image processing, k nearest neighbor
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Hi, I am trying to make image classification with knn but I stuck in how can I compare selected paint and neighbor pixel value. Thank you
clc;
clear all;
a=imread('coins.png');
b=im2bw(a);
imshow(b);
c=zeros(size(b));
[ptx,pty] = ginput(1);
newdata=[ptx, pty];
[nx,ny] = size(b);
[X,Y] = meshgrid(1:nx,1:ny) ;
ed=sqrt(((newdata(1)-X).^2)+((newdata(2)-Y).^2));
dist=ed(:);
neighbor = mink(dist,400);
num=0;
threshold=201;
ind = ismember(dist, neighbor);
% Extract the elements of a at those indexes.
%num=0;
label=0;
% %find index of neighbor in euc then obtain label
indexes = find(dist);
for i=1:neighbor
if b(indexes(i))==1
num=num+1;
if num>=threshold
label=1;
else
label=3;
end
end
end
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Respuestas (2)
KSSV
el 12 de Jul. de 2019
This is how you can use knnsearch.
a=imread('coins.png');
b=im2bw(a);
c=zeros(size(b));
[ptx,pty] = ginput(1);
newdata=[ptx, pty];
[nx,ny] = size(b);
[X,Y] = meshgrid(1:nx,1:ny) ;
ed=sqrt(((newdata(1)-X).^2)+((newdata(2)-Y).^2));
n = 10 ; % number of neighbor points needed
idx = knnsearch([X(:),Y(:)],[ptx pty],'k',n) ;
imshow(b);
hold on
plot(X(idx),Y(idx),'*r')
plot(ptx,pty,'*g')
3 comentarios
KSSV
el 12 de Jul. de 2019
knnsearch gives you the indices of the neighboring points to a given point. If idx are the indicesm then the pixels for the given points are I(idx).
PS: 1. If you are asking a question for a given answer, don't type it as a answer, continue the discussion in the answer.
2. You have asked a previous question and not closed the question. Please close the previous questions, give acknowledgement to the people who answered you and ask next question.
Image Analyst
el 10 de Abr. de 2023
Here's simple demo, attached, that operates on (x,y) data.
![](https://www.mathworks.com/matlabcentral/answers/uploaded_files/1351049/image.png)
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