Epson

CCD Scanners
Changed Coupled Devices or "CCDs" are microchips that are usually used as the image sensors in high resolution digital cameras. Epson scanners that feature CCD sensors can create high quality scanned images that are similar to a digital photograph. Because light path of the scanner travels a longer distance before passing through the scanner lens, greater depth of field can be achieved in order to scan sharp and clear images of uneven documents, books or even 3D objects which are placed on the scanner glass. This is especially useful for scanning film whereby the film holder lifts the film higher from the glass surface. CCD scanners can capture higher dynamic range (Optical Density) which captures every detail from film.

Benefits of CCD technology:

• Higher scanning speed.
• Greater depth of field for scanning uneven documents or 3D objects on scanner glass.
• Sharper and clearer details for film scanning.
• Higher Dynamic Range (Optical Density).

CIS Scanners
Scanners using Contact Image Sensor (CIS) technology illuminates red, green and blue LEDs to capture objects placed on the glass. The sensors underneath the glass capture the image through a lens array. Because lesser parts are required to manufacture the scanner carriage using CIS technology, the scanner can me made much smaller in overall size. CIS scanners require lesser power to operate as compared to CCD scanners, which make it possible for portable scanners to be powered by USB. However, as the distance between the object, lens and sensors are close to each other, the scanner has limited depth of field, and hence focus on the part of the scanned item in direct contact with the scanner's glass surface. This issue is rectified as sheet fed scanners have pressure plates to ensure that the documents are flat on the surface when passing through the scanner.

Benefits of CIS technology:

• Lower cost of scanner.
• Small scanner carriage design, which leads to smaller overall size of scanner.
• Low power consumption.
• Less image distortion.