The moirÄ pattern is caused by a conflict between the dots that make up the printed picture and the dots that the scanner uses to create the image. This is why the moirÄ pattern shows up most often when scanning a printed picture from a newspaper or magazine. The Ofoto Software that is bundled with Apple's OneScanner and Color OneScanner is designed to minimize moirÄ patterns. Scanning directly from a photograph, however, will circumvent the problem entirely.
The following information should help get the best possible results:
Be sure the scanner is set for the device on which you'll be printing or displaying the final version of your scan. The Ofoto scanner software sets the scanning resolution appropriate to that device. Many people think that the highest resolution is always the best, but this is not the case. If, for example, you are printing on a laser printer, and you set the scanner to the high resolution appropriate to a Linotronic printing press, your files will be large, your printing time will be slow, and your scan will be no better than if you had selected the lower resolution. What's important is that the scanning resolution be appropriate for the output device's resolution and image-processing abilities.
Output Device Appropriate Scanning Resoultion
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Monitor 72 dpi
300 dpi laser printer
with standard PostScript
processing (53 line screen) 100 dpi
600 dpi laser printer with
standard Postscript
processing (85 line screen) 150 dpi
300 dpi or 600 dpi laser printer
with standard PhotoGrade
processing (106 line screen) 150 dpi
Separations at 125 line screen 200 dpi
Separations at 175 line screen 300 dpi
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