Ugly blurry login images

[ANB5Dev]

The documentation mentions in privacyidea-credential-provider/blob/master/doc/configuration.rst:

v1_bitmap_path

The complete path and filename of a bitmap image. This is a customized login image. The image must be a version 3 Windows BMP file with a resolution of 128x128 pixels.

However this results (on Windows Server 2025) in a blurry image, since it's displayed at a larger resolution.

Even PI's default image is different, at 192x192px: privacyidea-credential-provider/blob/master/CredentialProvider/tileimage.bmp

It works fine here to update the PI registry key to point to a custom bitmap that's a 512x512 BMP: this one is scaled down nicely. Of course I've only tested it on this one Windows version, so I cannot vouch for it working everywhere.

But the documented requirement of 128x128 doesn't make sense to me when I look at the MS Credential Provider Technical Reference: it doesn't mention scaling, but lists different V1 cred.prov. tile resolutions per OS version, none of which are 128x128.

(https://www.microsoft.com/en-us/download/details.aspx?id=53556, last updated for Windows 10)

Appendix E – LogonUI image display dimensions

In Windows Vista/7, the image size of the V1 Credential Provider tile is 126x126.

In Windows 8/8.1, the image size of user tile is 200x200, V1 Credential Provider tile continues to be 126x126, but will be centered inside a 200x200 pixel bounding box, background is RGB(70,70,70). The image size of V2 Credential Provider tile under selected users is 43x43.

In Windows 10, the selected User/V1/PLAP credential provider has an image size of 192x192. The ones on the bottom left list is of 48x48. Note LogonUI uses circular image for user and square image for V1/PLAP according to the new design direction. The image size of V2 Credential Provider tile under a selected user is 48x48.

Please consider updating the image resolution to make sure it does not look blurry on LogonUI.

[nilsbehlen]

Hi, thanks for sharing your observation.

It works fine here to update the PI registry key to point to a custom bitmap that's a 512x512 BMP: this one is scaled down nicely. Of course I've only tested it on this one Windows version, so I cannot vouch for it working everywhere.

This is exactly the point: i dont have the time and willpower to test such a thing on all windows versions, therefore the option to set a custom image.

I should update the documentation to the text from the technical reference tho

[ANB5Dev]

Indeed, testing what works and what doesn't for every past, present, and future Windows version would be madness.

I think it'd be safest to recommend the specific resolution from the technical reference for their specific Windows version.

But given that the current PI recommendation of 128x128 and the default image of 192x192 hasn't lead to a stream of bug reports, it also seems safe to assume that past and present Windows versions can handle downscaling properly.