View Issue Details
|ID||Project||Category||View Status||Date Submitted||Last Update|
|0015957||Scribus||Color Management||public||2019-11-19 14:23||2020-03-08 22:33|
|Target Version||Fixed in Version||1.5.6.svn|
|Summary||0015957: Embedded ICC color profiles of PNG images are not detected during import|
|Description||The embedded ICC color profile of an imported raster image is not detected.|
I'm attaching the Png that was contained in the .sla uploaded by derAndere1 on Github:
The issue on Github contains a few more details.
|Tags||No tags attached.|
original.PNG (1,685,088 bytes)
||PNG files are read by using Qt image reading functions which do not allow us to retrieve any embedded ICC profile. The only formats where we support retrieving embedded ICC profiles are JPEG, TIFF and PSD.|
||mmm... since PNGs are more and more used for serious work, would it be possible to use a "real" png library for reading them?|
Yup, but not right now. I would rather see an intermediate solution where we would continue to do as now for reading image data, but have specific function for extracting embedded profile from png using libpng.
Also one tip: I've noticed that the original image is a 16bit image using a linear RGB profile. We have no support for exporting 16bit images to PDF without converting them to 8bit and image color management is anyway performed on 8bit data. So importing an image with an embedded linear RGB profile is asking for trouble.
Hey! Just to let you know; I discovered I was affected by this bug too for my Pepper&Carrot "big collection" book project. (Funny to see the PNG reported uses also Pepper&Carrot picture, that's cool). I'll switch my project to another input format to try to workaround.
I have no idea how color convertion behaves without a source profile to target the CMYK profile of my printer in this context and if it can explain the bad color I'm getting once printed so far.
||I did some tests with the new colorspace related functionalities in Qt 5.14. Unfortunately at this point it seems that the ICC profiles one can retrieve using these new functionalities are not consistent with the image data leading usually to excessively bright images. In fact during the tests I did, I got the expected result in a single case. In the case of the image attached to this issue, Qt could even not return the correct profile data. So at this point it seems these new Qt 5.14 functionalities are unusable.|
So in the end I used libpng directly so as to get the embedded icc profile. So now Scribus has a new direct dependency on libpng.
In order to get embedded profiles from PNGs when loading old documents, it will be necessary to reload images by clearing content first (Right click on item > Content > Clear) then import image again as usual.
|2019-11-19 14:23||ale||New Issue|
|2019-11-19 14:23||ale||File Added: original.PNG|
|2019-11-19 14:25||ale||Description Updated||View Revisions|
|2019-11-19 15:20||jghali||Note Added: 0047107|
|2019-11-19 15:21||jghali||Summary||embedded ICC color profiles of raster images are not detected during import => Embedded ICC color profiles of PNG images are not detected during import|
|2019-11-20 07:47||ale||Note Added: 0047108|
|2019-11-20 08:08||jghali||Note Added: 0047109|
|2019-12-16 17:43||davidrevoy||Note Added: 0047276|
|2020-03-05 10:33||jghali||Note Added: 0047429|
|2020-03-08 22:33||jghali||Assigned To||=> jghali|
|2020-03-08 22:33||jghali||Status||new => resolved|
|2020-03-08 22:33||jghali||Resolution||open => fixed|
|2020-03-08 22:33||jghali||Fixed in Version||=> 1.5.6.svn|
|2020-03-08 22:33||jghali||Note Added: 0047432|