I had divided an image into blocks where each block has 8*8 pixels .Now i want to find the energy of each block,for that i have to consider the energy of each pixels in a block and the calculations are given in the code below.

After making the calculation for each block i have to show the enery map of the image that is being divided into blocks ,but i am not geting it .Can you plz help me .Actualy i am trying to do block based seam carving

x=imread('cameraman.tif');
y=double(x);
[r c]=size(y);
bs=8; %size of each block
nob=(r/bs)*(c/bs);%number of blocks

kk=0;
for i=1:(r/bs)
    for j=1:(c/bs)
        Block(:,:,kk+j)=y((bs*(i-1)+1:bs*(i-1)+bs),(bs*(j-1)+1:bs*(j-1)+bs));
%block creation

          %ENERGY CALCULATION PER BLOCK
              for q=1:bs
              for p=1:bs

                  if((q-1==0)&&(p-1==0))
                              a=Block(q,p,kk+j);
                              b=0;
                              n=a-b;
                                  c=Block(q,p,kk+j);
                                  d=0;
                                  m=c-d;

                  elseif((q-1==0)&&(p-1~=0))
                      n=y(q:q,p)-y(q:q,p-1);
                              a=Block(q,p,kk+j);
                              b=0;
                              m=a-b;

                  elseif((q-1~=0)&&(p-1==0))
                     a=Block(q,p,kk+j);
                     b=0;
                     n=a-b;
                               m=y(q:q,p)-y(q-1:q-1,p);

                  else
                       n=y(q:q,p)-y(q:q,p-1);
                               m=y(q:q,p)-y(q-1:q-1,p);

                  end
                       s=n+m ;%  

                      en=s/nob;%Here the calculation for energy for block is being done.
         imshow(en) 
  % Here i want  to show  the energy map for the entier blocks but unfortunatly i am geting only a single spot.

              end

      end

      end

      kk=kk+(r/bs);

end         

         %%%%%%%%%% I GOT UR ANSWER BUT I'M NOT GETING THE CORRECT OUTPUT ,CAN U PLZZZZ HELP ME OUT.THE PBLM THAT I FACED IS PUT AS A COMMENT TO UR ANSWER PLZ CHECK IT..

[Amith Kamath]

at the outset: please read http://www.mathworks.com/matlabcentral/about/answers/# , especially the tips on asking a question, for it's quite hard for people to really understand your actual question..

Thanks!

[yasmine]

please i want to to know can i use ur method of cutting image into blocks for RGB images ?

Thank you

[ROSE MARY KATIKALA]

i want to divide an image into blocks and then calculate energy values for each block.. to make roads and non roads in my project

[ROSE MARY KATIKALA]

can u please help me out.. im new for matlab

[Image Analyst]

What's your definition of energy? If you go back to first principles, and work out the units, you'll see that gray level has units of energy. So all you need to do is to take the moving mean, like in the attached demos.

Answer 1

[Image Analyst]

Is "en" an image? I don't see any indices being used when you set values for it. It looks to me like it is a scalar so that would show up as a single point.

Maybe you want this

en(p, q)=s/nob;

and then after the q and p loops have finished (when you'll have the complete image), do the imshow.

[Soumya]

Sir ,

Firstly I want to make a notification that "en" is the energy of the image and by performing imshow in en I need an energy map figure but I'm not getting it . Now what should I do??????????/////

Thanks & Regards

soumya sadan

[Soumya]

sir,

Is it possible to view the entire blocks using mat2cell()?If so plzz explain?

Is it possible to extract individual blocks from an image which is divided using blkproc()?If so how?

I'm not getting the images divided into blocks so I'm thinking to use blkproc or mat2cell(),but the problem is that I want to show the image divided into blocks and to process on each block......

plzzz give me a reply.........................

[Image Analyst]

Doesn't the imshow(en), with the now fixed en, work to show the image? If not you'll have to add a drawnow after that so that it will force the screen to update.

[Soumya]

sir,

I tried many times but I'm not getting the image divided into blocks.And what do u meant by " to add a drawnow",i can't understand bcozzzz I'm new to this environment .So now I'm thinking to use blkproc or mat2cell,but the problem is that:

1)I have to show the image divided blocks (like that obtained by using blkproc)

2)Take individual blocks and perform some process on each blocks.

can u help me out????????????????/

[Image Analyst]

Tell us exactly what you mean by "divided". Do you want hundred of sub images in their own variables, each with a different variable name, or as a cell in a cell array? Look up drawnow in the help. You simply have the letters "drawnow;" on their own line following the imshow line.

