Week 5
Remove isolated pixels & Destriping
After we discovered that we can use the ImageVision library, we had
to extend it. The way a X-Ray image goes through our application is:
- Sharpen
- Edge detection
- Threshold
- Remove isolated pixels
After that we should have a binaerised image which contains only the
contours of the bones. But we learned that the original image contains
stripes from scanning. If we only go through the four above steps, we
get horizontal stripes in the result which makes the image unusable.
That means - we have to develope a destriping class...
A class which removes the isolated pixels joined the 5 files from the
third week.
[Download (TGZ, 7kB)]
The source
There are only minor changes to the
Makefile,
view_main.cc,
view_ilop.cc and
view_tool.cc.
The header file contains
now the class definition for remIsoPix. The out commented class
definition was the first try
(view_rip.cc). It works
but is very slow, because it uses the get/setPixel() interface
of ImageVision library. The second class definition
(view_rip2.cc) descripts
the recommended way. It is much faster, because it works on the
image data.
The destriping problem
(added in week 10, because it is a
real problem)
We are working with scaled images (less then half the size of the
originals) and while doing all this image processing we discovered
some nasty interfering horizontal lines. As we have to implement an
contour following algorithm, which will get confused with these lines,
we have to get rid of them. But how to get rid of lines without lose
image information? The first few approaches I (Matthias) did, didn't
work at all. (Un)Fortunally I was sick then for nearly a week, so I
didn't follow them any further...
[startpage]
[project part 1]
[project part 2]
[week 1] [week 2]
[week 3] [week 4]
[week 5] [week 6]
[week 7] [week 8]
[week 9] [week 10]
[week 11]
[References]
Because english is not the native language of the authors, we
apologize for any inconvenience.
© 1998 by Matthias Kraft & Gesine Schröter;
EMail to: M.Kraft@fhtw-berlin.de & g.schroeter@fhtw-berlin.de
Last changed: Sunday, 08-Feb-2009 12:42:19 CET