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[Digikam-devel] [Bug 139657] New: Blueish tint in low saturation images converted to CMYK

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Ari

[Digikam-devel] [Bug 139657] New: Blueish tint in low saturation images converted to CMYK

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http://bugs.kde.org/show_bug.cgi?id=139657
Summary: Blueish tint in low saturation images converted to CMYK
Product: digikam
Version: 0.9.0
Platform: Ubuntu Packages
OS/Version: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: Image Editor
AssignedTo: digikam-devel kde org
ReportedBy: ari.reads gmail com

Version: 0.9.0 (using KDE KDE 3.5.5)
Installed from: Ubuntu Packages
OS: Linux

This is with Digikam 0.9.0 final.

This is the scenario: I start with an sRGB JPEG image with very low saturation (looks nearly B&W). Open it in image editor, then save it as is as TIFF (8 bits, no compression).

Open the tiff in Krita or in Photoshop. Convert to CMYK. Voila, looks blueish.

Now: open the original JPEG directly with Krita (or photoshop). Save as tiff (RGB, 8 bits, no compression). Now reopen the tiff in Krita/PS and convert it to CMYK. Voila, looks nice, no blueish tint.

I run into this issue the hard way, after carefully preparing my images and then importing them to my Lab's print order management application, that does some 'softproofing' that actually smells and behaves like CMYK conversion. All my carefully digikam-processed images were blueish!!

With Nikon D80-generated sRGB JPGs, Krita tiffs, Photoshop tiffs, look nice in this app. Digikam tiffs look blueish, totally different from what digikam shows. Maybe a color-profile-related problem?

My workaround is: generate the tiffs with Krita, then continue the workflow on digikam. Seems to work fine (will confirm when the prints are delivered...)

Will attach the original jpg, and two tiffs, one generated with digikam's image editor and the other with krita. All default options. (I played in krita removing alpha channel, changing color space, etc, it always works OK (images never turn blue)).
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Ari

[Digikam-devel] [Bug 139657] Blueish tint in low saturation images converted to CMYK

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http://bugs.kde.org/show_bug.cgi?id=139657

------- Additional Comments From ari.reads gmail com 2007-01-06 02:24 -------
The test images can be found here:

http://www.arielpablo.com.ar/unprotected-files/

The original photo is jpg and can be found there.
The two created tiffs were 40Megs each, I downsampled them both with Digikam. Same behavior can be observed in the downsampled image.

In Krita, doing Image > Convert Image Type > CMYK (8 bits etc, all default options).

The tiff created by krita still looks OK after the conversion. The tiff created by digikam turns bluish.
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Bugzilla from hugelmopf@web.de

[Digikam-devel] [Bug 139657] Blueish tint in low saturation images converted to CMYK

In reply to this post by Ari

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http://bugs.kde.org/show_bug.cgi?id=139657

------- Additional Comments From hugelmopf web de 2007-01-20 14:40 -------
I can confirm this in digikam compiled from trunk r625297.

The debug output from opening the file in the editor until saving it as tiff is the following:

digikam: Found JPEGLossless plugin
QFile::open: No file name specified
QFile::open: No file name specified
digikam: /home/newuser/Pictures/test/dsc_0006.jpg : JPEG file identified
digikam: Exif color-space tag is sRGB. Using default sRGB ICC profile.
digikam: Exif Orientation: 1
digikam: mimetypes=image/x-portable-bitmap image/x-pcx image/x-portable-greymap image/x-xbm image/x-targa image/png image/x-portable-pixmap image/jpeg image/x-xpm image/x-eps image/x-bmp image/jp2 image/x-rgb image/tiff
digikam: Saving to :/home/newuser/Pictures/test/NR22oa.digikamtempfile.tmp (tiff)
digikam: (401x600) JPEG image preview size: 45784 bytes
digikam: Dirty: /test
kio_digikamalbums: [static Digikam::DImg::FORMAT Digikam::DImg::fileFormat(const QString&)] Failed to read header of file "/home/newuser/Pictures/test/NR22oa.digikamtempfile.tmp"
digikam: Dirty: /
digikam: renaming to /home/newuser/Pictures/test/dsc_0006.tiff
digikam: ImageInfo::copyItem 1 dsc_0006.jpg to 1 dsc_0006.tiff
digikam: Dirty: /
digikam: Dirty: /test
digikam: Dirty: /
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Bugzilla from hugelmopf@web.de

[Digikam-devel] [Bug 139657] Blueish tint in low saturation images converted to CMYK

In reply to this post by Ari

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http://bugs.kde.org/show_bug.cgi?id=139657
hugelmopf web de changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|UNCONFIRMED |NEW
everconfirmed|0 |1
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Gilles Caulier-4

[Bug 139657] Blueish tint in low saturation images converted to CMYK

In reply to this post by Ari

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http://bugs.kde.org/show_bug.cgi?id=139657

------- Additional Comments From caulier.gilles gmail com 2008-03-18 13:52 -------
Ar, Frank,

This entry still valid with 0.9.3 release or current implementation from svn ?

Gilles Caulier
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Ari

[Bug 139657] Blueish tint in low saturation images converted to CMYK

In reply to this post by Ari

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http://bugs.kde.org/show_bug.cgi?id=139657

------- Additional Comments From ari.reads gmail com 2008-03-19 00:11 -------
The problem seems to be fixed in 0.9.3

Thanks
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Gilles Caulier-4

[Bug 139657] Blueish tint in low saturation images converted to CMYK

In reply to this post by Ari

------- You are receiving this mail because: -------
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http://bugs.kde.org/show_bug.cgi?id=139657
caulier.gilles gmail com changed:

What |Removed |Added
----------------------------------------------------------------------------
Status|NEW |RESOLVED
Resolution| |FIXED

------- Additional Comments From caulier.gilles gmail com 2008-03-19 06:13 -------
Ok, thanks for the report.

I close this file now.

Gilles Caulier
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