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Advanced Imaging 7-5
Scanner Resolutions
Another way to insure high quality output for your images is to
determine the optimum scanning resolution.
Line Art Scanning
For line art, the optimum scanning resolution would be at the same
resolution as the output device, especially when reproduced at the
same size. For example, when printing from your Accel-a-Writer 812
in the 600 x 600 dpi mode, the scanner resolution should be set at
600 x 600 dpi.
Halftone Scanning
The resolution for scanning a halftone is usually lower than that of
the output resolution. Black and white images should generally be
scanned at a resolution of 2 times that of the line screen used, if
printing at 100% size. For example, if a line screen of 95 is used, the
scanner resolution should be set to 190 dpi (95 x 2). If that resolution
cannot be selected, choose the next higher resolution available. Also,
scanner resolutions depend on the size at which the output is printed.
If the previous example were to be printed at 75% of original size,
then the scanner resolution should be set to 142 dpi (95 x 2 x .75).
The formulas for scanning in this section are used to determine the
optimum resolution possible. Scanning the image at a lower than
optimum resolution results in less detail. Scanning at a higher
resolution increases the file size and the processing time, and it may
only slightly increase the amount of detail. The following is a
formula for scan resolution.
desired lpi x 2 x % of original size
