Use Mask Buffer

This option allows a mask buffer to be applied simply to the contents of a source image to select particular regions of the source image. The mask buffer will generally be of a binary nature, such as that created by [;CM Produce contour mask buffer]. The masking operation proceeds in a manner similar to performing a logical AND between the source buffer and the mask buffer (or the logical inverse of the mask buffer), the result being returned to the source buffer.

The masking operation may also be accessed through the <f8> function key from most menus.

Apply mask to which buffer ?

This entry specifies the buffer to be masked. The selected buffer will be made the current output buffer. Extended memory buffers are vectored through buffer 0. The masked image will be returned to this buffer.

Mask this buffer using what buffer as a mask ?

This entry specifies the buffer containing the mask to be used. The contents of the mask buffer will be treated as a binary image: pixels with an intensity less than 255 will be taken as a logical FALSE, while pixels with an intensity of 255 will be taken as logical TRUE. The contents of the mask buffer are not affected by the masking operation.

Positive mask, Negative mask or Quit ?

This choice specifies the polarity of the mask to be used. Choosing a positive mask (<P>) performs the logical operation

           source <-- source AND mask.

The negative mask (<N>) performs

           source <-- source AND NOT(mask).

Specifying <Q> suppresses the masking operation.

Parent menu

Main Menu

DigImage User Documentation

Stuart Dalziel, last page update: 19 February 1996