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Old March 2nd 14, 02:37 AM posted to sci.engr.color,sci.image.processing,rec.photo.darkroom,rec.photo.digital,comp.soft-sys.matlab
Dale[_4_]
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Posts: 131
Default dynamic range and exposure latitude?

On 03/01/2014 08:48 AM, Jeroen wrote:

Sounds good. Maybe you can give some thought on how a DCI P3
color gamut carried in a BT.2020 wide color gamut can be
automatically mapped back into a BT.709 (sRGB) color gamut ?
There will be a lot of need for that, because most UHD ("4k")
standards will be based on BT.2020 color primaries.


brings up a storage/portability issue, easily solved with ICC

keep a copy of the image in a device independent space with appropriate
RIMM, ERIMM,, ROMM applied like the profile connection space and then
"purpose" it again instead of "repurposing" a file in an ouput device space

you could also keep your edits on the file as ICC abstract profiles
along with the device independent file,, or just keep the edited file in
the working space

mapping gamut can be done the hard way (mechanistic) or the easy way
(empirical)

the easy way is too print a wide variety of machine code values to the
output devices, measure the color or spectral characteristics, and then
choose whether to convert it colorimetrically, absolute colorimetrically
or maintaing saturation (perceptual mapping involves PRM(G) which is a
print space, smaller than display/projection/editing for film or digital

ideally you create a gamut conversions to the profile connection space,
so they are device independent and can be "purposed" instead of "repurposed"

I don't recall the mathematics of gamut mapping, I wasn't that
experienced, but a three dimensional look up table could be used with
linear or high power polynomials

--
Dale