what format is an icon file
An Icon file, which usually has the ICO extension, contains one icon resource. Given that an icon resource can contain multiple images, it is no surprise that the file begins with an icon directory: Copy. The idCount member indicates how many images are present in the icon resource. The size of the idEntries array is determined by idCount. There exists one ICONDIRENTRY for each icon image in the file, providing details about its location in the file, size and color depth.