hi bagginsbill,

thanks for comment. As I stated in my first post in this thread, you're always right (well, about) and I miss something (well, not always).

JPG indeed can have a profile like sRGB or AdobeRGB embedded, which then is used for the colormapping for exactly the reason you explained: otherwise we would have not enough detail in the low and high ends. But... actually most JPGs do not have a profile embedded at all. In that case, a gamma 2.2 is used (and before Snow Leopard 2009, Mac used 1.8 instead). The difference between sRGB and gamma 2.2 is limited, but nevertheless. In any case, there is no linear colordata in JPG. Actually, there is no real RGB in JPG either, it's more Photoshop Lab alike.

Other file formats, like BMP (and TIFF? PNG? AVI) do not have any colormapping included and hence contain linear RGB-like colordata, while MPG (as on DVD's) has gamma=2.2 embedded.

(It's all on the Wikipedia pages you were quoting from, on JPEG, Gamma and more).

So, PP2010 uses the sRGB profile instead of gamma 2.2, when sRGB is included. What if another profile is included? What if no profile is included? What if the texture is in non-JPG format? Can GC (a gamma value) be set on a per-texture basis or is it an overall setting? Just asking.

Gamma Correction is a generic action on images which can be performed in Photoshop, it exactly does as I said. When using Levels, the middle number denotes the gamma correction, and a value of 2 brightens a 50% gray to 71%. Using curves, raising the midpoint (127,127) to (127,180) does exactly the same. As can be seen, a small range in the dark is mapped onto a large range, enabling to view more detail. 

sRGB includes (an close approach to) gamma, but essentially it's a color definition which tells us which shade is meant by extreme red, as in (255,0,0) or any equivalent. Extreme red in sRGB is different from extreme red in AdobeRGB, or RAL, or LAB, or Pantone, or whatever colorspace you're referring to. Such is relevant when you've got to produce the same color on various media, like plastic, wood-paint, textile, paper and so on.

So, whether one needs gamma or sRGB to get more detail out of the dark, is more a case of semantics to me. One can do gamma correction without sRGB, but when one maps onto sRGB, the gamma is included.

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Usually I'm wrong. But to be effective and efficient, I don't need to be correct or accurate.

visit www.aRtBeeWeb.nl (works) or Missing Manuals (tutorials & reviews) - both need an update though