https://bugs.kde.org/show_bug.cgi?id=424551
Bug ID: 424551
Summary: Gamma error in picture scaling
Product: krita
Version: 4.3.0-beta1
Platform: Other
OS: Linux
Status: REPORTED
Severity: major
Priority: NOR
Component: Filter Layers
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
Created attachment 130324
--> https://bugs.kde.org/attachment.cgi?id=130324&action=edit
Specially crafted image to demonstrate gamma error
SUMMARY
Resizing images produces a gamma error. This can clearly be demonstrated by
resizing a specially crafted image. It affects all images and worsens the image
quality by making them "darker".
A more in depth explanation and how to fix this problem can be found on the
website http://www.ericbrasseur.org/gamma.html?i=1
STEPS TO REPRODUCE
1. Download "gamma_dalai_lama_gray.jpg" from the attachments
2. Open gamma_dalai_lama_gray.jpg with Krita
3. Proportionally resize the image by doing:
3.1 Image -> Resize Picture
3.2 Tick "Constrain Proportions" and Select "%"
3.3 Pick 50% for width and heigth
3.4 You can pick any one of the filters except Nearest Neighbour
3.5 Press OK
ALTERNATVE STEPS TO REPRODUCE
1. Step 1 and 2 as above
2. Scroll down the mouse wheel until the zoom factor is 50%
OBSERVED RESULT
The image comes out grey or grey with some barely visible outlines.
EXPECTED RESULT
Picture with natural colors.
SOFTWARE/OS VERSIONS
Archlinux with kernel 5.6.17
KDE Plasma:
(available in About System)
KDE Plasma Version: plasma-desktop 5.19.3-1
KDE Frameworks Version: plasma-framework 5.72.0-1
Qt Version: qt5-base 5.15.0-4
ADDITIONAL INFORMATION
krita 4.3.0-1
amdgpu-core-meta 19.30_934563-1
xf86-video-amdgpu 19.1.0-2
mesa 20.1.3-1
lib32-mesa 20.1.3-1
libva 2.8.0-1
libva-mesa-driver 20.1.3-1
lib32-libva-mesa-driver 20.1.3-1
mesa-vdpau 20.1.3-1
lib32-mesa-vdpau 20.1.3-1
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