Makefile

   1 %g.jpg: %.jpg
   2         convert $< -set colorspace Gray -separate -average $@
   3 %g.png: %.png
   4         convert $< -set colorspace Gray -separate -average $@
   5 %g.pdf: %.pdf
   6         gs \
   7                 -sDEVICE=pdfwrite \
   8                 -sProcessColorModel=DeviceGray \
   9                 -sColorConversionStrategy=Gray \
  10                 -dOverrideICC \
  11                 -dCompatibilityLevel=1.5 \
  12                 -o $@ \
  13                 -f $<