I was experimenting with colors, trying to create a film-like look with non-linear output relative to the input, but I realised it isn’t quite possible. The Channel Mixer in the color tab is basically a 3x3 matrix, which is rather powerful but linear. And even if the RGB Curves let you create non-linear response to input (hence the “curves”), it only goes from red to red, green to green and blue to blue. It doesn’t let you mix the color channels.
So my idea is basically an extension to the RGB Curves, some kind of advanced mode, where you have 3x3 curves to play with. For each output color channel, you have three curves (one per input color channel, RGB). That way, you should in theory be able to create your own “film” if you like. Wouldn’t that be extremely powerful?
Like I wrote, the RGB Curves are limited since there’s only one curve per channel. What I’m interested in is something like the Channel Mixer with curves instead of fixed values. Not that I need it, but it would be very powerful and fun to experiment with. I believe that tool alone would be able to replace all kinds of “hacks” people use to get that film look.