Canon FB636U, FB630U manual Adjusting the Image with Gamma Settings, Setting the Gamma

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Adjusting the Image with Gamma Settings

An image scanned with Plug-in Module CS-U is a composite of individual square dots. Each dot contains information that defines its level of brightness. Plug-in Module CS-U can manipulate this data and reproduce adjusted images on the screen. This type of data conversion is referred to a gamma adjustment.

The data created when the scanner scans an original is called input; the image displayed on the screen is called output. When this input and output data are plotted on the same curve, this is called a gamma curve. By changing the gamma curve, you can adjust the brightness of an image.

Plug-in Module DISPLAY

SCANNER

OUTPUT

BRIGHTNESS

HIGHLIGHT

Gamma curve

A straight or curved line indicates the gamma status.

SHADOW

SHADOW HIGHLIGHT

INPUT BRIGHTNESS

Setting the Gamma

You can use one of four methods available in the Color Correction dialog box to set the gamma curve. A description of each method is provided on the following pages.

Using the slider bar — Adjusts the brightness and contrast of the original image. (p. 44)

Setting the gamma value — When you cannot do the optimum setting with the menu. (p. 48)

Using the menu — Set to match the display type. (p. 46)

Setting the graph — Fine adjustment of

the gamma graph. (p. 50)The settings you perform in the Color Correction dialog box can be saved to a file and opened again whenever you need them.

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