Does Windows dpi scaling reduce sharpness of images?

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Larsen83
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Does Windows dpi scaling reduce sharpness of images?

Postby Larsen83 » Mon May 08, 2017 3:57 pm

I have an UHD Display and I'm using 150% dpi scaling in Windows 10. Does that reduce image quality (sharpness) of high resolution images when viewing them in fullscreen mode? Should I enable the zoom on hidpi option? I'm using version 0.86 of XnViewMP for Windows x64.

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m.Th.
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Re: Does Windows dpi scaling reduce sharpness of images?

Postby m.Th. » Wed May 10, 2017 9:37 am

Perhaps but most probably it is unrelated to XnView per se. Anything which is up-scaled reduces the image quality.
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bdragon
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Re: Does Windows dpi scaling reduce sharpness of images?

Postby bdragon » Wed May 10, 2017 9:41 am

m.Th. wrote:Anything which is up-scaled reduces the image quality.


Normally you can use a "sharpen" filter on the image, but you will drastically reduce quality.

However, even if sharpened... if you are using windows DPI scaling... well... that happens "after" the image is loaded and has no impact on the image itself. It's just your perception of the image

cday
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Re: Does Windows dpi scaling reduce sharpness of images?

Postby cday » Wed May 10, 2017 10:48 am

Larsen83 wrote:I have an UHD Display and I'm using 150% dpi scaling in Windows 10. Does that reduce image quality (sharpness) of high resolution images when viewing them in fullscreen mode? Should I enable the zoom on hidpi option? I'm using version 0.86 of XnViewMP for Windows x64.

Isn't it the case [I'm not sure but believe it is the case...] that in Windows, DPI scaling [only] applies to the size of Windows elements, such as icons and menu text, on the screen?

And [separately] if the full image is displayed in full screen, isn't the number of pixels in the displayed image [and hence its sharpness on the screen] determined solely by the total number of screen pixels?

cday
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Re: Does Windows dpi scaling reduce sharpness of images?

Postby cday » Wed May 10, 2017 12:17 pm

Further:

The question, returning to the start, is really whether Windows' DPI scaling rescales the whole screen in a way comparable to using a monitor at a setting below its natural resolution, which generally produces a noticeably degraded display quality.

If it isn't possible to find the answer through research online or reasoning, ultimately the answer could be found, if it isn't too difficult, by setting two DPI scaling values (preferably as far apart as possible) and then making screenshots of an example image in full screen, and saving them using a lossless format such as PNG.

The two screenshots could then be compared side-by-side in a tabbed viewer like XnView, at zoomed-in settings if desired, or otherwise compared.



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