[GreenKeys] ascii art generation

[John Foust]

At 04:22 AM 5/25/2013, you wrote:
>whils studying the art of asciiart, I wondered how the overstrike was calculated, is there a lookuptable of the greylevels somewhere online? in a book about this subject dating from the mid 80's there was even a 3times overstrike to get even deeper blacks. i would like to make a small c program to change a jpg to overstrike asciiart this way.

Many of the 1970's computer-room pictures only represented a 
small number of levels of gray...  on the order of ten to twenty.

- John