[dfbrown]

I'm not an expert in the topic, but my understanding is RGB is a poor color space for computing color difference. This could be why your mosaics end up so washed out. [1] suggests using a CIELAB color space [2].

Edit: Looking at the code more closely it looks like you were using Lab at one point but commented it out[3], so I'm guessing you're already aware of this.

1: https://stackoverflow.com/a/9019461/185171

2: https://en.wikipedia.org/wiki/CIELAB_color_space#CIELAB

3: https://github.com/worldveil/photomosaic/blob/bb720efda11383...

[muzakthings]

It didn’t make a ton of difference empirically when I tried it.

But you’re correct, generally that’s the space you want to be in.

[gedy]

It is quite noticeable when you are using a limited selection of tiles or image has desaturated colors.

I've done some similar work[1], but issue with L*ab color is it's terrifically slow to calculate diff, at least in JS.

[1] https://imgur.com/a/g3EzcSV

[itronitron]

there is no perfect way to measure color distances, mostly because it needs to account for human perception of color and there are individual differences in color perception among people.