Real ICO inspection
MakeFileWork validates the ICO directory, every image offset and size, then exports the largest supported icon. Embedded PNG icons are preserved without re-encoding; common uncompressed 32-bit icon bitmaps are decoded locally.
Safe limits
Files are limited to 20 MB, 256 icon images, 4,096 pixels per dimension and 16 megapixels. Unsupported or malformed bitmap variants are rejected explicitly.