Figure 7. Sobel filter for the X-ray in figure 3
Figure 8. Simple histogram equalization of the
X-ray in figure 4
Figure 9-A. A rejected over exposed joint
248
Figure 9-B. Exponential equalization for the X-ray in 9-A,
notice the lighter tone in the middle of the joint
Limitations and Practical Difficulties
This system would produce the expected result by
minimizing the number of rejected X-ray pictures.
However, several practical limitations should be addressed:
Resolution
The current X-ray film capture data and provide excellent
resolution. Converting X-ray pictures from pictorial to
digital would require the use of certain type of scanner.
Currently there are many scanners in the market ranging
from several hundred dollars to hundreds of thousands of
dollars. Resolution and image quality obtained from these
scanners increases with the prices. A scanner with 300
DPI might cost less than a thousand dollars, but the quality
of the obtained image is not suitable for medical diagnosis.
On the other hand, the quality of images scanned with 1200
DPI would be much higher and provide reasonable
resolution for medical diagnosis, but it is much more
expensive
Independent of scanner, the screen resolution for most
commercially available monitors is 1024 X 1024.
Therefore, if an image is scanned with 1200 DPI, and
displayed on a 1024 X 1024 screen, the resolution will be
less.
Size of Data Involved
Independent of scanner and monitor types, the obtained
digitized image would require significant dynamic and
static storage space. For example, a 15 X 16 inch chest X-
ray digitized at 300 DPI would produce an image 4500 X
4800 pixels. This would need 22 megabytes of memory
space. High quality digital image (1200 DPI) would
require 345 megabytes. Any enhancement or restoration
operations would require additional space.
Time
Currently it takes two minutes to obtain an X-ray image.
This time includes taking the picture and developing the
film. In the proposed system, the X-ray would be taken,
would be digitized, and then processed. This would
require additional time especially if a high quality image is
