Epson 660 - Manual (Page 57)

T HRESHOLD T AB
The Threshold tool is very useful when you scan line-art images or scan documents for OCR use. You may
use this function to adjust the quality of line art images or eliminate unwanted dots in the document to
improve the accuracy of recognition.
Note: This function is only applicable when you select Line Art as the Image Type.
The x-axis in the histogram represents the brightness level of the pixels in
the image (from 0 to 255, from left to right). The y-axis represents the
quantity of pixels.
To adjust the threshold value, drag the triangle below the histogram or enter
the threshold value in the Threshold entry box directly. For example: