3.
Scanning
Scanning
for screen based images is somewhat simpler and quite different
to scanning for higher resolution print-based images. However,
it is often the case that a high resolution scan needs to
be made first to maintain a quality image. Some images can
scan at 72 dpi and print quite well, however, complex photographic
images with sharp detail tend to need a high res scan and
the following process to decrease the size of the file while
maintaining the quality of the image.
The
Five Steps:
- Scan
at a high resolution - for web photos a minimum of 144dpi
(this makes it easier to calculate proportions)
- Adjust
image as desired
- Scale
image to actual screen size to be used
- Decrease
resolution
- Quantise
image to number of colours required
Ultimately
with resolution, you have to find the best trade off for the
best possible quality image at the lowest file size. The rules
of thumb for achieving this is to:
- Scan
at a higher res than you need - but low enough for your
system to handle changes.
- Only
sample the image down to the desired 72 dpi AFTER performing
ALL processing tasks and BEFORE making a perminant archive
of the scan.
- Avoid
enlarging low-resolution images. Always return to the original
and re-scan or an archived high res version for best results.
Next
page: Decreasing File Sizes
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