bwfilter — apply a 3x3 filter to a black and white bw file
type] [-v ] [-d
applies one of several 3x3 kernel filters to a black and white
It will take a file name or else read from standard input.
The input file size will be assumed to be 512x512
pixels unless the
flags are used to tell it otherwise (see
By default a low pass filter is used. The
flag can be used to specify a different type of filter.
The type choices include:
low pass, the default.
boxcar low pass
Most filters divide the result of the kernel multiplication
by some value about in order to scale it back to a 0->255 range.
For example, the boxcar divides by nine. The
flag can be used to change this divisor.
Some filters also add an offset to their results. The output of
a laplacian for example is "centered" about zero, thus it
adds 128 to the answer to yield a difference from neutral grey.
flag can be used to change this offset.
flag displays the max and minimum values and the kernel information on standard error.
This software is Copyright (c) 1989-2016 by the United States Government as represented by U.S. Army Research Laboratory.