I'm trying to read merged RGBA data from PSD format. "Image data" section contains channels (RGBAA... where first A might be a merged transparency or Alpha mask). Can someone tell me how to know what is stored in first A? I noticed that:
when image contains no transparency, but has at least one Alpha mask, then first Alpha channel will contain that alpha mask
when image contains transparency, then first Alpha channel will contain merged transparency and other Alpha channels will contain alpha masks
So how do I reliably differentiate between Transparency and Alpha mask in first Alpha channel?