Image segmentation

Hi All,

I have an image which contains the following features buildings, cars, trees etc. I detected the buildings using the code DeltaE done by Image Analyst and would like to classify buildings in one common class. Is there any method/function to do that?

Thanks in advance,

Pugazh

Answer 1

[Image Analyst]

You have to decide what constitutes a building. It may be the color but is there are other things that color then you'll have to add shape or other features. Maybe try the "SURF" algorithm - see wikipedia.

[Pugazhendhi]

Hi,

Is there any way to create multiple roi by using imfreehand function.

[Image Analyst]

Yes, just call it multiple times and keep track of the coordinates returned each time. You can make a mask if you want with poly2mask.

[Pugazhendhi]

nroi=3;

for mroi = 1:nroi;

h=imfreehand;

mask=h.createMask;

end

maskimage=bsxfun(@times, I, cast(mask,class(I)));

figure, imshow(maskimage);

hi, i am using the above code to create multiple roi, the last roi only visible, the previous roi are gone. can you suggest where i have to modify.

thanks

[Image Analyst]

You're overwriting mask each iteration with a new and different one so only the last one makes it out of the loop. You need to OR the current mask with the last one, except for when mroi = 1 where you want to just assign it.

for mroi = 1:nroi;

h=imfreehand;

mask=h.createMask;

if mroi == 1

maskimage = mask;

else

maskimage = finalMask | mask;

end

end

Or something like that.

[Pugazhendhi]

Thanks for the help, the loop is running for the first time and the second time onwards its throwing an error due to the variable finalMask. Can you pls help me to solve this?

[Pugazhendhi]

Thanks, I got it.

Sorry to trouble you again, Can we able to index the multiple ROI and process.

[Image Analyst]

Yes, if you store the "mask" variable into a cell array:

caMask{mroi} = mask;

Answer 2

[Sukuchha]

show your image and detected building image !

[Pugazhendhi]

Sorry, I am not able to upload the image for your understanding. I would like to Supervised classification on image. Anything can you help me on this.

Thanks.

[Walter Roberson]

http://www.mathworks.com/matlabcentral/answers/7924-where-can-i-upload-images-and-files-for-use-on-matlab-answers