
vthresh(1)                   Khoros                    vthresh(1)

PROGRAM
     vthresh - Create a binary image by applying upper and lower
     thresholds to an input image.

SYNTAX
     vthresh

     -i             input image

     -o             output image

     [-l]           lower threshold value

     [-u]           upper threshold value

     [-v]           specifies the non-zero pixel output value

     [-V]           Gives the version for vthresh

     [-U]           Gives the usage for vthresh

     [-P]           Prompts for command line options

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

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

DESCRIPTION
     vthresh generates a binary image by thresholding the input
     image.  The result image is of the same data type as the
     input image.  The output pixel is given the specified non-
     zero value if: 1) only the -l flag is given and the pixel
     value is larger than the lower threshold, 2) only the -u
     flag is given and the pixel value is less than the upper
     threshold, 3) the -u and -l flags are given and the pixel
     value is between the upper and lower threshold, or 4) same
     as 3) but both thresholds are equal and the pixel value is
     same as the threshold level. Otherwise, the output pixel is
     given a zero value.

     An image produced by vthresh is very handy for use as a mask
     image  for  one of the other arithmetic routines.  Note that
     this type of image is NOT a Khoros BIT image!  The  output
     image  is  of the data type of the input image, but the only
     pixel values are 0 and non-zero.

     By choosing the appropriate limits it is possible to iden-
     tify areas in an image that are above or below a certain
     value, or to isolate certain bands of intensities.

REQUIRED ARGUMENTS
     -i     type: infile
            desc: input image

     -o     type: outfile
            desc: output image

OPTIONAL ARGUMENTS
     -l     type: float
            desc: lower threshold value
            default: 128
            bounds: no range checking

     -u     type: float
            desc: upper threshold value
            default: 255
            bounds: no range checking

     -v     type: float
            desc: specifies the non-zero pixel output value
            default: 255
            bounds: no range checking

EXAMPLES
     vthresh -i feath.xv -l 128 -u 202 -v 12 -o thresh.out.xv

     causes all pixels between the values on 128 and 202
     (inclusively) to have a value of 12 in the output image. All
     other output image pixels have the value of zero.

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

RESTRICTIONS
     vthresh does not operate in BIT images.

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

Khoros                    Release: 1.0                          1

