View Full Version : opening linear 32 bit HDRI files in Photoshop

04-16-2010, 02:40 PM
I recently built an HDRI file in photoshop using Automate > merge to HDR. When I reopen the file in Photoshop, Photoshop forces me to assign a color profile to the file. The default choice is Linear sRGB. When I assign this profile the file opens and looks much brighter than when I made it... it seemed to be displayed as "linear", darker, in Photoshop before I originally saved it.

Will re-saving this file now change the way this file behaves, in a rendering program for instance.

Can anyone explain what is going on?

Thanks for reading!

04-16-2010, 04:19 PM
linear RGB is an uncorrected (linear) gamma and is the best way to store HDR images - to get it to look normal, you have to apply a gamma to it. Add an Exposure adjustment and change the gamma to .45 (the inverse of sRGB's gamma 2.2). Then it will show up properly.

04-17-2010, 03:51 AM
Right, perhaps my question should be, can anyone explain the Linear sRGB IEC61966-2.1 (D65) profile? Seems like it views as sRGB in Photoshop, but preserves the linear uncorrected data, as the file seems to perform exactly the same after saved with this profile.

04-20-2010, 02:33 PM
well sRGB is usually 2.2 gamma so the linear sRGB would just sRGB's working colour space with a linear gamma.

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04-20-2010, 02:33 PM
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