• What are masks?
  • Masks are binary images -- objects are white (1), background is black (0).
  • Masks are displayed like other gray level images.
  • Info / size & limits shows this:
    • (size (228 326))
      (min 0)
      (max 1)
      (window-type 'gray-level)
      (array-type bit)                           (Masks have bit as the array type.)
      (zoom 1)
  • Some image operations, such as Filter / distance map, can use other images as masks. In these cases, background is black (0), and object pixels have any other value.
• How do I make masks? All of these make a mask image, which is the same size as the parent image, with the appropriate area with 1's.
  • Select / mask from rectangle            Object is a rectangle, with size and position of the previously drawn image rectangle..
  • Select / make mask                          Object is a rectangle, parallelogram, circle or free hand drawing with cloosed loops..
  • Tools / Profile / mask / filled...        Object is a line or rectangle set up with the Profile Tool..
  • Tools / Blob / mask / ...                   Objects are blobs, or silhouettes of particles.
  • Filter / mask of non zero                  Makes an image with black (0) background into a mask.
  • CLUT / Threshold slider / Threshold / Make mask  Mask of red pixels.
  • TOOLS / Circle / Draw / Mask  Good for arbitrary regions that can be covered with various sized discs.
• How do I use masks?  These operations, among others, use masks:
  • Tools / 2 & 3 Variable / scatter plots / traceback
  • Info / rect stats w mask
  • Tools / data cube / plot / sum spec w mask

Mask from rectangle:

Mask from profile line