Improves rgb -> gray16 conversion
Fixes Ticket3422
The pam and png output files look visually similar, in both cases the
dynamics increase to 0x0 -> 0xfffb.
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
diff -w is not a standard option. This fixes the reference files
to match what the tests actually output and switches to using the
standard diff -b which is sufficient to handle different line ending
styles.
Signed-off-by: Mans Rullgard <mans@mansr.com>
