test/lps-roundtrip.test


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#! /bin/bash
# This script tests: pbmtolps pstopnm
# Also requires: gs pamdepth pamscale pnmcrop pnmpsnr

# The ordinary round-trip does not work because of the way ghostscript
# renders: a line is considered wider than a single pixel and all pixels
# it touches are set to black if the output is PBM.  To work around this,
# we tell pstopnm to output PGM at a high resolution (=large dpi value).


test_pgm=${tmpdir}/testgrid.pgm

pamdepth 255 testgrid.pbm > ${test_pgm}

pbmtolps -dpi 72 testgrid.pbm | \
    pstopnm -dpi $((72*12)) -stdout -pgm | \
    pnmcrop -white | pamscale -xsize=14 -ysize=16 | \
    pnmpsnr -target=30 - ${test_pgm}

# ghostscript version 8.71: pnmpsnr lumina 33.14dB

rm ${test_pgm}