[akrasuski1]

Hmm, I guess someone would have thought of that, but this could probably be used for compressing images by reorienting the color axes so that one of them is perpendicular to this color plane, and then sending less information about that coordinate.

[abainbridge]

Yeah, you can use principle component analysis to figure out the transform to make the colour space "optimal" for compression of a specific image. I tried that once:

https://bainbridgecode.wordpress.com/2012/04/24/beating-png-...

and

https://bainbridgecode.wordpress.com/2012/05/07/beating-png-...

There are plots at the end of part 3 showing the image channels separately for YCrCb and my custom PCA derived space. They clearly show that there's a lot less duplication of data between channels with the latter. And that in turn is obviously good for compression.

[thomasahle]

Finding the first primary component also appears to be a pretty good way greyscale an image.

[iainmerrick]

https://en.wikipedia.org/wiki/YUV