what's edge detection?

Huh! Today is the most boring day I ever had. You might ask why…
Well… I couldn’t give a good focus on my research, however, my reviva will be sooner….waaaa….what happened to meeee?? Arghhhhhhhhh…
I told my hubby that I couldn’t study well at the office today, therfore I request his permission to study at home. Heh! No need to worry about azzam as we sent him to a friend of mine. And of course I pay her to take a good care of azzam. Nothing in this world are free of charge, except the air that we used to breathe. Thanks God (ALLAH) for everything that you gave me.

Ok, I planned to finish up my future plan, but I’m not in the mood to do that. Thus I read something about edge detection. I’ve been thinking that I should write something about it, at least it shows that I do have a good understand besides; I could improve my writing skills, hehehhe…

Ok… what to you know about edge detection? It’s easy; it is a method of detecting edge. What is edge? Well, some might say such as boundaries of objects and some might say a line that shows a difference between two things. Err.. I shouldn’t say more, but I do believe everyone knows what edge is. But how does a computer detect edges? Note that computer even though they are very useful but they are not as clever as human being.

Now, try to think in what situation that edges might occur?

Come up..think first…

Lazy to think? Or don’t have nuch time to think?
Hehhee
Ok, edges often occur at points where there is a large variation in the luminance values in an image. Agree? Not agree, that tell me what you think…

In computer vision, edge detection is traditionally implemented by convolving the signal with some form of linear filter, usually a filter that approximates a first or second derivative operator. An odd symmetric filter will approximate a first derivative, and peaks in the convolution output will correspond to edges (luminance discontinuities) in the image. An even symmetric filter will approximate a second derivative operator. Zero-crossings in the output of convolution with an even symmetric filter will correspond to edges; maxima in the output of this operator will correspond to tangent discontinuities, often referred to as bars, or lines.
You can read more on this article at

http://homepages.inf.ed.ac.uk/rbf/CVonline/LOCAL_COPIES/OWENS/LECT6/

Opss… I think I should continue doing what I really planned for today. Well sorry if you are not satisfied with my article as there seems to be continue ( subject to my laziness or not, heh!)

Another site that might help, http://ct.radiology.uiowa.edu/~jiangm/courses/dip/html/node91.html






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