On the Halftone card, the position of the white crossbar represents a brightness-and-contrast setting. Brightness controls the difference between white and almost white. Contrast controls the difference between black and almost black.
HyperScan makes an initial guess about a good brightness-and-contrast setting for the scan. For many scans, this default setting produces great results—save the image and you’re done!
You can refine the brightness-and-contrast setting as follows:
• Click in a new location (or drag the white crossbar to a new
place). You usually don’t need to click very far from the default
setting to make your adjustment. Use Undo on the Edit menu to
return to the previous brightness-and-contrast setting.