I know I've missed the boat...not that mines is better
But I was involved in the
GIMP discussion thread in this subforum.
This took a few mins to do with the Layer Duplication, Layer Desaturation and opacity to 80%. Slight adjust on White Point on Levels.
Not quite mono....just another idea
*edit* Hope you don't mind this addition everyone, just like to highlight GIMP as a freeware package too, I just being using it for a week or so.