#406 grayscale graphics contain colour

[Panagiotis Louridas]

Hello,

Under certain circumstances grayscale graphics do contain colour. This can be problematic when they are to be printed by offset printing.

I attach two files that show the problem. In both files, you can detect that there are colours in the produced PDF pages by running:

gs -o - -sDEVICE=inkcov example_gray_1.pdf
gs -o - -sDEVICE=inkcov example_gray_2.pdf

File example_gray_1.tex uses grayscale shades and file example_gray_2.tex uses patterns (if I remove them, the figure comes out fine in grayscale).

Best Regards,

P. Louridas