Sorry about all the delay. This thread started when I was on vacation, and then when I got home it was all about last minute preparation for SIGGRAPH, then SIGGRAPH itself, and so I was really short on time.
It looks to me that the artifacts are likely the result of the slightly negative lobes of the default Lanczos filter that resize() will use when downsizing. Sometimes this makes ringing artifacts in high-contrast regions. And it's a better choice when downsizing by a larger factor, because it sharpens a little. That may be good if you are downsizing by 2x or more, but if only slightly changing (128 to 100 in this example) it may not be the best choice. There is not necessarily any one "right" filter for all use cases -- it's a set of technical and aesthetic trade-offs that may vary according to the purpose, needs, and desired appearance. ImageBufAlgo.resize() lets you choose the filter by name. You may find blackman-harris more pleasing, but that's just a guess. I would try them all and see what works best for this particular purpose > On Aug 10, 2022, at 9:31 AM, Max Shooster <mshoos...@laika.com> wrote: > > Hello. Upon further inspection there also are artifacts present when using > the oiiotool's resize. For example, when using the sample multichannel exr > here > (https://github.com/Psyop/Cryptomatte/blob/master/sample_images/debug_images/multichannel.exr > > <https://github.com/Psyop/Cryptomatte/blob/master/sample_images/debug_images/multichannel.exr>). > And running oiiotool resize `oiiotool multichannel.exr --resize 100x100 -o > output.exr` there are visible artifacts present in the resized image. > > _______________________________________________ > Oiio-dev mailing list > Oiio-dev@lists.openimageio.org <mailto:Oiio-dev@lists.openimageio.org> > http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org > <http://lists.openimageio.org/listinfo.cgi/oiio-dev-openimageio.org> -- Larry Gritz l...@larrygritz.com
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