Many people have asked me, "My scanner at home can make 300dpi scans, what makes your scanner different?" Well, the difference is in color depth, which is the most important factor in determining scan quality.

Resolution is measured in dpi or ppi, which tells you how many pixels the scanner can capture. The optimal resolution is 2 times the output line screen. For example, 150lpi output requires 300dpi.

Color depth is measured in bits per pixel, and it tells you the number of colors a scanner can see. A 24-bit (8-bit x 3 for RGB) scanner can techinically capture 16.8 million colors, but in reality, only 6 out of the 8 bits are usable, effectively getting only 260,000 colors. A high-end scanner usually captures 48 bits of information, and the best 24 bits are transferred to the computer, delivering the full 16.8 million colors.

Also important is the dynamic range, which measures the lightest and darkest shades a scanner can see. The dynamic range of a scanner usually determines the amount of details that can be captured in the highlights and shadows. Scanners with a dynamic range of 4.0 or higher are generally considered high-end, while low-end desktop scanning have dynamic ranges from as low as 2.0 to 3.3.