What is wrong with my image filter code?

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david
david am 26 Mär. 2015
Kommentiert: Image Analyst am 27 Mär. 2015
Hello i have a code below,it works with n=3 ,but for kernel n=5 or above it doesnt work
error: ??? Attempted to access window(18); index out of bounds because numel(window)=17.
how can i fix it? Thanks.
% code
clear all
image=imread('cameraman.tif');
n=3
nPercent = 10;
[y x]=size(image);
nMaxHeight=round(y*nPercent/100.0);
nMaxWidth=round(x*nPercent/100.0);
for I=1:nMaxHeight,
for J=1:nMaxWidth,
cx=round(rand(1)*(x-1))+1;
cy=round(rand(1)*(y-1))+1;
aaa=round(rand(1)*255);
if aaa>128
image(cy,cx)=255;
else
image(cy,cx)=1;
end
end
end
for i=1:x
for j=1:y
if(i==1 || j==1 || i==x ||j==y)
image_out(j,i)=image(j,i);
else
for l= 1:n
for k=1:n
window(l+(k-1)*3)=image(j+l-2,i+k-2);
end
end
for l=1:(n*n-1)
for k=2:(n*n)
if (window(l)>window(k))
temp=window(k);
window(k)=window(l);
window(l)=temp;
end
end
end
image_out(j,i)=window(5);
end
end
end
figure
subplot(1,2,1);imshow(image)
subplot(1,2,2);imshow(image_out)

Akzeptierte Antwort

Jan
Jan am 26 Mär. 2015
Bearbeitet: Jan am 26 Mär. 2015
If you remove the evil clear all you could use the debugger to step through your code line by line to find out, what's going on.
You create window with n+(n-1)*3 elements, but try to access the values until n*n.
By the way: What about using sort for an efficient sorting?

Weitere Antworten (2)

david
david am 26 Mär. 2015
how can i use sort?

Image Analyst
Image Analyst am 26 Mär. 2015
Don't use "image" as a variable name since it's a built in function.
For the first double for loop, where you threshold the image, simply do:
binaryImage = yourImage > 128;
For the second loop, I'm not exactly sure what you're doing, but you can probably do your second loop without loops using a single call to imfilter(), or conv2(), or medfilt2(), or ordfilt2() .
  8 Kommentare
david
david am 27 Mär. 2015
what about arithmetic filter?did you see anything like that?
Image Analyst
Image Analyst am 27 Mär. 2015
I have no idea what their definition of that is. Of course, all filters are arithmetic in that they use numbers.

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