[Development] Color Profile support on Qt

alessandro.portale at nokia.com alessandro.portale at nokia.com
Mon Jul 16 17:42:45 CEST 2012


(Sorry for top-posting, as-well)

Great to see Qt soon supporting color profiles! I agree with Johan that color profile handling and conversion should be an opt-in feature.

Just a few questions:
1) Would Qt use (and ship) a color conversion library, or would the system library be used where available (e.g. on OSX and Windows)?
2) Would the screen color profiles that are specified in the system screen settings automatically be used?
3) Sometimes, there are different profiles defined -one per screen (and printer)-. Would we have an additional parameter to specify the screen id?

I hope not to complicate things with my questions :)
________________________________________
From: development-bounces+alessandro.portale=nokia.com at qt-project.org [development-bounces+alessandro.portale=nokia.com at qt-project.org] on behalf of Dermenakis Alexandros (Nokia-MP/Oslo)
Subject: [Development] Color Profile support on Qt

Hi,

I am working on adding support for color profiles on Qt 5. It is under discussion if the default behavior of QImage shall be:

1) converting from an embedded color profile to the screen color profile when loading an image
OR
2) keep the loaded image in the source color space, until the programmer explicitly requests color conversion.

Solution 1 : QImage(xxxx, QColorProfile = Preserve_Embedded)
* Keeps the old Qt behavior (providing backwards compatibility without the need of tweaking the code)

Solution 2 : QImage(xxxx, QColorProfile = Convert_To_Screen)
* Fixes some "bugs" in applications that use QImage directly for visualizing images (i.e. okular)
* Better for newly developed applications since color profile conversion takes place automatically
Presently when an image is loaded it always gets interpreted as sRGB and no color conversion takes place.

Thanks in advance!

________________________________________
From: development-bounces+alessandro.portale=nokia.com at qt-project.org [development-bounces+alessandro.portale=nokia.com at qt-project.org] on behalf of ext e8johan at gmail.com [e8johan at gmail.com]
Sent: Monday, July 16, 2012 17:03
To: development at qt-project.org; Dermenakis Alexandros (Nokia-MP/Oslo)
Subject: Re: [Development] Color Profile support on Qt

Sorry for top posting.

Be aware that all usages of QImage goes not target the local screen. I.e. explicitly requesting a conversion seems to be the best option to me.

Regards,

Johan
On 2012-07-16 16:31 alexandros.dermenakis at nokia.com wrote:
Hi,

I am working on adding support for color profiles on Qt 5. It is under discussion if the default behavior of QImage shall be:

1) converting from an embedded color profile to the screen color profile when loading an image
OR
2) keep the loaded image in the source color space, until the programmer explicitly requests color conversion.

Solution 1 : QImage(xxxx, QColorProfile = Preserve_Embedded)
* Keeps the old Qt behavior (providing backwards compatibility without the need of tweaking the code)

Solution 2 : QImage(xxxx, QColorProfile = Convert_To_Screen)
* Fixes some "bugs" in applications that use QImage directly for visualizing images (i.e. okular)
* Better for newly developed applications since color profile conversion takes place automatically
Presently when an image is loaded it always gets interpreted as sRGB and no color conversion takes place.

Thanks in advance!

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