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 Gradient [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 Gradient [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 - Vertical differentiation is used and the output is not photonegative.

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 pixels in the last row and last column.

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