[Soumya]

actually I want to divide the entire pixels of image to 8x8 submatrices or blocks,and display the image which is divided into blocks and also display the individual blocks.Then we want to perform some calculation on individual blocks ie;perform calculation pixel by pixel in a block.

[Image Analyst]

That is what blockproc does. But do you need to keep ALL of the hundreds of submatrices hanging around in memory? I doubt it.

[Soumya]

sir,

I'm using matlab2009 ,so I think blockproc won't work.Can u plzzz correct the above given code,so that I can get the image diveided into no:of blocks,and whenever I call en(num) I should get each block and perform processing on each block

[Soumya]

sir,

Now I'm thinking that the entire blocks is difficult to be displayed in an image,so how would be the idea of arranging the blocks in a different matrix in the correct order,and give different colors to each row,so that I can understand that a particular block belongs to a particular row.

[Walter Roberson]

If your MATLAB does not have blockproc, use blkproc instead. blkproc passes the actual data for the block in to the user routine, not information about the block, so you would not pass in the block number: you would just calculate the energy for the data given and return it and blkproc() will take care of arranging the results in to a matrix in the same shape as the blocks.

[Walter Roberson]

Instead of coloring the rows differently, consider just turning the XGrid and YGrid properties of the axes on, with the XTick and YTick properties set to the boundaries of the blocks.

http://www.mathworks.com/help/techdoc/ref/grid.html

[Soumya]

I'm thinking like this becozzzz on getting a block am not sure that it is the correct matrix from the image.If I'm not getting the correct blocks from the image ,then how could I perform calculation on individual blocks .plzzz help me.

If u don't mind I want to know that is there any way to directly contact with u sir.So that I can give u the correct idea about wat am doing

[Soumya]

sir,

if we are using the blkproc() we can display the image into blocks but how can we access individual blocks (like: on calling a(num) should give each individual blocks within the image)

[Walter Roberson]

You can use mat2cell if you need to break the image up in to separate matrices so that you can be sure that you are getting the correct block or so that you can use indexing to access the block.

[Soumya]

by using mat2cell I don't know how t access more than one vlocks in corect order can u help me?????????????//

[Walter Roberson]

blocks = cell2mat(y, 8 * ones(1,r/8), 8 * ones(1,c/8));

blocks{1,1} %upper left block

blocks{1,2} %block to the right of upper left

blocks{1,3} %block two over from upper left

blocks{2,3} %block below the one two over from upper right

blocks{end,end} %lower right

Or if it is important to be able to index the blocks by a single number, then

blocks{1}

blocks{2}

blocks{3}

and so on, where the block numbers go *down* the first column, then continue from the top of the second column on downwards, then continue from the top of the third column downwards, and so on.

[Soumya]

code:

[x,map]=imread('cameraman.tif');

bw=edge(x,'sobel');

[r c]=size(bw)

blocks = mat2cell(bw, 8 * ones(1,r/8), 8 * ones(1,c/8));

arr=magic(256);

for i=1:256

for j=1:256

arr=blocks{i,j};

end

end

figure,imshow(arr);

/////////////////////

I'm using the above given code.

According to ur instruction I used mat2cell.Here I've decalared an array "arr" of size 256x256 and used two loops. Bcozzz I want to access each block and fix it in the "arr" array so that when I display the entire array I would be able to display the entire blocks with in the array in the correct order as in the image.I have got strict instruction to do this can u help me????????????

But I'm getting an error like

????Index exceeds matrix dimensions.

Error in ==> mat4mat2cell at 12

arr=blocks{i,j};

[Soumya]

code:

[x,map]=imread('cameraman.tif');

bw=edge(x,'sobel');

[r c]=size(bw);

blocks = mat2cell(bw, 8 * ones(1,r/8), 8 * ones(1,c/8));

arr=magic(256);

for i=1:8:256

for j=1:8:256

for r=1:32

for c=1:32

arr(i,j)=blocks{r,c} ;

end

end

end

end

figure,imshow(arr);

//////

Later I tried this code to assign each blocks to the "arr" in the correct order but I'm getting an error:

??? Subscripted assignment dimension mismatch.

