Primary Color Correction: Tonal Range Primer - The Art and Technique of Digital Color Correction - page 34

The three images you will need to develop this skill are a ramp like the
one on the DVD called “BWRamp” or “ramp from 0-254.psd.” Most non-
linear editing systems (NLEs) have a similar test image built in to them,
or you can even make your own. The ramp should start at 0 percent
luminance on one side (usually the left) and then go all the way to 100
percent luminance on the other side (usually the right). The other image
that you will need is the image of the chip chart from the DVD called
“grayscale_neutral.” And finally, use some of the real video from the DVD
or—better yet—from your own projects to see how these gamma versus
highlights or shadows corrections affect a natural image.
Think of it as a rubber band. At first the image is “loose” and low
contrast. Then you stretch the tonal range so that it goes from 0 to 100
or whatever is natural. Now the rubber band is tightened and contrast is
increased. But you can also grab the middle of the rubber band and pull it
up or down as well, stretching values (adding contrast) in one direction
and compressing them (lowered contrast) in another.
This practice will be greatly enhanced by using a manual control
device with the ability to adjust the highlights, gammas, and shadows all
at the same time, like the Tangent Devices CP-200 or CP-100 that the col-
orists in this topic used. The reason for this is that adjusting the gammas
will obviously have an effect on the highlights and shadows, so if you can
move only one at a time, it will require numerous adjustments back and
forth as the various tonal range corrections interact.
Practice with the ramp image and try to get the dark part of the ramp
compressed in a tight dark band on one end while the bright area is spread
out more. Then reverse that. If you can copy and paste your color correc-
tions in your application, try applying these corrections to real-life images
or to the grayscale chart.
Do the same thing with the grayscale chart. Try to get the chips at the
bottom to all be very close together while spreading the distance between
each chip in the highs and mid-highs. Then do the opposite.
Try to practice on real-life images from the DVD or your own collec-
tion. What if you want to add lots of contrast to the skin tones? What
if you wanted to see lots of detail in the shadows? How could you get
more detail out of the clouds in the sky? Playing gamma against the
other two tonal ranges will deliver these effects. Taking the highlights
or shadows past the point of clipping and then playing with gammas will
take these corrections even further by stretching the contrast over an
even greater area.