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.
pamgauss 5 5 -sigma=.7 -tupletype=GRAYSCALE | pamtopnm >gauss.pgm pnmconvol gauss.pgm myimage.ppm >blurred.ppm pammasksharpen blurred.ppm myimage.ppm >sharpened.ppm
This program is part of Netpbm.
pammasksharpen reads a Netpbm image as input and produces a sharpened version of it, in the same format, as output. It does this via an unsharp mask, which you supply as another Netpbm image.
An unsharp mask is generally a blurred version of the original image. The sharpening computation is simply to double the value of a pixel in the input and subtract the value of the identically located pixel from the unsharp mask. This causes pixels that are brighter than their neighbors to get even brighter, while pixels that are dimmer than their neighbors get even dimmer. This makes edges -- places where pixel values change quickly in space -- stand out more.
The unsharp mask must be the same dimensions and have the same maxval as the input image.
pammasksharpen was new in Netpbm 10.23 (July 2004).