In this elaborate system, the optics can become misaligned, and the scanner needs to be somewhat deep to accommodate the mechanism.
Illumination is provided by a closely packed row of red, blue, and green LEDs to create white light.
LEDs draw far less power used in CCD scanners. CIS also eliminates the elaborate housing typical of CCD systems, so a scanner can be thinner than a laptop. CIS resolution, however, is presently limited to 300 or 600 pixels per inch, and image quality and color fidelity need to be improved.