A mask is a 256 color Grey Scale bitmap similar to a stencil. Masked areas are represented by an opaque red color. Masks, in PSP 5, are easier to work with than they were in PSP 4, allow for greater flexibility due to the layer function and can now be saved to Disk or Alpha Channel. There are three choices in the New Mask drop down menu. The pixel color luminance controls the amount of masking.
Darker colors produce more masking while lighter colors produce less.
Colored pixels are covered by the mask while pixels without color are not masked at all. Invert mask data reverses the mask transparency causing black to become white, white to become black and shades of grey to become their mirror transparency. Editing the mask results in uncovering masked areas. Editing the mask results in creating the masked portions. An existing mask may also be applied to an image.