Error in ==> mat4mat2cell at 12

arr(i,j)=blocks{r,c} ;

Can u help me by removing this error plzzzzzzz.

[Walter Roberson]

for r=1:size(blocks,1)

for c=1:size(blocks,2)

arr((r-1)*8+1:r*8,(c-1)*8+1:c*8) = blocks{r,c};

end

end

[Soumya]

Sir,

Your code was helpfull for me,but I've a small doubt-----> size(blocks,1)&size(blocks,2)=>> I know that the size is 32 but what's the purpose of mentioning the number 1 and 2.Cant we simply specify it like size(blocks).........

[Image Analyst]

size(blocks,1) gets the the number of rows and size(blocks,2) gets you the number of columns. You can also do it like this if you want

[rows columns] = size(yourArray);

[Soumya]

Now I'm working to find the energy of each block using the equation like: for a pixel (x,y) the calculation is made by

sum=((x,y)-(x-1,y))+((x,y)-(x,y-1))%% calculation made per pixel in a block

energy=1/total numbers of pixels in a block*∑(sum)%%here energy of a block is to be obtained

This is the equation and I tried to implement it but I'm not getting the correct thing.

code----->>

[x,map]=imread('cameraman.tif');

bw=edge(x,'sobel');

[r c]=size(bw);

blocks = mat2cell(bw, 8 * ones(1,r/8), 8 * ones(1,c/8));

arr=magic(256);

for r=1:size(blocks,1)

for c=1:size(blocks,2)

arr((r-1)*8+1:r*8,(c-1)*8+1:c*8) = blocks{r,c};

end

end

figure,imshow(arr);

for r=1:32

for c=1:32

blocks{r,c} ;

for q=1:8 % row in a block

for p=1:8 %col in a block

if((q-1==0)&&(p-1==0)) %%%%%%%%%%%%%%%%%%%%%condition for the top most and left most elements in a block%%%%%%%%%%%%%%%%%%%%%%%%%

a=blocks{r,c}(q,p);

b=0;

n=a-b; %%% n variable indicates column wise calculation

cc=blocks{r,c}(q,p);

d=0;

m=c-d; %%% m variable indicates row wise calculation

elseif((q-1==0)&&(p-1~=0)) %%%%%%%%%%condition for the top most elemnts except the left most elements%%%%%%%%%%%%%%%%%%%%

n=blocks{r,c}(q,p)-blocks{r,c}(q,p-1); %%% n variable indicates column wise calculation

a=blocks{r,c}(q,p);

b=0;

m=a-b; %%% m variable indicates row wise calculation

elseif((q-1~=0)&&(p-1==0)) %%%%%%%%%%condition for the left most elements except the to most elements%%%%%%%%%%%%%%%%%%%%

a=blocks{r,c}(q,p);

b=0;

n=a-b;

m=blocks{r,c}(q,p)-blocks{r,c}(q-1,p);

else

n=blocks{r,c}(q,p)-blocks{r,c}(q,p-1);

m=blocks{r,c}(q,p)-blocks{r,c}(q-1,p);

end

s=n+m ;

en=s/64;

e=en;

end

end

end

end

figure,imshow(e);

//////////////////////

the above given is the code , can u figure out the mistake and help me......................

Thanks 4 ur valuable help sir

[Soumya]

sir I have made a mistake in the above given code .Inorder to get the value I should replace the code "figure,imshow(e);" by fprintf("%f",e) [I hope the correction dat I made is correct],but the problem is that where should I print the value to get the energy for an entire block.And like the previously mentioned "arr" array I have to create another array and assign value of each block to the array

can u help me out!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[Soumya]

sir can u explain in matlab how the decrementation is made in for loop.

for r=1:size(blocks,1)

for c=1:size(blocks,2)

%%%%%%%%this is the incrementation loop I need the reverse of this

end

end

As I'm new to this environment I'm unaware about many things plzzz give me a guidance..........

[Image Analyst]

Replace the last few lines of your code with this and see if that doesn't do it for you:

en=s/64;

e(r, c) = en;

end

end

end

end

% Show the energy map.

figure; % New figure

% Make it big enough to see something.

eBig = imresize(e, [512 512], 'Nearest');

% Display it.

imshow(eBig, []);

[Soumya]

Sir.

