All options can be abbreviated to their shortest unique prefix. 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.
This program is part of Netpbm(1).
ppmrough generates a PPM image of the specified width, height, and colors. ppmrough tiles the image into semi-rectangular regions with a ragged borders between them. It calculates the fluctuations with the rand() standard C library function.
ppmrough writes the PPM image to Standard Output.
The maxval of the output image is 255 (You can change this with pamdepth).
Use the options -left or -right, respectively, to make vertical borders, and -top or -bottom, respectively, to generate horizontal borders inside the image. Each of these options needs an integer value pixels that determines the average distance of the interior border to the related edge of the image. You may combine the -left, -right, -top, and -bottom options to generate an image with more than one border. The algorithm ensures that you can concatenate two images produced with the same (i.e. -left) value without dislocations.
You specify the dimensions of the generated image with the -width and -height options.
Use the -bg and -fg options to set the background (margin) color and the foreground (interior) color, respectively. If you don't specify any of the -left, -right, -top, and -bottom options, all pixels are set to foreground color. The defaults are white foreground and black background.
Use the -var option to control the "raggedness" of the border. The less its value is the smoother the border is. You can initialize the pseudo-random generator with the -init option.
You could use ppmrough with ppmtopgm to create a PGM transparency mask and use it to roughen up the edges of another image.
Before Netpbm 10.61 (December 2012), this is called -init, and that still works.
This program was added to Netpbm in Release 10.9 (September 2002).