How to create opacity mask from colored bitmap? For the image (bitmap) below, if I do Create a spite with the image in unreal engine. Create a opacity mask on the spite. Use this image, choose a specific color, such as blue, make its corresponding region the only opacity region on the mask. My question is about the implementation of part 2 and part 3 in Unreal engine, they are quite confusing. If anyone know how to implement it in unity, it would also be helpful. Thanks a lot.