I have successfully made a few models by importing masks from PNG files with transparencies, however I have encountered a problem. I have a project where some of the masks import and some of them do not. Coincidentally, the masks that import correctly are landscape, and the ones that do not are portrait. all the PNG files were created the same way using photoshop. The portrait images do not create a mask when trying to import the PNG as a mask, however the photoscan masking tools do still work. I can send sample files if needed.
Photoscan Standard 0.9.1 Build 1703
Windows 8, 64 bit