The COLOR Workflow - 3D Postproduction: Stereoscopic Workflows and Techniques - page 181

6.7 Real-Life 3D Post: COLOR by Juan Cabrera
6.7.1 Overview
Even with perfect geometry and depth, your shot will look strange if the
color and exposure between the eyes is different. Exposure, black levels,
white point and gamma are among the i rst things to match, as thoroughly
as possible. After that, check color temperature and over-all color correction.
If the cameras you are working with have metadata, make sure the values
make both cameras look as close as possible. The closest you manage to
get them, the better the 3D will look. You can do this in linear or log, with
or without grading reference. But sometimes it helps to have more contrast
and saturation to spot differences easier.
6.7.2 Color Wedge and Polarization
This two guys are not your friends. They make the differences between the
eyes being uneven (You can't get rid of them with an overall color correction,
no matter how thorough you are). Both of them happen mostly with beam-
splitter rigs. Since one camera rel ects on a mirror and the other one goes
through the mirror, this changes the way the light reaches the camera, creating
the difference.
Color wedge is a vertical color difference. Not too difi cult to get rid of.
A grade from top to bottom of your image would help, maybe the top
is slightly green and the bottom slightly red. Pick the one you like best
and match the other one. Do the same with the other eye. Polarization is
trickier, since it will happen more on rel ective surfaces, like cars, metal, glass,
mirrors, etc. This one will force you to create masks or power-windows.
Some advanced systems allow semi-automatic ways of i xing this issue, but
make sure you are not introducing more artifacts.
6.7.3 Lens Flares
These are tough, since they can be completely different in both eyes. Most
of the time, the solution will be to live with them, completely remove them,
or match them in VFX. Some advanced systems provide great tools to get
l ares much closer together (in a similar way to how we i xed polarization)
but it is very difi cult to make them look good in both eyes without going
to Paint and Roto. Sorry, no magic trick here… If you can't afford the VFX,
don't point the cameras to a direct source of light!