Table of Contents
Advertisement
Changing brightness
This is a simple technique to make an image
brighter.
With the RGB channel selected, place the
smooth-curve cursor on the center of the curve.
Click and drag the curve up. Look at the displayed
image to judge the result. The adjustment can be
very small and still have a significant impact on
the image. Moving the tone curve down makes
the image darker.
Increasing contrast
The contrast of an image can be changed. The
45° line on the tone-curve graph represents the
original contrast of the image. Making the angle of
the tone curve greater than 45° increases the
contrast. Making the angle less than 45° reduces
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 increases 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
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 an image.
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. For
more on color, see section 3.7.
47
Advertisement
Table of Contents
