About color printing
How input determines output
Successful reproduction of color images depends on a number of factors, starting with the differences in how the various technologies that affect the image translate and display the color.
Scanners Scanners are able to capture colors only as red, green, and blue (RGB). Two types of scanners are used today: drum and flatbed scanners. A flatbed scanner does not have as much color range as a drum scanner.
•A drum scanner uses a photomultiplier tube (PMT) that is very sensitive and accurate. The original document is attached to the drum which is rotated past a group of sensors - one each for red, green, and blue, and a fourth that sharpens the digital image. An internal computer usually performs the RGB to CMYK (cyan, magenta, yellow, black) conversion.
•Flatbed scanners use a less expensive and less accurate charge coupled device (CCD) sensor. The original is placed on a flat glass surface and the array of CCD sensors passes by the original, and collects the red, green, and blue data. RGB to CMYK conversion is usually performed on a computer workstation.
Key point: The resolution at which the image is initially scanned and digitized determines the quality of the final output and limits the degree to which the image can be enlarged without loss of final printed quality.
2 About color printing
DocuColor 5252 Operator Manual |
