So if we have icons with size 16 and 48, the 32 icon is created from the 48 icon. With sizes of 16, 32, and 48, if one is missing, downscaling is preferred. The missing sizes are generated (obviously).
I also checked in Windows 7 what happens if icon sizes are missing: All other intermediate icon sizes are ignored (they may be used in some area which I didn't check). So the result: Windows XP uses 16, 32, 48-size icons, while Windows 7 (and presumably also Vista) also uses 256-size icons. Badge (for lockscreen): 24x24, monochromatic.Zooming using Ctrl+Mouse wheel: 16, 32, 48, 256.Large symbols: 256 (resized, if necessary).All other options: 256 (resized, if necessary).Right-click->Properties / choosing a new icon: 32.If using a larger DPI, the larger sizes may be used (only checked this a bit in Windows 7).
