http://msdn.microsoft.com/en-us/library/aa511280.aspx
For high dpi
- Windows Vista targets 96 dpi and 120 dpi.
The following tables show examples of scaling ratios applied to two common icon sizes. Note that not all of these sizes must be included in the .ico file. The code will scale larger ones down.
| dpi | Icon size | Scale factor |
| 96 | 16x16 | 1.0 (100%) |
| 120 | 20x20 | 1.25 (125%) |
| 144 | 24x24 | 1.5 (150%) |
| 192 | 32x32 | 2.0 (200%) |
Above icon standards are for .ico file, what if your icons are in JPG, PNG or GIF format; i tried using 96 dpi for jpg, png and gif, I could get 96dpi for jpg and png but not for gif
