Segment grid boxes

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Siddharth Mallya
Siddharth Mallya on 23 Mar 2011
rgb = imread('peppers.png');
imshow(rgb)
hold on
M = size(rgb,1);
N = size(rgb,2);
for k = 1:25:M
x = [1 N];
y = [k k];
plot(x,y,'Color','w','LineStyle','-');
plot(x,y,'Color','k','LineStyle',':');
end
for k = 1:25:N
x = [k k];
y = [1 M];
plot(x,y,'Color','w','LineStyle','-');
plot(x,y,'Color','k','LineStyle',':');
end
hold off
Suppose I want to segment and extract individual areas of the grid .. How do I go about it ? Like, which boundary detection algorithm is used for this purpose ?
  2 Comments
Sean de Wolski
Sean de Wolski on 25 Mar 2011
Post an image! How do you expect us to figure anything out when we can't see what you're doing!
Siddharth Mallya
Siddharth Mallya on 27 Mar 2011
http://img703.imageshack.us/i/gridg.png/
This is my image. If I want to segment each block of the grid, should I crop it each time ? or should I use some other approach ?

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Accepted Answer

Walter Roberson
Walter Roberson on 12 Apr 2011
Regular rectangular grids, or potentially irregular spacing?
If it is a regular rectangular grid, crop to contain only full cells, detect the grid line separation, then mat2cell() or blkproc() or blockproc()
  3 Comments
Walter Roberson
Walter Roberson on 14 Apr 2011
Your variables hint at "first row" to "last column" which doesn't sound right. A renaming might be in order.
Now, provided that lc1 and N have been chosen to be on grid boundaries:
mat2cell(img(fc1:N+21,fr1:lc1+31), 21 * ones(1,1+(N-fc1)/21), 31 * ones(1,1+(lc1-fr1)/31))
Siddharth Mallya
Siddharth Mallya on 15 Apr 2011
Thank you so much Walter ! You've been a great help to me .. :)

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More Answers (1)

Pedro Serra
Pedro Serra on 24 Mar 2011
An answer to this question would be really nice. I'm dealing with the same issue:
I have an image upon which I've drawn a grid. I now would like to understand how can I extract individual areas of the grid?
(My final goal is to color specific areas of that grid)
Thanks in advance!
  1 Comment
Siddharth Mallya
Siddharth Mallya on 25 Mar 2011
Well, one way I am thinking now is to crop the image in a for loop .. But i think the computational complexity increasing in this .. So ya, are there any boundary detection algorithm like flood fill with a seed point ?

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