edge following method code

Dear all,,

is there any reference code about edge following in matlab??

thanks before ^_^a

[Image Analyst]

Graph/network edges, or image edges? Where have you looked so far?

[Elsya Nurul Aini]

it's image edge ^_^

Answer 1

[Image Analyst]

Why do you want to "follow" them? Why not first detect them? Then, once you have the edges, which will have various "strengths" of course, what do you want to accomplish? If you really want to follow them you can use bwboundaries but I doubt you want to do that.

[Elsya Nurul Aini]

actually i'm working for a image processing project and i use a method to determine the edge of image.

in the method, there is 4 step to accomplish the edges of image.

1. determine threshold automically from the image

2. decomposed image with quadtree decomposition according the threshold

3. calculate histogram of each block that have different content and take the mean histogram to determined the contour in each blocks

4. follow the contour using edge following method

now, actually, i've finished up to step 2.

So, can you help me how to calculate step 3, then i can follow the contour??

and what do you think, when this can be calculated, can i use the function bwboundaries??

[Image Analyst]

I'm having trouble with step 3. There will be no different content. That's how quadtree decomposition works. It keeps dividing up the image into homogenous blocks until no block had any contours or different gray levels in it. Of course you specify what "different" means. But let's say that you kept going until no block had a gray level spread more than, say, 5 gray levels. So, by definition the block is uniform to within 5 gray levels and there will be no edge or contours within a block.

[Elsya Nurul Aini]

sorry I'm late to answer.

thank you for explaining this.

I understand more about it now.

does this mean that in the quadtree block, there is no image in it that have a variation of image content?

so, how do I get to take a graylevel value in each block?

whether there are other functions that can be used to divide the image into some blocks besides quadtrees function??