halftone(6D)

NAME
     halftone - half-tone an image

SYNOPSIS
     halftone inimage outimage freq angle [patternno]

DESCRIPTION
     halftone converts the input image into a halftoned image, using
     Hollaway's technique.  The density of the halftone screen is controlled
     by the floating point value freq.  Smaller values of "freq" make a larger
     dot pattern.  The angle of the halftone patterns is controlled by the
     argument "angle".  The integer argument "patternno" selects the halftone
     pattern.  0 is the default and creates a dot pattern.  A pattern value of
     1 will create a line screen, while 2, 3, 4, and 5 create other halftone
     patterns.