Help request: Image segmentation loop
in [Matlab]
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From: Nghia Le on 15 Apr 2010 21:59 Hi, I am new to medical imaging analysis and matlab. Here is what I am trying to solve, hope you can provide me some guidance: I am trying to segment an image into smaller blocks and analyze data those blocks individually. For example, I have a 20x20 image (grayscale) and I want to segment into four blocks and form a 3-dimensional matrix 5x5x16 that I call 'A' by using for loop and here is my test code: I=magic(20); for m=1:4; for n=1:4; vl=(m-1)*5+1; vh=(m-1)*5+5; hl=(n-1)*5+1; hh=(n-1)*5+5; A(:,:,:)=I(vl:vh,hl:hh) end end Here is my problem, I cannot get A to define in term of m and n. For example if I want to view block A(m=1 and n=3) it would show up I(1:5,11:15). I been searching for the correct code two days and yet to find the solution. Hope you can provide some guidance. Thank you in advanced.
From: ImageAnalyst on 15 Apr 2010 22:40 You should consider using the function blockproc() which is meant for exactly this kind of situation.
From: Nghia Le on 16 Apr 2010 00:48 ImageAnalyst <imageanalyst(a)mailinator.com> wrote in message <c3d1c820-00b0-4ac3-ac1f-43bdf8c4628d(a)v16g2000vba.googlegroups.com>... > You should consider using the function blockproc() which is meant for > exactly this kind of situation. I tried your advice, but can't get it to work. The only problem in my previous code is that I do not know to index matrix A. For example, 'n' in A(:,:,n). Thank you for your response.
From: Ashish Uthama on 16 Apr 2010 10:10 On Thu, 15 Apr 2010 22:59:04 -0300, Nghia Le <nghiatle(a)gmail.com> wrote: > Hi, I am new to medical imaging analysis and matlab. Here is what I am > trying to solve, hope you can provide me some guidance: > I am trying to segment an image into smaller blocks and analyze data > those blocks individually. For example, I have a 20x20 image > (grayscale) and I want to segment into four blocks and form a > 3-dimensional matrix 5x5x16 that I call 'A' by using for loop and here > is my test code: > > I=magic(20); > for m=1:4; > for n=1:4; > vl=(m-1)*5+1; > vh=(m-1)*5+5; > hl=(n-1)*5+1; > hh=(n-1)*5+5; > > A(:,:,:)=I(vl:vh,hl:hh) > end > end > > Here is my problem, I cannot get A to define in term of m and n. For > example if I want to view block A(m=1 and n=3) it would show up > I(1:5,11:15). I been searching for the correct code two days and yet to > find the solution. Hope you can provide some guidance. Thank you in > advanced. I am curious to know why you would want to dice your image this way? add another outer FOR loop for thirdInd = 1:16 ..... A(:,:,thirdInd) = I(vl:vh,hl:hh) ..... end
From: Nghia Le on 16 Apr 2010 14:35
Hi, what I am trying to do is to identify the tumor, normal, or background region by using the wavelet transform on each block to obtain mean and std for each component. After that I will form a ID matrix and use classify function for computer learning process. Concerning your suggestion, I did try the third loop many times and trials, but the output for all A(:,:1), A(:,:,2), A(:,:,3)... is the identical matrix. I am sure there is a simple fix for this, but I do not know how to do it. I will keep posted. "Ashish Uthama" <first.last(a)mathworks.com> wrote in message <op.va9gfioua5ziv5(a)uthamaa.dhcp.mathworks.com>... > On Thu, 15 Apr 2010 22:59:04 -0300, Nghia Le <nghiatle(a)gmail.com> wrote: > > > Hi, I am new to medical imaging analysis and matlab. Here is what I am > > trying to solve, hope you can provide me some guidance: > > I am trying to segment an image into smaller blocks and analyze data > > those blocks individually. For example, I have a 20x20 image > > (grayscale) and I want to segment into four blocks and form a > > 3-dimensional matrix 5x5x16 that I call 'A' by using for loop and here > > is my test code: > > > > I=magic(20); > > for m=1:4; > > for n=1:4; > > vl=(m-1)*5+1; > > vh=(m-1)*5+5; > > hl=(n-1)*5+1; > > hh=(n-1)*5+5; > > > > A(:,:,:)=I(vl:vh,hl:hh) > > end > > end > > > > Here is my problem, I cannot get A to define in term of m and n. For > > example if I want to view block A(m=1 and n=3) it would show up > > I(1:5,11:15). I been searching for the correct code two days and yet to > > find the solution. Hope you can provide some guidance. Thank you in > > advanced. > > I am curious to know why you would want to dice your image this way? > > add another outer FOR loop > > for thirdInd = 1:16 > .... > A(:,:,thirdInd) = I(vl:vh,hl:hh) > .... > end |