kmeans image segmentation and confusion matrix
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A sample kmeans image segmentation code as well as for its confusion matrix would be greatly appreciated. Thanks. Note: For a non-grayscale image please.
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Image Analyst
on 4 Oct 2014
See the Mathworks demo of using kmeans() on a color (3D) image: http://www.mathworks.com/products/demos/image/color_seg_k/ipexhistology.html
For the confusion matrix you need to know the "true" class for each pixel that was classified. There may be some function to do that in the stats toolbox that I'm not aware of, but if not it's easy enough to just scan the matrices and make it
confusionMatrix = zeros(numberOfClasses); % Initialize
for col = 1 : columns
for row = 1 : rows
% Find the row and column that these classes
% will have in the confusion matrix.
r = classifiedImage(row, column);
c = trueClassificationImage(row, column);
confusionMatrix(r, c) = confusionMatrix(r, c) + 1;
end
end
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Image Analyst
on 7 Oct 2014
You need to create an image where you have 1 for pixels that are class 1, 2 where pixels are class 2, 3 where pixels are class 3, etc. I guess that should actually instead be
classifiedImage = BW_class_1;
classifiedImage(bw_class2) = 2;
classifiedImage(bw_class3) = 3;
classifiedImage(bw_class4) = 4;
classifiedImage(bw_class5) = 5;
classifiedImage(bw_class6) = 6;
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