To load a file in which predefined regions of interest (ROIs) have been stored, use theĀ File>>Load>>Other Files>>Open ROI Mask menu item.
A dialog similar to that for white light images opens up, allowing to preview the file to be loaded:
The supported image file formats are TIFF (8 bits), BMP, JPEG and PNG.
For more information on how Mask Images are processed, see the Using ROIs page of the manual.