Change the illustration on the AD FS sign-in page
To change the illustration, the graphic on the left, which is displayed on the sign-in page, use the following Windows PowerShell cmdlet and syntax.
Important
We recommend the dimensions for the illustration to be 1420x1080 pixels @ 96 DPI for displays with 1080p resolution in jpg or png format. A file size of no greater than 200 KB to 500 KB to improve load times.
Set-AdfsWebTheme -TargetName default -Illustration @{path="c:\Contoso\illustration.png"}