ICO240

ICO240: PngNot32Bit

ICO files can contain PNG files. For various reasons, however, the ICO file format only permits one type of PNG file to be embedded in an icon: files that use an RGBA32 encoding.

You will receive warning ICO240 if the PNG file that is embedded in the icon does not have a 32-bit color depth. Some graphics libraries may reject the icon as malformed if the PNG is not encoded as RGBA32.

You can convince IcoTools to create such an icon. Most commonly, the IcoCrush tool will wind up creating one of these if you pass the PNG through an external tool that is too aggressive about optimizing the PNG file. For example, if you pass the icon through pngcrush, you need to give it the "-c 6 -noreduce" option to force it to emit RGBA32 files.

You might receive this warning if another tool is sloppy about how it embeds PNGs inside the ICO file. If you happen to know exactly which tool generated this icon, please file an issue here on GitHub with that info, so we can improve the documentation and tooling.