MITSUBISHI ELECTRIC DV1248ST - Manual (Page 30)

The best way to select the scan resolution is to match it to the purpose of your
scan job. This is because the higher resolution you use for scanning, the larger the
scanned image file size will become. When resolution is increased above a certain
value, it will only enlarge the file size of the scanned image without improving the
image quality. This value will depend on the original image.
If you are scanning images for displaying on screens, such as web page images, a
resolution of 75 dpi is usually sufficient.
If you are scanning images for output with most printers, we recommend that you
use a resolution of at least 300 dpi.
If you are scanning a text document for OCR, we recommend a resolution of 600
dpi or above.
Scenarios for using a High Resolution Scan
High resolution scans (above 600 dpi) are generally used for professional
applications where there is a need to retain the sharpness and overall quality of the
original images.
Select a resolution (ranging from 75 dpi to 19200 dpi) from the Resolution box.
Alternatively, you may select Custom… to customise resolution. Once you select
Custom…, the following dialog box will appear:
From this dialog box, drag the scroll
bars to adjust the resolution of the X
(Horizontal) and Y (Vertical) axis
independently. This may however,
cause the resolution of the X-axis to
be different from that of the Y-axis.
Consequently, the shape of the
original image will be altered. To
avoid this, you may check the Sync
check box to adjust the resolutions of
the X- and Y-axes simultaneously.
This will constrain the proportions of
the original image.
When you get the desired effect, click on the OK button to confirm your settings
and close the dialog box. If you are not satisfied with the adjustment, click on the
Cancel button to cancel your settings and close the dialog box.