PNG-BW 1 BRL-CAD BRL-CAD
png-bw convert a Portable Networks Graphics (PNG) format file to a BW format
`png-bw` -ntsc -crt -R num -G num -B num in.png > out.bw

## DESCRIPTION

`png-bw` will convert a PNG format file from its standard input and produce a black and white bw 5 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 `-ntsc` uses weighting based on the NTSC primaries and the D6500 alignment white. The `-crt` flag applies weights for "typical" CRT phosphor chromaticities and the D6500 white.

Individual color plane(s) can be selected via the `-R -G` and `-B` flags. 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.

## EXAMPLES

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 `-ntsc` flag.

[The `-crt` weights are: 0.26, 0.66, 0.08]

## SEE ALSO

brlcad 1, png-pix 1, bw-png 1, pix-png 1, pix 5, bw 5

## AUTHOR

John R. Anderson

## COPYRIGHT

This software is Copyright (c) 1998-2024 by the United States Government as represented by U.S. Army Research Laboratory.

## BUG REPORTS

Reports of bugs or problems should be submitted via electronic mail to devs@brlcad.org