Layer Mask and Alpha channels are more or less the same thing. However only the current active layer's layer mask is shown in the Channels palette. Other layers Layer masks are not displayed there however they exists but just not listed in the Channels palette for they are shown in the layers palette. You can have something like up to 8,000 layers in a Photoshop document so up to 8,000 layer mask. You could only duplicate up to 53 of them as named Alpha Channels for Photoshop limits you to 53 Alpha channels in a document.
↧