pbmtopgm1

Usage

Overview

This program is part of Netpbm(1) .

pbmtopgm reads a PBM image as input. It outputs a PGM image in which each pixel's gray level is the average of the surrounding black and white input pixels. The surrounding area is a rectangle of width by height pixels.

In other words, this is a convolution. pbmtopgm is similar to a special case of pnmconvol.

You may need a pnmsmooth step after pbmtopgm.

pbmtopgm has the effect of anti-aliasing bitmaps which contain distinct line features.

pbmtopgm works best with odd sample width and heights.

You don't need pbmtopgm just to use a PGM program on a PBM image. Any PGM program (assuming it uses the Netpbm libraries to read the PGM input) takes PBM input as if it were PGM, with only the minimum and maximum gray levels. So unless your convolution rectangle is bigger than one pixel, you're not gaining anything with a pbmtopgm step.

The opposite transformation (which would turn a PGM into a PBM) is dithering. See pamditherbw.

Options

There are no command line options defined specifically for pbmtopgm, but it recognizes the options common to all programs based on libnetpbm (See
Common Options ⟨index.html#commonoptions⟩ .)

Document source

This manual page was generated by the Netpbm tool 'makeman' from HTML source. The master documentation is at

http://netpbm.sourceforge.net/doc/pbmtopgm.html