Bug 465851

Summary: Images look slightly blurry with zoom level < 100%
Product: [Applications] gwenview Reporter: Jan Rathmann <jan.rathmann>
Component: generalAssignee: Gwenview Bugs <gwenview-bugs-null>
Status: ASSIGNED ---    
Severity: normal CC: vasua.ukraine
Priority: NOR    
Version First Reported In: 20.08.2   
Target Milestone: ---   
Platform: Other   
OS: Linux   
Latest Commit: Version Fixed/Implemented In:
Sentry Crash Report:
Attachments: Patch to make Gwenview render images more sharply
Example of blurry rendering in Gwenview, view at 100%
Example of sharper rendering in Firefox, view at 100%
Example of sharper rendering in patched Gwenview, view at 100%

Description Jan Rathmann 2023-02-16 16:40:18 UTC
Created attachment 156309 [details]
Patch to make Gwenview render images more sharply

SUMMARY
Some images (photos) look slightly blurry when they are displayed with a zoom level < 100% (this is the default if I simply open an image file that has a higher resolution than my screen).

STEPS TO REPRODUCE
1. Open a photo in Gwenview with small, fine-grained details.

OBSERVED RESULT
Photo looks slightly blurry.
(see attached screenshot, view at 100%)

EXPECTED RESULT
Photo looks "sharp".
(see attached screenshot of the same image displayed by Firefox, view at 100%)

ADDITIONAL INFORMATION
I discovered this problem by developing RAW files in darktable, wondering why the image looks sharp in darktable but a bit blurry in Gwenview.
I compared the rendering of Gwenview with:
* Firefox
* digiKam
* Eye of Gnome
On all of them it looks "good/sharp".

I get a sharp rendering in Gwenview by replacing Qt::SmoothTransformation with Qt::FastTransformation in one function, see attached patch.
Comment 1 Jan Rathmann 2023-02-16 16:41:31 UTC
Created attachment 156310 [details]
Example of blurry rendering in Gwenview, view at 100%
Comment 2 Jan Rathmann 2023-02-16 16:42:09 UTC
Created attachment 156311 [details]
Example of sharper rendering in Firefox, view at 100%
Comment 3 Jan Rathmann 2023-02-16 16:42:54 UTC
Created attachment 156312 [details]
Example of sharper rendering in patched Gwenview, view at 100%
Comment 4 Bug Janitor Service 2023-10-24 18:07:06 UTC
A possibly relevant merge request was started @ https://invent.kde.org/graphics/gwenview/-/merge_requests/229
Comment 5 John Kizer 2025-03-26 17:39:47 UTC
*** Bug 501351 has been marked as a duplicate of this bug. ***