# ppmdither > Reduce the number of colors in an image by applying dithering. > More information: . - 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}}`