An Alpha Channel is the part of an image that describes transparency. People use it quite often without even thinking of it. Image viewing and image creation programs’ ability to combine multiple image layers with complex transparency relies on alpha channels, but the users don’t realize it because of good design. The problem comes when the program features do not comply with format specifications when working with alpha channels. Knowing this issue we added an option to ignore incorrect alpha channel. That way it won’t hinder image viewing or processing.
https://www.imageconverterplus.com/help-center/faq/how-to/ignore-alpha-channel/