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We will select a
scanning quality suitable for your use. The
number of bytes in an image is often very important. A single
image
on a website might take minutes to download if too large (wholly
unacceptable)
but a picture on a colour brochure would not look sharp if the file was
too small.
The quality requirement of
scanned images is dependent upon the
application.
Increasing the quality increases the number of bytes for the file, and
increased number of bytes means slower processing. With many
images,
there is a defining level where an increase in quality does not enhance
the image for the application. Quality is determined by:
1. Colour
Images may be full colour, a limited number of colours, grey or
halftone
(black & white).
2. Image intensity
Image intensity is a measure of the number of dots per inch
(dpi).
If an image has 300 dpi, an image of 1 inch x 1 inch will have 300 x
300
(i.e.90,000) dots of data. If the intensity is doubled to 600
dpi,
the same image will have 600 x 600 (i.e. 360,000 or 4 times the
original)
dots of data, and the file saved will be 4 times the original.
(Yes, we know this Country is metric. However, this is a used
measurement).
3. Scaling
The size of your original image may not be important for the final
use. You may wish to increase or decrease the size. As
explained
for image intensity, the file size will vary accordingly.
4. Saved format
The same file saved under different file formats will have a different
number of bytes. Some formats are suitable for website use, but
others
may be preferential for displays.
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