I wrote a lot of the Skia color management code involved here, and I think maybe I can clear some things up? I'd be happy to answer any questions you might hav

I wrote a lot of the Skia color management code involved here, and I think maybe I can clear some things up? I'd be happy to answer any questions you might have, either here or on https://bugs.chromium.org/p/skia/issues/detail?id=10301 https://bugs.chromium.org/p/skia/issues/detail?id=10301 where we've been trying to think about how much Skia's involved with the root cause of this bug. There's no "Skia color profile" per se. When Skia's asked to write a JPEG from a pixel buffer tagged with a color profile (SkColorSpace), we auto-generate an ICC profile programatically from the parameters that describe the color gamut and transfer functions we use to represent those color profiles. That's what the code in this file is up to: https://source.chromium.org/chromium/chromium/src/+/master:third_party/skia/src/core/SkICC.cpp https://source.chromium.org/chromium/chromium/src/+/master:t... So this profile is one of infinite possible profiles that'll have "Google/Skia/..big long MD5.." somewhere in them. This profile in particular looks like it's probably describing the ProPhoto color space, which is very, very large and uses imaginary colors outside visible light to increase its gamut. While the JPEG itself is always storing values in range in the ProPhoto gamut, when you convert that to another gamut (say, to match the display, or to sRGB) it's very easy to end up with logical color channel values less than zero or greater than one, which do make a kind of sense, but not to code that expects colors are always sRGB bytes. It's unclear to me what gamut the colors being read in that Java code are in, and that'd very much affect what the appropriate values for that LUMINOSITY_MATRIX should be. Those are the correct values to get the luminosity for sRGB colors (though I think what's being calculated here is subtly-different gamma-encoded "luma" instead), but they're not likely a sound way to get luminosity if the image is in any different gamut. A typical strategy is to convert any image you load to the display gamut early, since you'll need to do that eventually to display it. And it's more and more common that phone display gamuts are not sRGB, usually something wider now like Display P3.