Mixed Artificial Lighting

Chris Brown <cb@...>

I deal with lots of images from museums and art galleries. Often these
have very strong mixed casts which I find impossibly difficult to fix with
any sort of success rate. A typical recent example is a dark bronze statue
lit in a mixture of daylight, mercury halide and possibly something else.
Its cast is bright yellow in the top half, a strong magenta in the lower
half and some very blue highlights for good measure. The nature and
distribution of the various casts make even a selection, erm,
The way I have drastically reduced or eliminated the effects of different
colored lights and various color temperatures in a scene is to:

1) Filter any lights, as best possible, to make the main subject in the
scene film-neutral (i.e. Rosco CC gels)
2) Filter at the lens to assist in acheiving step #1 (i.e. Wratten filters)
3) When scanning, eliminate any remaining color contamination (using the
scanning software) on the scene's main subject.

At this point there will be surrounding areas outside my main subject area
where the color and temperature of the light is not pleasing. I then use
Alpha channels and paths in PS to isolate these areas into groups of similar
contamination. Then, using Curves, Levels, and Selective Color, I eliminate
the unwanted colors.

Tedious but effective.

Chris Brown Photography
Vox: (217) 356-0540 * Fax: (217) 356-1394