BW-D(1)

NAME

bw-d - convert black-and-white unsigned bytes to double-precision binary

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SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
SEE ALSO
AUTHOR
COPYRIGHT
BUG REPORTS

SYNOPSIS

bw-d [-n | scale] < unsigned_chars > doubles

bw-d reads a stream of unsigned 8-bit bytes (such as the pixel values of a bw(5) black-and-white image) from standard input and writes a stream of machine-native double-precision (8-byte) binary floating point values to standard output.

By default each byte is copied to its corresponding double value unchanged (0 to 255). If a numeric scale argument is supplied, every value is multiplied by that factor before output. The -n option is a shorthand that normalizes the data by scaling the 0-255 input range to the 0.0-1.0 floating point range.

Because the output is raw binary, bw-d refuses to run when standard input is a terminal. The inverse conversion, from binary doubles back to unsigned bytes, is performed by d-bw(1).

This command is deprecated and is scheduled for removal; it prints a deprecation warning on startup.

OPTIONS

-n: Normalize the data by scaling the 0-255 input byte range to the 0.0-1.0 output range (equivalent to a scale of 1/255).
scale: Multiply every input byte by this floating point factor before writing it. Defaults to 1.0 (a straight 0-255 copy). Cannot be combined with -n.
-h, -?: Print a usage message and exit.

EXAMPLES

Example 1. Normalize a black-and-white image to the 0.0-1.0 range

bw-d -n < image.bw > image.d

Converts every pixel byte in image.bw to a double in the range 0.0 to 1.0, producing a normalized binary double stream suitable for signal processing tools such as dmod(1) or dstats(1).

Example 2. Scale and round-trip through the double pipeline

bw-d 0.5 < image.bw | dmod -a 0.1 | d-bw > brighter.bw

Converts the image to doubles at half intensity, adds a constant offset with dmod(1), and converts the result back to a black-and-white byte stream with d-bw(1).