User Guide

Operating VRS

VRS User’s Manual

Even something that is technically invisible to the eye, such as a piece of transparent

tape placed on a document, could be detected when contrast is set high enough, since

there is ultimately a transition from the tape to the paper surrounding it.

Let us look at the CORE sample document with the lowest Contrast level—zero. In

addition, to truly see what Contrast does on its own, we will set the brightness value

to zero. When it is necessary, as in the case of the CORE document, brightness and

contrast both contribute to produce the best image. Contrast (edge detection) takes

the primary role in dealing with anything edgy, while the Brightness function deals

with everything else.

If you slide the Contrast slider to a level around 50, and set the Brightness to 29, you

can see how the Brightness slider does not affect the edgy objects, leaving that

completely to the edge detector. The only elements that are affected by the Brightness

slider are the non-edgy objects, typically large surfaces of the same gray level (the

inside of a highlighter, the background of a document, a shading on the document,

the inside of very big text or logos, etc.)

Then when the Contrast slider is on level 50, and you change the Brightness level, it

does not affect the text any more; it only makes the large surfaces white or black.

That’s why there’s a tendency to relate the contrast slider with the foreground or text

and the brightness slider with the background because the higher the contrast, the

clearer your text will be, and the higher the brightness the more the background will

be cleared up. The lower the contrast, the less readable your text will be; the lower the

brightness the darker the background will become.