Feature: map_linear_colors

[carrascomj]

This may be a bit too specific but I find it quite common. The idea is to have a function map_linear_colors(), similar to map_colors(), that operates on Images with Rgb/a pixels. For each pixel:

1. Remove gamma correction: Rgb<u8> [0,255] -> linear Rgb<f32> [0,1].
2. Apply user function: f(linear RGB) -> linear RGB.
3. Apply gamma correction: linear Rgb<f32> [0,1] -> Rgb<u8> [0,255].

(I think I got the naming right)

If is interesting for the library, I could do a PR for it.

[ripytide]

I think this libraries policy is to always assume linear color space due to implementation complexity/performance and we are otherwise color-space agnostic.

That said you could accomplish this pretty easily in user-land using:

let mut image = Image::new(..);
map_pixels_mut(image, |pixel| {
    let linear = to_linear(pixel);
    let mapped = f(linear);
    to_gamma(mapped)
});

So I'm not sure if this is a necessary function for the library.

[carrascomj]

Yes, with the perspective or time, I think that's fair, we can close this issue.