How create indexed image?

[BratSinot]

I found function "image::imageops::colorops::dither", what convert pixel colors, but image still RGB. "image::imageops::colorops::index_colors" return indexes, not image. So how create custom image with palette?

[nwin]

There is no generic interface yet to make use of these functions. But you can simply save the image as GIF (paletted PNG is not supported yet), that will reduce the image to 256 colors.

[Hugo-Trentesaux]

So there is no way of creating PNG with indexed color profile?

Example of use case: https://zola.discourse.group/t/image-processing-using-indexed-colors-profiles/499/3

[fintelia]

I believe that the PNG crate supports it now (see Encoder::set_palette), but there aren't plans to expose that functionality in this higher level crate.

[HeroicKatora]

I would recommend opening a new issue, for example to discuss a potential interface for this. For comparison gif is essentially always an indexed color profile and, as fintelia mentioned, png does support it so I wouldn't rule out adding support for it in some way. Posting on a closed issue from 5 years ago however will be limited in usefulness, a lot of things have changed and only maintainers and the original posters get notified.