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Analog Gain
The controls in the Analog Gain palette are used to adjust col-
ors by modifying exposure for each of the colored elements in
the scanner's light source. Gain is measured in Exposure Values
(EVs), the same unit used for exposure compensation on many
cameras. The controls for analog gain consist of four sliders: a
master slider that adjusts exposure for all elements in the
scanner's light source, and separate red, green, and blue sliders
for independent adjustments to the red, green, and blue LEDs.
Exposure Value
Exposure Values are a measure of the quantity of light that falls
on the scanning element (Charge-Coupled Device, or CCD).
At +1 EV, the CCD is exposed to twice the normal amount of
light, while at –1EV, the amount of light is halved. EVs are some-
times referred to as "steps."
Reference: The Tool Chest
To view the effects of analog gain on the image in the preview
area, click the Update button. To return the exposure value
for all LEDs to 0, click Reset.
The current status of analog gain is shown in the information
display in the scan window. If changes are made to analog gain
without redrawing the preview image, a warning icon will ap-
pear in the information display.
Choosing too high a value for exposure may produce "smear"
or other defects in the scanned image.
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