(following Tips #45 and #46)...
You knew that, right? I learned this many years ago from noted painter
and educator Jewitt Campbell. Shadows are not black unless they're
projected on something white.
Shadows are always a darker shade of the color they're projected on!
And, if you study color theory, like I did for an entire year,
you'll know that accomplishing the darker shade actually calls for a
complimentary color!
So how do you accomplish this? If casting a shadow onto a colored
background, like a texture, or a photograph, go and find a darker
shade within the photo itself. Zoom in, and with the eye-dropper
look for that magic color.
If the scene has an overall green cast, I'd be looking for a red or
russet. If the scene is very warm... reds, oranges or browns, I'd go
shopping for blue. HA! Is that crazy or what!!! Try it ... it works.
After having created the shadow in the color you want, go and adjust
the Transparency using the slider. Watch how natural the scene looks
as you pull out of that shadow. You'll also note that it takes less
opacity to get the job done.
Someone then asked about unusual looking shadows,
so we came along with Tip #47.5...