2007.10.23 07:09 "[Tiff] Floating-point 32bit sample data", by Nikita V. Borodikhin

2007.10.24 16:47 "Re: [Tiff] Floating-point 32bit sample data", by William B Thompson

On Tuesday 23 October 2007 01:09, Nikita V. Borodikhin wrote:

Are floating point RGB data stored gamma corrected or linearized? How should I use ICC workflow while processing data? ICC workflow is based on integer data, not float...

On Tuesday 23 October 2007 15:38, Chris Cox wrote: > HDR data _really_ needs to be gamma 1.0, and floating point image data is > best represented as gamma 1.0.

Photoshop CS3 appears to exhibit the following behavior with 32 bit(float)/channel images:

The "(Linear RGB Profile)" versions of the ICC profiles do not appear in Program Files\Common Files\Adobe\Color\Profiles in Windows XP, nor does the "XYZ Profile".

The document describing the Adobe RGB (1998) Color Image Encoding specifies that (0.0, 0.0, 0.0) should correspond to the color space back point and (1.0, 1.0, 1.0) should correspond to the color space white point. It further specifies that "Component values outside the range [0, 1] are not allowed for floating-point encodings."

Photoshop CS3 allows assigning profiles to 32 bit(float)/channel images, but does not support profile conversion (which would have the effect of rescaling the image). It reads and writes 32 bit(float)/channel TIFF images containing values outside this range without clipping.

        - Bill

William B. Thompson

Professor, School of Computing, University of Utah 50 So. Central Campus Dr., Rm 3190, Salt Lake City, UT 84112

thompson@cs.utah.edu, 801-585-3302 (ph), 801-581-5843 (fax) http://www.cs.utah.edu/~thompson