Binary Scanning/Threshold - Ricoh IS450 Operating Instructions Manual

6. Appendices

Binary Scanning/Threshold

The binary scanning function converts the original into black and white image data. If the original
contains any intermediate colors, they are compared with the threshold value and determined to be
either black or white accordingly. The threshold value can be set to any of 255 gradations; any
intermediate colors that are brighter than the threshold value are scanned as "white," and those that
are darker than the threshold value are scanned as "black." This mode should be used to scan
originals that have no intermediate colors and consist of only two colors, such as text or line
drawings.
The threshold value should be set according to the intensity of the original. For example, setting
a high threshold value when scanning faint text will produce text that is much clearer. Conversely,
setting a low threshold value when scanning an original that is on a colored background (such as
text on colored paper) will eliminate the background color from the scan.
There are two modes for the threshold value setting:
Limitation
During double-sided scanning, this function is valid only for the front side of the original.
Standard mode
Any one of 255 values can be set.
Dynamic threshold mode
This function is valid only when the optional Image Processing Unit Type A is installed.
With this mode, the optimal threshold value (given the brightness of the original) is set
automatically.
Original
High threshold value
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Low threshold value
Dynamic threshold mode