Some scanners can capture 12 bits per pixel per color, which allows them to capture a larger range of detail. Compensating for Unwanted Color Cast Before scanning, determine whether the original image has an unwanted color cast that you might be able to eliminate during the scan. Use the following procedure to make sure that the scanner itself is not introducing a color cast. While color cast is sometimes used for aesthetic effect, its typically undesirable when it is created as part of the scanning process. Calibrate your monitor using the Gamma CDEV included in Adobe Photoshop or a monitor calibration utility.
Calibration compensates for any color casts and shifts in gamma caused by the monitor display.
It is critical to calibrate your monitor before attempting the following test. Create a file in Adobe Photoshop containing an 11-step gray wedge. Print the file, and then scan the printed output back into Adobe Photoshop in the RGB or CMYK mode. Sample the grays in the image to see whether they contain any hue or color tint by using the Info palette and the eyedropper tool. If the grays contain a hue or color tint, then the scanner is adding a color cast.