Soeren Sandmann wrote: > Simon Thum <[email protected]> writes: > >> For the more artistic cases directed at perceptual qualities (like >> some gradients, but not the WM shadow gradient!), luma modulation is >> of course desirable. But there are better tools for this purpose, like >> the L*a*b* space. So why go to such great lengths with luma mod? > > Compositing in sRGB is hardly going to great lengths. All I'm saying > is that compositing in linear RGB it not always the right choice. Me too, I was trying to say an additional channel is 'going to great lenghts'.
> can work out a formula that looks something like this: > > (m * s ** 2.2 + (1 - m) d ** 2.2) ** 1/2.2 + (1 - s_a * m) * d > > With current pixman you get the right color, but wrong antialiasing - > if you treated alpha as coverage, you'd get the wrong color, but the > right default. I don't think this can be broken into a simple property > on the operation; you really need an indication what the alpha channel > actually means. Ok, got it. Nice idea, it just wasn't apparent to me from the docs. However I wouldn't restrict that to luma modulation; newer SVG drafts enable also Lab and Lch to be specified for color interpolation. > I don't see how L*a*b bails you out either, because it > doesn't deal with translucency/coverage at all. Right, It's just better at reflecting properties of the visual system than plain RGB. Personally, I would use either linear RGB or Lab/Lch for colour interpolation, not encoded RGB. It's convenient, but 'between the chairs'. Cheers, Simon _______________________________________________ xorg-devel mailing list [email protected] http://lists.x.org/mailman/listinfo/xorg-devel
