By selecting individual color channels on the tone curve, adjustments to the overall color of an
image can be made. This can be used to eliminate unnatural color casts or add warmth to a pic-
ture.
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Increasing image contrast
The contrast of an image can be changed. The light blue 45°
line on the tone-curve graph represents the original contrast
of the image. Making the angle of the tone curve greater than
45° will increase the contrast. Making the angle less than 45°
will reduce the contrast.
With the RGB channel selected,
click on the tone curve near the
top and bottom to add two nodes.
Slightly move the top node up and
the bottom node down. This will
increase the angle of the central
portion of the tone curve and
increase the contrast of the image
without making an overall change
in image brightness.
Correcting color
If the image is too red, green, or blue,
simply drag the corresponding color-
channel curve down until the color
appears natural. If the color cast is pre-
dominantly one of the secondary col-
ors, cyan, magenta, or yellow, move
the curve of the complementary color
up. For example, if the image is too yel-
low, move the blue curve up, see the
color example on page 2. For more on
complementary colors, see page 27.
