Images that you create for stencils and stamps must be saved as a Tagged Image File Format (TIFF) containing three color channels and an alpha channel (RGBA) and be 16 bit in depth. For more information, see Saving images for stencils and stamps.
Loading the image into the tray provides easy access, it is not a requirement for using the image as a stamp or stencil.
To load an image in the Stamp or Stencil trays
Images you place in these directories appear in the associated tray the next time you launch Mudbox.