Monitor Calibration: black point
You should be able to distinguish between the patches marked 0 and 10 in the
above grayscale. Patch 0 should be perfectly black, matching the unscanned
portion of your monitor, and patch 10 should be barely visible. In this section
you will adjust monitor brightness so the black point is properly calibrated.
Adobe Gamma, and several web sites, attempt to adjust the black point with
grayscale patches. However, the quality of monitor displays varies
significantly, and attempting to read something out of low-valued patches is
fraught with difficulties.
When the black point is properly set, an RGB value of (0,0,0) will appear as
true black on your monitor. Increase the RGB value slightly and you should see a
slight increase in intensity. The non-scanned area surrounding the displayed
image is an ideal reference for the black point. The goal is to make display
value (0,0,0) match the black of the non-scanned border.
For adjustments to be accurate you need to use consistent lighting when
viewing your monitor. The black point for a brightly-lit room will be higher
than a dimly-lit room. After setting room lights to your standard, minimize any
on-screen applications (including your browser). If there are bright-colored
icons on your desktop, move them to a folder and minimize the folder. You can
easily retrieve them later. It is very important that your screen be completely
black.
Set the desktop background color to black (0,0,0). To set the background
color in Windows, choose Start > Settings > Control Panel, double-click on
Display, and click on the Desktop tab. You can verify the RGB value is (0,0,0)
by double-clicking on the color patch to view the Color Picker dialog box.
Set brightness and contrast to 100%. Adjust the vertical dimensions of the
screen so you can easily distinguish the border between the scanned and
non-scanned areas. To make this adjustment, shrink the view vertically, or move
the view up and down with your monitor controls. This will expose the
non-scanned area. If you shrank the window 2" from the top, then the border
between the scanned and non-scanned area should be 2" down on your screen.
Decrease brightness until the the scanned area blends with the non-scanned
area. If there is a dialog box for monitor brightness, and it is distracting,
mask it so it doesn't interfere with this step. Go back and forth until you've
identified the point where the scanned area starts increasing in intensity. Lock
the setting when the scanned area just starts to become visible.
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