png-bw — convert a Portable Networks Graphics (PNG) format file to a BW format
will convert a
file from its standard input
and produce a black and white
file on its standard output, If the PNG file contains a B/W image the conversion is direct, however, if the PNG file contains a color image, then
by default all three colors are weighted equally. The
uses weighting based on the NTSC primaries and the D6500
alignment white. The
flag applies weights for "typical" CRT phosphor chromaticities
and the D6500 white.
Individual color plane(s) can be selected via the
If one or more of these flags is followed by a value,
the value will be treated as a weight
to be applied to that color
This value is implicitly 1.0 divided by
the number of colors selected for the flags which are not followed
by a value.
png-bw -R -B < file.png > file.bw
will equally blend the red and blue color planes.
png-bw bw_file.png < file.bw
will convert a b/w PNG file to bw(5) format.
png-bw -R0.30 -G0.59 -B0.11 < file.png > file.bw
has the same effect as the
weights are: 0.26, 0.66, 0.08]
This software is Copyright (c) 1998-2016 by the United States Government as represented by U.S. Army Research Laboratory.