Honeywell HH490 User Manual page 162

Example:
Exposure at 7874E with fluorescent
lighting:
G - Gain
Gain is used in Manual Style only (2P). Like a volume control, the gain modifier
boosts the signal and multiplies the pixel value. As you increase the gain, the
noise in an image is also amplified.
Example:
Gain at 1G:
W - Target White Value
Sets the target for the median grayscale value in the captured image. For
capturing close-up images of high contrast documents, a lower setting, such as
75, is recommended. Higher settings result in longer exposure times and brighter
images, but if the setting is too high, the image may be overexposed. Target White
Value is only available when using Photo Style (1P).
148
(default)
1G No gain
2G Medium gain
4G Heavy gain
8G Maximum gain
n
W Range: 0 - 255
Exposure at 100E with fluorescent lighting:
Gain at 4G: Gain at 8G:
(Default = 125)
HH490 User Guide