NAME

unexp - Convert "exponential" files into normal files.

SYNOPSIS

unexp [ -m maxval ] [ -o outfile ] [ -p ] [ -s ] [ -v ] infile

DESCRIPTION

Unexp Converts a file of "exponential" floating point values into an RLE(5) file containing integer valued bytes. Exponential files have N-1 channels of eight bit data, with the Nth channel containing a common exponent for the other channels. This allows the values represented by the pixels to have a wider dynamic range.

If no maximum value is specified, unexp first reads the RLE file to find the dynamic range of the whole file. It then rewinds the file and scales the output to fit within that dynamic range. If a maximum value is specified, unexp runs in one pass, and clamps any values exceeding the maximum.

Files containing exponential data are expected to have a "exponential_data" comment; unexp prints a warning if such a comment doesn't exist. An exponential file should be unexp'ed before attempting to use any tools that perform arithmetic on pixels (e.g., rlecomp(1), avg4(1), fant(1), or applymap(1)) or displaying the image.

Unexp does not allow piped input. The infile must be a real file; the special filenames described in urt(1) are not allowed. ("-" does work, as long as the input is coming from a real file; this is of minimal utility, therefore, as typing unexp - <foo.rle is harder than typing unexp foo.rle.)

OPTIONS

-m maxval: Specify the maximum value (i.e., the data in the file is assumed to be in the range 0..maxval). Only the conversion pass is executed, and values found exceeding the maximum are clamped.
-o outfile: If specified, the output will be written to this file. If outfile is "-", or if it is not specified, the output will be written to the standard output stream.
-p: Print the maximum value found during the scanning phase
-s: Just scan the file to find the maximum, don't generate any output.
-v: Verbose mode, print a message to stderr after scanning or converting every hundred scanlines.

AUTHOR

John W. Peterson

BUGS

Unexp is provided because of the lack of floating point or extended precision RLE files.