However, in a previous thread - "lens filter" - richard_l noted, "...in order to digitally emulate contrast (colored) filters, one is restricted to the use of color film. With black and white film, the only way to emulate contrast filters is to actually 'paint' over the image".
Tom wrote:
"Sorry, but this is incorrect."
Dear Tom:
If you have a black and white image of a red rose bush with green leaves, and the rose and the leaves are the same shade of gray, how in the world are you going to emulate the effect of a red or green filter? I'm assuming you understand how colored contrast filters work.