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
❖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 | Low threshold value |
High threshold value | Dynamic threshold mode |
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