## NAME

         acuity_nightvision_filter - visual  acuity  and  nightvision
         simulations

## SYNOPSIS

          #include "CVIPtools.h"
          #include "CVIPtoolkit.h"
          #include "CVIPconvert.h"
          #include "CVIPimage.h"
          #include "CVIPdef.h"
          #include "CVIPfs.h"
          #include "CVIPhisto.h"
          #include "threshold.h"
          #include "CVIPspfltr.h"

         Image *acuity_nightvision_filter(Image *cvipImage,char  rea-
         son, int threshold, int choice)

          <cvipImage> - pointer to an Image
          <reason> - y = nightvision, n = acuity simulation
          <threshold> - binary threshold for nightvision simulation
          <choice> - visual acuity value (20, 30, 40, ...)

## PATH

         $CVIPHOME/SPATIALFILTER/nightvision.c

## DESCRIPTION

         Performs visual acuity and nightvision goggles  simulations.
         For  visual  acuity, set <reason> to 'n', set <threshold> to
         -1, and specify the desired acuity <choice> as the numerator
         of a standard visual acuity rating, such as '50' to simulate
         20/50 vision.

         For nightvision goggles simulation,  set  <reason>  to  'y',
         select a threshold value (1-154), and set <choice> to -1.

## TYPES AND CONSTANTS

         None

## RETURN VALUES

         A modified image

## HISTORY

         History information recorded: None

## SEE ALSO

         libspatialfiltr

## AUTHOR

         Copyright (C) 1996 SIUE - by Scott Umbaugh,  Mark  Zuke  and
         Kun Luo.