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A QUICK GUIDE TO TONE CURVE CORRECTIONS
Bringing out detail in the shadows
This is a simple technique to make a subject hidden in the shadows brighter. Unlike the brightness
level control (page 52), this method of correction will not loose details in the highlight areas of the
image.
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 prescan 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 will make the
subject darker.
RGB
Image processing is a highly specialized and difficult field that takes years of practice to master.
This basic guide to using tone curves covers a few simple procedures to improve your pictures. For
more about digital-image processing, consult your local book dealer about self-help guides on this
subject.
About the tone curve
The tone curve is a graphic representation of the brightness
and color levels of the image. The bottom axis is the 256 levels
of the prescan image (input data) from black to white. The ver-
tical axis is the corrected prescan image (output data) with the
same scale from top to bottom.
The bottom left portion of the graph represents the dark colors
and shadow areas of the image. The middle section represents
the mid-tones: skin, grass, blue sky. The top right section is the
highlights: clouds, lights. Changing the tone curve can affect
the brightness, contrast, and color of the final image.
0
255
INPUT
OUTPUT
255
Shadows
Mid-tones
Highlights
