You can find many PNG JPEG GIF BMP images on the Internet and convert them to icons for use on your Windows desktop, in applications and much more. Picture to Icon supports 32-bit color depth with an alpha channel, this kind of icon can be used in Windows XP, Windows 7, Vista; now you can create semi-transparent XP icons easily. With just a few clicks, any image you find on the Internet, create in a paint program or any part on your desktop screen can be turned into an icon. 

picture to icon support alpha channel - 32bit

By this tool, you can easily resize an icon to any format. It supports 1x1x1-bit to 256x256x32bit icons. alpha channel can be added or removed from a icon easily.
Picture to Icon uses advanced resampling filters, allowing you to create icons from really small or very large images and still get excellent results, without pixeling or artifact creation during resizing of images. 

 resize icon to all colors icon