# man > ppmdither(1)

> **TLDR:** Reduce the number of colors in an image by applying dithering.
>
- Read a PPM image, apply dithering, and save it to a file:
  `ppmdither {{path/to/image.ppm}} > {{path/to/file.ppm}}`
- Specify the desired number of shades for each primary color:
  `ppmdither {{-r|-red}} {{2}} {{-g|-green}} {{3}} {{-b|-blue}} {{2}} {{path/to/image.ppm}} > {{path/to/file.ppm}}`
- Specify the dimensions of the dithering matrix:
  `ppmdither {{-d|-dim}} {{2}} {{path/to/image.ppm}} > {{path/to/file.ppm}}`

*Source: tldr-pages*

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[ppmdither(1)](https://www.chedong.com/phpMan.php/man/ppmdither/1/markdown)                           General Commands Manual                          [ppmdither(1)](https://www.chedong.com/phpMan.php/man/ppmdither/1/markdown)



## NAME
       ppmdither - ordered dither for color images

## SYNOPSIS
       **ppmdither** [**-dim** _power_] [**-red** _shades_] [**-green** _shades_] [**-blue** _shades_] [_ppmfile_]

## DESCRIPTION
       Reads  a portable pixmap as input, and applies dithering to it to reduce the number of colors
       used down to the specified number of shades for each primary.  The default number  of  shades
       is  red=5,  green=9, blue=5, for a total of 225 colors.  To convert the image to a binary rgb
       format suitable for color printers, use -red 2 -green 2 -blue 2.


## OPTIONS
### -dim
                     mension is a power of 2.  _power_ is that power of 2.  The default is 4, for a 16
                     by 16 matrix.

### -red

### -green

### -blue

## SEE ALSO
       [pnmdepth(1)](https://www.chedong.com/phpMan.php/man/pnmdepth/1/markdown), [ppmquant(1)](https://www.chedong.com/phpMan.php/man/ppmquant/1/markdown), [ppm(5)](https://www.chedong.com/phpMan.php/man/ppm/5/markdown)

## AUTHOR
       Copyright (C) 1991 by Christos Zoulas.



                                            14 July 1991                                [ppmdither(1)](https://www.chedong.com/phpMan.php/man/ppmdither/1/markdown)