The netpbm suite provides a set of general image manipulation programs for tasks like converting, scaling, and colour adjustments of pixelised images. Originally written for Unix, the programs have been ported to other systems. A set of libraries is included to add new programs. This program performs the task of a 2D-plotting program.
Options allow the addition of a key and isolines similar to a topographic map.
Other programs, e.g. Gnuplot can of course also plot 2D data sets, but often not in a form as quick and simple as this one. It essentially performs the inverse operation to a plot program. This task a physicist faces occasionally when preparing a publication to present own data together with those published by colleagues. Ideally, data are exchanged electronically via email and can be easily prepared for plotting. However, if this is not possible and only a paper journal article or a fax is available, the data must be retrieved from these sources.