[Tig] instinctive contrast

[Rob Lingelbach]

Something I think all experienced colorists know instinctively  
deserves a
scientific explanation, if someone here would like to attempt one.
Take a color image, make it look the way you think it should, and then
extract all the color, making it pure black and white.  Unless you're
specifically looking for low contrast, you will now need to dial in
significant amounts of contrast (drop the blacks, raise the whites).
(the only other exception I can think of to this formula is if the
original image was extraordinarily high in contrast when it was in  
color.)

We know that detail is a function of luminance, not color, but I'm
interested in a more complete explanation of this phenomenon.

And something related occurs when originally-shot
black and white is colorized without regard to original contrast, such
as with the Turner library as shown on that cable channel of colorized
films.  The balance of shadows and highlights goes all wacky.

Rob
--
Rob Lingelbach
http://www.colorist.org/robhome.html
rob at colorist.org    rob at calarts.edu