u-bw [-l] < u_shorts > bwfileU-BW(1)
NAME
u-bw - convert unsigned shorts to unsigned chars (8-bit bw data)
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SYNOPSIS
DESCRIPTION
u-bw reads a stream of 16-bit unsigned short integers from standard input and writes a stream of 8-bit unsigned chars to standard output, producing data suitable for use as a bw(5) black and white image or any other unsigned char data stream.
By default each unsigned short is reduced to a single byte by taking the high-order byte (a right shift of 8 bits), which scales the full 0-65535 range down to 0-255. With the -l option the low-order byte is kept instead, effectively taking each value modulo 256.
Both standard input and standard output must be redirected; if either is a terminal u-bw prints a usage message and exits. Data is processed in blocks of 512 values, so the byte ordering of the shorts is that of the host machine.
OPTIONS
- -l
-
Keep the low-order (least significant) byte of each unsigned short rather than the default high-order byte. This is equivalent to taking each input value modulo 256.
EXAMPLES
Example 1. Down-scale 16-bit samples to an 8-bit bw image
u-bw < heightfield.shorts > heightfield.bw
pix-fb -F /dev/X heightfield.bwConvert a file of unsigned shorts (for example a 16-bit elevation or sensor grid) into 8-bit bw(5) data by taking the high byte of each sample, then display the result on a framebuffer with pix-fb(1).
Example 2. Keep the low byte to inspect fine detail
u-bw -l < data.shorts > low.bwRetain the least significant byte of each short instead of the high byte, useful for examining the low-order bits of the source values.
SEE ALSO
brlcad(1), u-a(1), u-d(1), u-f(1), bw-d(1), bw(5)
AUTHOR
BRL-CAD Team
COPYRIGHT
This software is Copyright (c) 1989-2026 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