May be we have different understandings of “Linear”. In my opinion, sensor raw data is linear, but sRGB color space is non-linear(with sRGB gamma curve). Have a try with my DNG sample, if we set output profile as RT_sRGB, then save a png image, we get what is almost same with DNG looks like opened by RT. If we set output profile as RT_sRGB_g10, save a png, then we get linear image, as my uploaded png seems. Their difference is an sRGB gamma curve applied in RT_sRGB. Actually sRGB gamma curve is convex curve which make image more bright. I think RT_sRGB.icc Curve Tag is a description of output device curve, which means we have to apply a convex curve to compensate the concave curve. Otherwise we can’t explain why RT_sRGB.icm make image more bright than RT_sRGB_g10.icm.
We agree on all the above except
… it looks more bright because the PNG (additionally to what you mention), is wrongly treated as gamma encoded due to PNG’s incompatibility with icc data. If you export in icc compatible format (tiff/jpeg) both linear and gamma encoded will correctly be rendered equally bright …
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@Christian : I already brought your attention on the fact that you cannot use PNG format to render photos (unless you are aware that it is not color managed). It makes you take false conclusions. Use Tif or jpeg for photos and use PNG for icones or graphical art if you want.
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