User Guide

Chapter 2
40 VRS User’s Manual
gray) becomes white and everything below that number becomes black. Black pixels
are assigned a value of 1, and white pixels are assigned a value of 0. Because the
threshold level influences the brightness of the resulting image, we also refer to the
threshold level as the brightness level. So in VRS, the Brightness slider on its own acts
as a simple threshold level.
Simple Thresholding
Simple thresholding is fine for black text on white paper, but it is tricky when you
have a combination of dark and light text and lines, and dark and light background
surfaces on one page. Figure 2-31 shows a good example of this kind of document.
Figure 2-31. Color Scan of Original Document
A color or 24-bit image is an exact representation of how the original document looks,
much like a photograph of the original. A 24-bit image can contain more than 16
million different colors and is capable of showing all the shades, as well as the darkest
and faintest elements of a document.
It is important, however, to point out that while a 24-bit image can be converted to a
grayscale or a black and white image, a grayscale or black and white image cannot be
converted to a color image. Just as a photo taken on black and white film cannot be