
vgrad(1)                     Khoros                      vgrad(1)

PROGRAM
     vgrad - Sharpens an image by differentiation (gradient).

SYNTAX
     vgrad

     -i             input image

     -o             resulting output image

     [-t]           Choose Vertical Gradient [False] Roberts Gra-
                    dient [True]

     [-p]           Choose Photopositive [False] or Photonegative
                    [True]

     [-V]           Gives the version for vgrad

     [-U]           Gives the usage for vgrad

     [-P]           Prompts for command line options

     [-A [file1]]   Creates the answer file called vgrad.ans or
                    file1

     [-a [file1]]   Uses vgrad.ans or file1 as the answer file

DESCRIPTION
     vgrad differentiates an image to perform image sharpening.
     Two types of gradients are available:
     1) uses the horizontal and vertical pixel differences
     (default)
     2) uses the cross-differences (Roberts gradient).

     Images must be of data storage type byte.

     The output image can be inverted using the -p photonegative
     argument.

REQUIRED ARGUMENTS
     -i     type: infile
            desc: input image

     -o     type: outfile
            desc: resulting output image

OPTIONAL ARGUMENTS
     -t     type: boolean
            desc: Choose Vertical Gradient [False] Roberts Gra-
            dient [True]
            default: false

     -p     type: boolean
            desc: Choose Photopositive [False] or Photonegative
            [True]
            default: false

EXAMPLES
     vgrad -i input.image -o output.image -t 0 -p 0

     This command performs image differentiation on input.image
     and stores the result in output.image.  Horizontal - Verti-
     cal differentiation is used and the output is not photonega-
     tive.

SEE ALSO
     intro(1), verror(3), vgparms(3), vutils(3), lvgrad(3)

RESTRICTIONS
     vgrad operates only on byte data storage type images. The
     gradient is determined for all pixels except for those pix-
     els in the last row and last column.

COPYRIGHT
     Copyright 1991, University of New Mexico.  All rights
     reserved.

Khoros                    Release: 1.0                          1

