pammasksharpen

   Updated: 08 May 2004
   Table Of Contents

NAME

   pammasksharpen - Sharpen an image via an unsharp mask

SYNOPSIS

   pammasksharpen maskfile [inputfile]

   All	options	 can be abbreviated to their shortest unique pre-
fix. You may use
   two hyphens instead of one. You may separate	 an  option  name
and its value
   with white space instead of an equals sign.

EXAMPLES

   pamgauss   5	  5  -sigma=.7	-tupletype=GRAYSCALE  |	 pamtopnm
>gauss.pgm
   pnmconvol gauss.pgm myimage.ppm >blurred.ppm
   pammasksharpen blurred.ppm myimage.ppm >sharpened.ppm



DESCRIPTION

   This program is part of Netpbm.

   pammasksharpen  reads a Netpbm image as input and  produces	a
sharpened
   version of it, in the same format, as output. It does this via
an unsharp
   mask, which you supply as another Netpbm image.

   An unsharp mask is generally a blurred version of the original
image. The
   sharpening computation is simply to double the value of a pix-
el in the input
   and subtract the value of the identically located  pixel  from
the unsharp
   mask.  This	causes pixels that are brighter than their neigh-
bors to get even
   brighter, while pixels that are dimmer  than	 their	neighbors
get even dimmer.
   This	 makes	edges -- places where pixel values change quickly
in space --
   stand out more.

   The unsharp mask must be the same dimensions and have the same
maxval as the
   input image.

SEE ALSO

   pnmconvol,  pamedge, pamsharpness, pamsharpmap, pamarith, pnm,
pam

HISTORY

   pammasksharpen was new in Netpbm 10.23 (July 2004).
     _________________________________________________________________



Table Of Contents

     * NAME
     * SYNOPSIS
     * DESCRIPTION
     * HISTORY
     * SEE ALSO

UNIX/Linux commands referenced on this page:

1. pamgauss
2. pnmconvol
3. as
4. which
5. pamedge
6. pamsharpness
7. pamsharpmap
8. pamarith