Resolution Unit - Microtek ArtixScan 4500t Reference Manual

B. Resolution list box
This provides predefined resolution values for easier selection of the resolution
setting.
To select your setting, press the up/down arrows next to the Resolution box, and
choose your setting from the list box.
C. Resolution unit
The unit of measurement for resolution is in ppi (pixels per inch) or lpi (lines per
inch). Take note that lpi settings are dimmed if the ruler unit is in pixels.
To select your resolution unit:
• Choose ppi if your scanned images are intended for on-screen display. In this
case, you need not go higher than the target resolution of your monitor
(usually 72 dpi for Macintosh and 96 dpi for Windows). A higher resolution
value will simply increase the file size of your image without any perceptive
improvement in image quality.
• Choose lpi if your scanned images are to be printed. If you choose 1x, for
instance, your scanned image will be printed at 133 lines per inch, resulting
in a 133-dpi image. At 1.5x, the image will be printed at 199.5 dpi; and at 2x,
the image will be printed at 266 dpi. The Custom option allows you to set an
lpi value of your own specification.
In choosing an appropriate lpi value, keep in mind that if the resolution is too
low, the image becomes pixelized, resulting in a deterioration of image
quality. (Pixelization is the process in which the Postcript language uses a
single pixel's color values to create more than one halftone dot.) Conversely,
if the resolution is too high, the file size becomes unwieldy, and your file ends
up containing more information than the printer needs, slowing down the
file transfer and the printing process.
Reference: The Settings Window 63