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IIRC it is a late addition and only added because of people wanting some kind of color space guarantee. I don't think it was ever accurately specified what they

IIRC it is a late addition and only added because of people wanting some kind of color space guarantee. I don't think it was ever accurately specified what they do mean---presumably both share the sRGB color gamut and only differ by transfer functions, but it's a frequent misconception [1] that transfer functions can be parametrized with a single value, gamma, so I guess that's where the "linear" came from (implying gamma = 1.0). [1] The sRGB EOTF has a nominal gamma of 2.2 but it is actually a piecewise function with gamma varying from 1.0 to 2.4.

esperent 4y ago
> I guess that's where the "linear" came from (implying gamma = 1.0). "Linear" means the colors are stored in a state that means you can do linear transformations on them (basic math in other words) without loss. You can't do this with gamma corrected colors - for example as you say, the sRGB EOTF is a piecewise function so by definition it's not a linear transformation. So yes, when talking about "linear" colors, they still come from some gamut like sRGB or a larger HDR gamut. The linear part means they are safe for use in a renderer's internals.
andreareina 4y ago
I've implemented color-managed workflows so I should have suspected that of course sRGB would be like that, it has to.
- lifthrasiir 4y ago
  Yeah, if you have the slightest experience with color space you would know that's a misconception, but I've seen enough cases where the 2.2 gamma is uniformly applied throughout the brightness curve...
mananaysiempre 4y ago
Compare how Netpbm declared[1] that colour images are BT.709 (HDTV) relatively late in its existence, and seemingly every other implementation ignores that and treats them as sRGB (same—or close enough—primaries, different transfer function). [1] https://netpbm.sourceforge.net/doc/ppm.html https://netpbm.sourceforge.net/doc/ppm.html

esperent 4y ago

> I guess that's where the "linear" came from (implying gamma = 1.0). "Linear" means the colors are stored in a state that means you can do linear transformations on them (basic math in other words) without loss. You can't do this with gamma corrected colors - for example as you say, the sRGB EOTF is a piecewise function so by definition it's not a linear transformation. So yes, when talking about "linear" colors, they still come from some gamut like sRGB or a larger HDR gamut. The linear part means they are safe for use in a renderer's internals.

andreareina 4y ago

I've implemented color-managed workflows so I should have suspected that of course sRGB would be like that, it has to.

lifthrasiir 4y ago
Yeah, if you have the slightest experience with color space you would know that's a misconception, but I've seen enough cases where the 2.2 gamma is uniformly applied throughout the brightness curve...

mananaysiempre 4y ago

Compare how Netpbm declared[1] that colour images are BT.709 (HDTV) relatively late in its existence, and seemingly every other implementation ignores that and treats them as sRGB (same—or close enough—primaries, different transfer function). [1] https://netpbm.sourceforge.net/doc/ppm.html https://netpbm.sourceforge.net/doc/ppm.html