Konica Minolta IV - Manual (Page 63)

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 picture.
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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
predominantly one of the
secondary colors, cyan, magenta,
or yellow, move the curve of the
complementary color up. For
example, if the image is too yellow,
move the blue curve up, see the
color example on page 2. For
more on complementary colors,
see page 41.