an equal numpy.array of dtype float64 and float32 with pyplot.imshow and a defined colors.LogNorm as norm will produce different colors in the resulting image.\n\n### Code for reproduction\n\n```Python\nimport matplotlib.pyplot as plt\r\nimport matplotlib.colors as colors\r\nimport numpy as np\r\n\r\nnorm = colors.LogNorm(vmin=1e-10, vmax=1)\r\ntest_numpy = np.array([[1e-4]])\r\ntest_numpy_32 = np.array([[1e-4]], dtype=np.float32)\r\n\r\nfor test in [test_numpy, test_numpy_32]:\r\n    plt.imshow(test, norm=norm)\r\n    plt.title(f\"numpy array of dtype: {test.dtype}\")\r\n    plt.colorbar()\r\n    plt.show()\n```\n\n\n### Actual outcome\n\nThe resulting plot for the dtype float64 numpy.array looks like this:\r\n\r\n![float64](https://github.com/user-attachments/assets/64b75fc1-9a6f-4c35-8340-c285f26d0cd6)\r\n\r\nand the plot for the dtype float32 numpy.array looks like this:\r\n\r\n![float32](https://github.com/user-attachments/assets/dd53c1ab-95a5-453c-9a40-9a48e3f2bb85)\n\n### Expected outcome\n\nI would expect both outputs to have the same color.\n\n### Additional information\n\n_No response_\n\n### Operating system\n\nArch\n\n### Matplotlib Version\n\n3.9.1.post1\n\n### Matplotlib Backend\n\nmodule://matplotlib_inline.backend_inline\n\n### Python version\n\nPython 3.12.4\n\n### Jupyter version\n\n_No response_\n\n### Installation\n\npip","author":{"url":"https://github.com/faressc","@type":"Person","name":"faressc"},"datePublished":"2024-08-15T16:59:21.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":7},"url":"https://github.com/28731/matplotlib/issues/28731"}