Re: filtering specific pixels

> i have an original image, of which i used a canny edge detector on.
> then, i have to remove the lines detected.
> but the resultant image from the canny filter is a binary image,
> while my original is an indexed image.
> how do i find the pixel location of the edges(white pixels) in the
> filtered image, then command the filter to do 3x3 average filtering
> on those pixels only in my original image, but not on the whole
> image?

The way I might be tempted to tackle this problem is as follows.

1) Take a copy of your image and apply your 3x3 filter to the lot.

2) Take your Canny image and filter it using something like a
Gaussian with a few pixels standard deviation. This gives you a rough
and ready measure of how close you are to one of your lines. That is
to say it will have a value of '1' when you are sitting on top of a
line, and will get smaller as you move away from it. We can call this
the Alpha image

3) Take your original image and your filtered version of your image
and mix them using something like

Mixed_Pixel = Alpha_Pixel*Filtered_Pixel +
(1-Alpha_Pixel)*Original_Pixel;

What we are doing here is any pixel which is far away from your lines
is pure original image, whereas the closer you get to a line, you
undertake a graceful transition between the original pixel, and the
filtered pixel. When you are exactly on a line you are purely using
the filtered image.

The width of the transition zone is controllable by the variance of
the Gaussian you used to filter your Canny edge image with, and can
be made as wide or as narrow as you require. I think this will
generate a much more pleasing result than just treating the exact
edge pixels shown by the Canny, which is probably only showing the
position of the maximum slope of the edge.

It will obviously automatically work for any image, once you have the
parameters of your 3x3 filter, and the Gaussian variance specified.

Hope this helps

Dave Robinson
.

Relevant Pages

  • Re: filtering specific pixels
    ... >>> but the resultant image from the canny filter is a binary ... >>> on those pixels only in my original image, ... >> What we are doing here is any pixel which is far away from your ...
    (comp.soft-sys.matlab)
  • Re: filtering specific pixels
    ... >> i have an original image, of which i used a canny edge detector ... >> but the resultant image from the canny filter is a binary ... > What we are doing here is any pixel which is far away from your ...
    (comp.soft-sys.matlab)
  • Re: filtering specific pixels
    ... > 1) Take a copy of your image and apply your 3x3 filter to the lot. ... > Gaussian with a few pixels standard deviation. ... > 3) Take your original image and your filtered version of your image ... > undertake a graceful transition between the original pixel, ...
    (comp.soft-sys.matlab)
  • Re: Double hires mode color artifacts
    ... expect of an Apple II, given its resolution and color limitations. ... essentially no change after the window had filled with 14 "dots". ... pixel on host pixel boundaries. ... A filter of 4 bit width in hires should be already sufficent for that. ...
    (comp.sys.apple2)
  • Re: Rookie having problems with some filter code. Any help?
    ... > Frederic Patin's paper titled "An Introduction to Digital Image ... > filter ever written". ... And then constructing a Color pixel from the filtered result? ... I don't think 'Normalizer' is of much ...
    (sci.image.processing)
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