Convert colors to imitate greyscale printing

Question

When reading this question, I started to think whether it would be possible to convert colors to imitate an average greyscale printer (assuming that your screen is calibrated)?

Answer 1

The col2grey (and/or col2gray) function in the TeachingDemos package uses one common method for doing this. The idea is to see what your colors will look like when printed or copied in grayscale instead of color.