Bug 505020 - Scaled-up image preview in viewer window becomes blurry when moved from high DPI scaled screen to lower DPI unscaled screen
Summary: Scaled-up image preview in viewer window becomes blurry when moved from high ...
Status: CONFIRMED
Alias: None
Product: Spectacle
Classification: Applications
Component: General (other bugs)
Version First Reported In: git-master
Platform: Other Linux
: NOR minor
Target Milestone: ---
Assignee: Noah Davis
URL:
Keywords: multiscreen
Depends on:
Blocks:
 
Reported: 2025-05-30 15:05 UTC by Nate Graham
Modified: 2025-05-30 20:14 UTC (History)
1 user (show)

See Also:
Latest Commit:
Version Fixed In:
Sentry Crash Report:


Attachments
Viewer window on high dpi scaled screen: nice clear image (460.14 KB, image/png)
2025-05-30 15:05 UTC, Nate Graham
Details
Viewer window on lower dpi unscaled screen: blurry image (196.94 KB, image/png)
2025-05-30 15:06 UTC, Nate Graham
Details
175% screen (395.65 KB, image/png)
2025-05-30 20:09 UTC, Noah Davis
Details
100% screen (119.02 KB, image/png)
2025-05-30 20:09 UTC, Noah Davis
Details

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Description Nate Graham 2025-05-30 15:05:58 UTC
Created attachment 181900 [details]
Viewer window on high dpi scaled screen: nice clear image

STEPS TO REPRODUCE
1. Have two screens, one with lower DPI at 100% scale (in my case 23" 2560@1440), and one with higher DPI set to a higher scale (in my case 14" 2880x1800@175%)
2. Use Spectacle to take a small-ish Rectangular Region screenshot of under 400x400px on the higher DPI screen
3. Drag the viewer window to the other window


OBSERVED RESULT
The image preview becomes blurry


EXPECTED RESULT
The image preview remains sharp, because the screenshot size is smaller than the size of the viewer window, so there are definitely be enough physical pixels to display it scaled up without becoming blurry


SOFTWARE/OS VERSIONS
Operating System: Fedora Linux 42
KDE Plasma Version: 6.4.80
KDE Frameworks Version: 6.15.0
Qt Version: 6.9.0
Kernel Version: 6.14.8-300.fc42.x86_64 (64-bit)
Graphics Platform: Wayland
Processors: 16 × AMD Ryzen 7 7840U w/ Radeon™ 780M Graphics
Memory: 16 GiB of RAM (14.9 GiB usable)
Graphics Processor: AMD Radeon 780M
Comment 1 Nate Graham 2025-05-30 15:06:24 UTC
Created attachment 181901 [details]
Viewer window on lower dpi unscaled screen: blurry image
Comment 2 Nate Graham 2025-05-30 15:08:14 UTC
If you compare both screenshots in an image viewer by scaling them to the same size and rapidly switching between them, you'll see what I mean.

A *little bit* of blurriness in the UI is expected, since the screen has a lower DPI. But the amount of blurriness shown by the preview is far greater, and that's what's unexpected.
Comment 3 Noah Davis 2025-05-30 20:09:34 UTC
Created attachment 181908 [details]
175% screen

When I try to do it myself, it looks more like there's a degree of unsmoothed downscaling rather than blurring.
Comment 4 Noah Davis 2025-05-30 20:09:55 UTC
Created attachment 181909 [details]
100% screen
Comment 5 Nate Graham 2025-05-30 20:14:56 UTC
Yeah, that's more or less what I see too.