[Lcms-user] bug(?): precision loss in floating point transforms

[Anders T. <to...@lu...>]

There seems to be a special case with linear gamma icc profiles which 
causes tonecurves to become 16 bit tables even for floating point math 
which leads to precision loss. In normal applications this is not 
detected as it is buried in deep shadows, but in HDR it is.

To me this seems to be a bug.

More detailed analysis can be found in this issue report for 
rawtherapee (which uses lcms2), which also includes a suggested bug 
fix by patching cmstypes.c:

http://code.google.com/p/rawtherapee/issues/detail?id=1642

(lots of discussion, read the last comments and up to get to the point 
immediately).

If there is a workaround that does not require patching lcms2 please 
let me know.

/Anders