Here at MAGIC we have a
collection of aerial photographs from various years and at various scales for
the State of Connecticut. Some years offer more complete coverage than others
and some scales give better resolution than others. Currently, all photographs
are black & white.
There are several ways to
make copies of aerial photographs at the map library.
1. You can take the photo
down to the copiers on the 3rd floor (this is not advised as the copiers are
optimized for text).
2. You can scan a
photograph and print it out at a cost of $1 per copy.
3. You can scan a
photograph and save it electronically.
The benefits of the paper
formats are that they do not need a computer to be utilized and they are easily
transported.
The drawbacks to this
format are that the resolution of the copies is not going to be as good as the
original photograph and there is limited processing you can do with the image.
The benefit of the
electronic format is that it can be used in various software packages and is
highly portable. The drawback is that the size of the file is large, the
resolution is not as good as the original, and a computer is needed to view the
files. There is a distinct trade-off
between resolution and file size.
MAGIC currently has only
black and white photographs. Therefore all of the scanning should be done in
black and white. The current level of information stored in a black and white
scan is 256 shades of grey, or 8-bits. If your work requires greater shading
then you should scan the photograph as a 16 or 32 bit color photograph.
Increases in levels of shading also cause increases in the resulting file size.
Most GIS and image processing package only use 256 levels of shading. We have
collected information on
image formats and software.
