[Digikam-devel] [Bug 160438] New: Wish: Easy way to transform an image from one colorspace and bit-depth to another, like Krita's "Convert Image Type"

[Ar]

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http://bugs.kde.org/show_bug.cgi?id=160438         
           Summary: Wish: Easy way to transform an image from one colorspace
                    and bit-depth to another, like Krita's "Convert Image
                    Type"
           Product: showfoto
           Version: unspecified
          Platform: Ubuntu Packages
        OS/Version: Linux
            Status: UNCONFIRMED
          Severity: wishlist
          Priority: NOR
         Component: general
        AssignedTo: digikam-devel kde org
        ReportedBy: ari.reads gmail com


Version:           0.7.0 (the one that comes with Ubuntu Hardy 8.04) (using KDE 3.5.9)
Installed from:    Ubuntu Packages
OS:                Linux

I've been using showfoto as my main photo editor for two years now and I love all new GUI tweaks and new features in the latest stable release, 0.7.0 that comes with ubuntu 8.04. 

Now there is one long standing problem that is still lurking in the dark. I'll describe my workflow so that it is properly understood.

I shoot NEF, and then use UFRAW to convert to PNG, 16bits, WideGamut, and do wavelet de-noise.

Then I use Showfoto to crop and rotate, further adjust exposure / gamma / saturation, downsample (for web publication), sharpen. All this is done in 16-bit PNG with color-managed view, with widegamut as working space, and all works just fine.

Then in the last step (again, when working towards web publication), I need convert the image back to 8-bit RGB and save as JPG. 

Currently if I attempt to do this in Showfoto/digikam, I can go to Colors > Color Management > Work space profile: then I have to click on the file selection icon, select my sRGB icm file, and after that the colors in my image are not properly "mapped/transformed" from my current profile (widegamut) to my new one (sRGB). I am not sure exactly what showfoto is doing, but after I select the sRGB profile I see all the colors get extremely saturated and the transformation problem is obvious. Even if it worked, the whole process is very tedious.


What I end up doing is, after editing the image with showfoto, I save it as 16-bit PNG/WideGamut without attempting to change the color space or bit depth. Then I load it in Krita, which correctly gives me a color managed view by default (the PNG saved by Showfoto has the widegamut profile embedded), where I select Image > Convert Image Type > RGB 8-bit per channel. This transformation does not produce any visible alteration in the colors (like the one showfoto/digikam is producing), which makes sense when viewed in an LCD panel. And finally I save as JPG in Krita. 

My wish is to have showfoto/digikam offer an easy and simple way to transform the current image to a desired bit-depth and colorspace, offering some pre-defined common options (8 bits, 16 bits, sRGB, CMYK, like Krita) accessible from a "Target formats" list; and for other non-common situations, the option to select a custom .icm file (which could be a "Browse for .icm file ..." option in the "Target formats" list.


The current "Colors > Color Management > Work space profile" is too much for what I need to do and is not helping me do this common, simple transformation. 


Thanks for paying attention to this and for keeping digikam/showfoto up!