Primary Color Correction: Tonal Correction Tools - The Art and Technique of Digital Color Correction - page 38

Don't Use Brightness or Contrast Controls
Of all of the controls available in most applications, the Brightness and
Contrast controls are the ones that should be avoided. Why? Because
they limit the control you have, compared to other sliders.
Watch what happens on a waveform when you use the brightness
slider to adjust the image of the ramp or the chip chart. The entire trace
of the waveform moves up and down uniformly. Compare this effect
to adjusting the gain. When using gain, there is some movement in the
other tonal ranges of the picture, but the largest percentage of adjustment
occurs only in the highlights of the picture.
Now grade the chip chart or ramp image using the Contrast control.
The Contrast control will compress or expand the entire trace of the
waveform equally from each end of the tonal range by raising the blacks
by an equal amount as it lowers the whites, or vice versa. Good color cor-
rection is all about having control, and Brightness and Contrast rob you
of control.
Good color correction is all about having control, and Brightness and
Contrast rob you of control.
So what do you do if you want to make the picture brighter or add
contrast? Well, “brightness” comes from several things. Bringing the gain
up to its highest legal level is a key one. Sometimes, because of some
very bright highlights, the picture will still seem too dark once you have
raised the gain on those highlights to 100IRE because the middle tones of
the picture—containing much of the real information—were not raised
much. In that case, the real sense of how bright the picture looks is done
in the midtones (more on that in a moment). Sometimes, getting a pic-
ture bright enough may even involve increasing the gain so much that
some of the brightest parts of the image will clip. That is a judgment call
that you need to make in deciding what parts of the image “deserve” to
have the most detail. If the highlights are not important, then you can clip
them to the point where detail is lost in order to rescue detail from the
high midtones and midtones, because clipping out the highest highlights
will also raise the levels of the middle highlights and midtones.
Greater contrast usually comes from setting nice rich shadows using
the setup control and then getting as much of a range as possible between
the darkest portions of the picture and the brightest portions of the pic-
ture. The contrast control rarely works for this purpose because if your
blacks are muddy but your highlights are almost at their maximum level,
for example, then you can only slightly increase contrast before the high-
lights can't go any higher without clipping. If you want lots of contrast,