Canon CanoScan FB 630U User Manual page 51

chapter 5
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When the Gamma button is clicked, the Gamma sheet is
displayed.
Gamma refers to a process where mid-tones are shifted so that the
lighter colors are lightened and darker colors are darkened. For
example, let us say you scanned a photograph of a subject in a
boat in a tree-lined lake and the shadows of the trees are dark
enough and the white of the boat is light enough, but the blue in
the sky, the blue of the water, and the blue of the subject's
clothing all look the same. By increasing the Gamma value of the
image, the sky might become lighter and the water darker, giving
a better contrast to the image.
Gamma can be set even if there is no image in the
Preview Area. The gamma setting will remain in effect
for the next image previewing or scanning.
Note
Gamma
Slide the Gamma slider to the left or right to set the gamma value
or you can type the value directly into the box. The allowed range
of values are 0.10 to 10.00, inclusive. Lager Gamma values darken
the mid-tones of an image, and smaller Gamma values lighten the
mid-tones. The shape of the tone curve changes to reflect the
current gamma setting for the current Channel, and the image in
the Preview Area changes to reflect the adjustment.
Channel
Click the Channel down-arrow and select one of the primary colors
(Red, Green, Blue) for adjustment or leave the setting at Master to
adjust all colors.
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