René's URL Explorer Experiment

{"@context":"https://schema.org","@type":"DiscussionForumPosting","headline":"[ENH]: directional antialiasing filter","articleBody":"### Problem\n\nCurrently, the antialiasing filter used by imshow() is applied both in the x and the y direction.  There are cases where \"image-like\" data is highly sampled in one direction (requiring antialiasing) but not in the other, and also has some nans; an example is a kymograph like subfigure 1c at https://www.nature.com/articles/s41467-017-01462-y/figures/1\n\nFor such data, the current default interpolation settings (antialiased + rgba (because *one* of the directions is oversampled) can yield not nice artefacts, in particular at the boundary between \"data\" and \"nan\":\n\n```python\nfrom pylab import *\n\nvals = np.full((50, 500), np.nan)\nfor i, row in enumerate(vals):\n    n = 200 + np.random.randint(300)\n    row[:n] = np.sin(np.arange(n) / 10 + i / 5)  # make some fake data\naxs = figure(layout=\"constrained\", figsize=(10, 10)).subplots(\n    3, 3, subplot_kw={\"xticks\": [], \"yticks\": []})\nfor i, interpolation in enumerate([None, \"none\", \"antialiased\"]):\n    for j, stage in enumerate([None, \"data\", \"rgba\"]):\n        axs[i, j].text(0, 0, f\"{interpolation=}, {stage=}\", bbox={\"fc\": \"w\"})\n        axs[i, j].imshow(vals.T, aspect=\"auto\", origin=\"lower\",\n                         interpolation=interpolation, interpolation_stage=stage)\nshow()\n```\n![Image](https://github.com/user-attachments/assets/555481be-c62a-4d41-8d11-0971f565519d)\n\nFor this specific dataset, the best settings currently available is probably to go back to interpolation=\"data\".  But ideally, it would be nice if it was possible to have a separable antialiasing filter (I don't actually know if the current one is separable), so that one can apply it (here) only in the vertical direction (ideally in rgba space).\n\n### Proposed solution\n\n_No response_","author":{"url":"https://github.com/anntzer","@type":"Person","name":"anntzer"},"datePublished":"2025-03-06T11:49:33.000Z","interactionStatistic":{"@type":"InteractionCounter","interactionType":"https://schema.org/CommentAction","userInteractionCount":17},"url":"https://github.com/29711/matplotlib/issues/29711"}