Image processing using indexed colors profiles

Feature requests
1

In order to achieve light web pages, it’s good to use images with indexed color profiles AND small pixel size. The problem is that the resize_image function looses the color index of the original image, leading to an image heavier than the original. See this example:

duniter-logo ae63c8b0dfd9c51a00 ae63c8b0dfd9c51a00_

Image 1 is 250x250 pixels and weights 14.8 kB
Image 2 is produced with resize image, is 160x160 pixels and weights 27.4 kB
Image 3 is created using GIMP’s color index applied on image 2 and is 160x160 pixels and weights 5.1 kB

We can see here that:

  1. the resized image is 1.8x heavier than the original despite having 2.4x less pixels
  2. we can produce a same-sized image 5.4x lighter using indexed color profiles

@keats, a quick fix in mind?

PS: for people who do not know indexed color profiles, see https://docs.gimp.org/en/gimp-image-convert-indexed.html

1 Like
2

Hmm we do use the image crate, I would need to check their docs to see if we’re doing something wrong.

1 Like
3

It seems not to be supported yet : https://github.com/image-rs/image/issues/389