Large Format Color Scanners

Fujitsu fi-6130 Duplex Scanner (PA03540-B055)
For almost all applications in which art or beauty is given primacy, the use of a color scanner is imperative. Digitalizing of portraits, indigenous textile designs, and large paintings call for the use of large format color scanners. The particular application in question may be best suited by color scanners of either flatbed-type or drum-type scanners. The choice of imaging technology between the traditional scanner using charge-coupled device (CCD) and the less expensive alternative using contact image sensors (CIS) should also be made judiciously.



When dealing with paintings and works of art, a CCD scanner is preferred so as to obtain best image quality, uniform color, and wide dynamic range. It is also ideal for scanning whole open books to obtain an image with little or no distortion. The geometric accuracy of this method is, however, inferior to that of CIS, and hence the latter are more suitable for scanning maps, engineering drawings, etc. The CIS scanner also has better resolving power since the scanned image is of the same size as the original. The resolution of the scanner is specified in dots per linear inch (dpi). The higher the resolution in dpi, the sharper is the scanned image. However, more resolution normally results in a larger image, requiring more memory for storage. The trade-off between the two depends on the use of the scanner. For example, official maps have to be scanned with much better resolution than the embroidery on a shawl. Large Format Scanners commonly available in the market have an optical resolution in the range of 150dpi to 800dpi, which would be sufficient for most general applications. The larger the scanned image, lesser is the enlargement involved, and lower is the resolution required. Highest resolution is desirable for scanning films.



Speed is another important criterion that influences our choice; speed is usually expressed in inches per second (ips) at a particular dpi. At a higher dpi, the speed will be less. For comparison, the speeds of all scanners are usually evaluated at 200dpi optical resolution, or at half the best optical resolution it provides. Most of the commonly available color scanners have speeds less than 300ips. Thickness of the media to be scanned is yet another factor to be considered when selecting the scanner type.