The Bitmap to Icon Wizard lets you create high-quality, multi-size icons from bitmap files. It supports generation of icons with transparency: even 32-bit, alpha-channel transparency. Bitmap2icon takes a large bitmap, which must have a clearly defined background colour if the icon is to have transparent areas, and resamples it to produce device images and an alpha mask.

Bitmap2icon supports four colour depths (32-bit with alpha channel, 24-bit, 8-bit, and 4-bit) and five icon sizes (256x256, 48x48, 32x32, 24x24, and 16x16). The application employs an optimized octree to generate 256-colour images. It dithers 256 and 16 colour images using Floyd-Steinberg. You can choose which colour depths and sizes to use in your icon file.