I'have an image of size 256x256. Now i want to take the minimum value of the pixel from the last row,and after getting the minimum value I need to take the three neighbouring pixels lying on the previous row of the min valued pixel (of the last row)and find min from them.Then again take the three neighbouring pixels on the prevoius row of the min valued pixel(of the second last row) and find minimum from them .In this manner the calculation goes to the first row,thus Iwill get a path of min values fromthe last row to the first row.Inorder to recognize this path I've to specify the pixels in that path with some color like white.

can u help me!!!!!!!!!!!!

[Image Analyst]

A simple for loop and the min() function would do it for you - it's trivial. However, if you think about it for just a few seconds, you will realize that your proposed method WILL NOT get you the path with the overall minimum sum or average going from bottom to top. I suggest you read up on optimization methods. Browse through Wikipedia and look up topics like A*, Dijkstra, depth-first and breadth-first searches, seam carving, dynamic programming, and that kind of thing. You need to spend about 2 hours of reading up first before you waste several hours programming up a bad solution.

[Soumya]

can u explain the meaning of each component of this loop

[rows cols dim]=size(x);

%sobel operator used to calculate gradient image

Grd=[ -1 -2 -1;

0 0 0;

1 2 1];

% Grd1=[ 0 -1 0; -1 4 -1 ; 0 -1 0];

Emean=zeros(rows,cols);

for i=1:dim

Eh(:,:,i)=conv2(x(:,:,i),Grd,'same');

Ev(:,:,i)=conv2(x(:,:,i),Grd.','same');

E(:,:,i)=abs(Eh(:,:,i))+abs(Ev(:,:,i));

% E(:,:,i)=conv2(X(:,:,i),Grd1,'same');

end

Emean=1/dim*sum(E,3); %finds average gradient image if RGB image

plzzzz

[Soumya]

I have an array en() containing energy value where each array of size 8x8 contains energy value per blockie;en(1:8,1:8)-energy of first block,en(9:16,1:8)and on using imshow(en)-I can display an energy map.

the below given code is performed on pixel by pixel basis.Here x is the gradient image instead of it I want to use en array and use additional code if needed so that I can do on block basis . and assign each block value to a seperate array so that on displaying that array I can get an Image.

SeamImg=zeros(rows,cols);

SeamImg(1,:)=x(1,:);

for i=2:rows

for j=1:cols

if j-1<1

SeamImg(i,j)= x(i,j)+min([SeamImg(i-1,j),SeamImg(i-1,j+1)]);

elseif j+1>cols

SeamImg(i,j)= x(i,j)+min([SeamImg(i-1,j-1),SeamImg(i-1,j)]);

else

SeamImg(i,j)= x(i,j)+min([SeamImg(i-1,j-1),SeamImg(i-1,j),SeamImg(i-1,j+1)]);

end

end

end

Help me out from this trouble sirrrr plzzzzzzzzzzzzz

[Soumya]

sir,

Acoording to ur guidance i have solved many of my problems.thanks for ur guidance and instructions sir.At the last moment i am facing a small problem,but I'm not able to find wat's wrong can u help me .code----->

[r c dim]=size(SeamImg);%%128 128

[SVrow SVcol]=size(SeamVector);%%128 128

for i=1:SVcol

for k=1:dim

for j=1:r

if SeamVector(j,i)==1

cut(j,:,k)=SeamImg(j,2:c,k);

elseif SeamVector(j,i)==c

cut(j,:,k)=SeamImg(j,1:c-1,k);

else

cut(j,:,k)=[SeamImg(j,1:SeamVector(j,i)-1,k) SeamImg(j,SeamVector(j,i)+1:c,k)];

end

end

end

end

SeamImg=cut;

clear cut

figure

imshow(SeamImg)

%%%error-->

Subscripted assignment dimension mismatch.

Error in ==> blocksfinal at 186

cut(j,:,k)=[SeamImg(j,1:SeamVector(j,i)-1,k) SeamImg(j,SeamVector(j,i)+1:c,k)];

I'm waiting for ur valuable instructions......

[Walter Roberson]

That error could occur if you had initialized the cut() array to an incompatible size. You do not _show_ any initialization for cut(), but we don't know that you did not do any in code you did not show us.