[Development] Color Management support in Qt 5?

Chris Gilbert cgilbert at knaldtech.com
Sun Nov 10 00:04:37 CET 2013

We created our own platform agnostic image loading and management code 
outside of Qt due to lack proper support in QImage for non typical texel 
formats/bit depths.

(We support 8bit/16bit/32bit int and 16bit/32bit floating point)

It should also be mentioned that on top of the QImage[Reader] code 
supporting load for these "exotic" texel types, it's also important to 
ensure that any kind of texel transformation documents which texel 
formats it is able to operate in. (eg: if the transformation happens in 
8bit int only it will degrade your 16 bit half float texel data during 
down-conversion for transformation)

This is actually a surprisingly common "under the hood" issue with these 
kinds of less texel types even in applications such as Adobe Photoshop. 
(A good way to test is with a large (4k, 8k, etc) test input texture 
with a unique value for each texel - it's easy to detect after a 
load/save or non-destructive xform if you have reduced the number of 
unique values and to what degree)

I'd be open to helping out with this in QImage if the feature is a 
serious candidate for inclusion into Qt. I'd also very much like to see 
optional support for the kind of formats that support this type of texel 
data well, such as OpenEXR.

Chris Gilbert
Knald Technologies, LLC

On 11/9/2013 5:03 AM, Christoph Feck wrote:
> On Saturday 09 November 2013 12:50:24 Olivier Goffart wrote:
>> I think milestones could rather be:
>> 1) QImage[Reader] converts automatically to linear color space, so
>> that all QImage's are in the linear color space
> Needs a 48 bit QImage. I remember a proposal to add support for larger
> bit depths was rejected, but cannot find the reference right now (to
> check how old the proposal was).
> Christoph Feck (kdepepo)
> KDE Quality Team
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