1 files changed, 22 insertions, 0 deletions
diff --git a/test/lps-roundtrip.test b/test/lps-roundtrip.test
new file mode 100755
index 00000000..f30062a8
--- /dev/null
+++ b/test/lps-roundtrip.test
@@ -0,0 +1,22 @@
+#! /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}