Re: [Openexr-devel] OpenEXR files with nonlinearly encoded RGB

[Elle Stone]

On 02/23/2015 12:08 PM, Bob Friesenhahn wrote:
> Most "free/libre editing applications" do not natively use floating
> point to store internal raster data and they display their data using
> interfaces which only support 8 integer bits per sample.  OpenEXR is
> useful to store floating point data.  The whole path may not be loss
> free unless it is round-tripped in the same format.

At one point, and with the notable exceptions of Cinepaint and some of 
the command-line-only programs, free/libre image editors mostly worked 
with 8-bit data.

Things have changed. RawTherapee and darktable do all internal 
processing at 32f. Darktable allows saving to disk 32f OpenEXR and tiff. 
RawTherapee hasn't yet added support for outputting 32f images, but it's 
being worked on.

GIMP 2.8 only works with 8-bit images internally. But GIMP 2.9 from git 
has worked with 32-bit images for several years now, does all processing 
at 32f, and provides input-output options for several high bit depth 
file formats.

Krita, of course, has supported 32f images for a long time.

> However, floating point TIFF and ICC do not normally go hand in hand.

I'm confused by this statement. LCMS reads and writes ICC profiles 
embedded in floating point tiffs. GIMP 2.9 exports 32f tiffs with 
embedded ICC profiles and darktable recognizes the embedded ICC 
profiles, and vice versa. And so on. And so forth.

Elle