/usr/bin/ppm2tiff

/usr/bin/ppm2tiff: invalid option -- '-'
LIBTIFF, Version 4.7.2
Copyright (c) 1988-1996 Sam Leffler
Copyright (c) 1991-1996 Silicon Graphics, Inc.

Create a TIFF file from PPM, PGM and PBM image files

usage: ppm2tiff [options] input.ppm output.tif
where options are:
 -r #		make each strip have no more than # rows
 -R #		set x&y resolution (dpi)

 -c jpeg[:opts] compress output with JPEG encoding
    #  set compression quality level (0-100, default 75)
    r  output color image as RGB rather than YCbCr
 -c lzw[:opts]  compress output with Lempel-Ziv & Welch encoding
    #  set predictor value
    For example, -c lzw:2 for LZW-encoded data with horizontal differencing
 -c zip[:opts]  compress output with deflate encoding
    #  set predictor value
 -c packbits    compress output with packbits encoding (the default)
 -c g3[:opts]   compress output with CCITT Group 3 encoding
 -c g4          compress output with CCITT Group 4 encoding
 -c none        use no compression algorithm on output