i've divided the image into non-overlapping blocks and i want to calculate the mean of every block...

after calculating the mean i;ve to store it in array corresponding to their block number

plz tell me how to do?

Mean=[];

for row = 1 : blockSizeR : rows
   for col = 1 : blockSizeC : columns

                row1 = row;
    row2 = row1 + blockSizeR - 1;
    row2 = min(rows, row2);
                col1 = col;
    col2 = col1 + blockSizeC - 1;
    col2 = min(columns, col2);
                oneBlock = grayImage(row1:row2, col1:col2);
                m=mean(mean(oneBlock));
                M=m;
                Mean=[Mean;M];
                disp(Mean);
           end
     end

the above code shows only the mean value... but i want that it also shows the block number corresponding to the mean value...

plz rectify or modify the above code in order to do so.

Answer 1

[Image Analyst]

Not sure how you want to define block number but how about:

blockNumber = 1;
for row = 1 : blockSizeR : rows
   for col = 1 : blockSizeC : columns
                row1 = row;
    row2 = row1 + blockSizeR - 1;
    row2 = min(rows, row2);
                col1 = col;
    col2 = col1 + blockSizeC - 1;
    col2 = min(columns, col2);
                oneBlock = grayImage(row1:row2, col1:col2);
                Mean(blockNumber) = mean2(oneBlock);
                fprintf('The mean for block #%d = $f', ...
                blockNumber, Mean(blockNumber));
                blockNumber = blockNumber + 1;
    end
end

[angel]

thank u sir....it works as i wanted...now i m trying to sort the mean values...m applying the sort function....i want output in the form as:

mean of block 1 =12.34

mean of block 2= 6.78

mean of block 3= 34.56

mean of block 4=3.56

after applying sort function i want this to be as:

mean of block 4 =3.56

mean of block 2 = 6.78

mean of block 1 = 12.34

mean of block 3 = 34.56

[angel]

 blockNumber = 1;

 for row = 1 : blockSizeR : rows

   for col = 1 : blockSizeC : columns
                row1 = row;
    row2 = row1 + blockSizeR - 1;
    row2 = min(rows, row2);
                col1 = col;
    col2 = col1 + blockSizeC - 1;
    col2 = min(columns, col2);
                oneBlock = grayImage(row1:row2, col1:col2);
                Mean(blockNumber) = mean2(oneBlock);
                fprintf('The mean for block #%d = $f', ...
                blockNumber, Mean(blockNumber));
                blockNumber = blockNumber + 1;
    end
end

 S=sort(Mean);

 fprintf('\nBlock # %d = %f',blockNumber,S);

but output is not as per i want... help me sir...

[Image Analyst]

You have to take both return arguments of sort(), not just one.

[angel]

can u code it sir for me plz.... u mean

 S=sort(Mean(blockNumber);
 fprintf('\nblock #%d = %f',blockNumber,S);

if not, correct it plz

[Walter Roberson]

[S, blockNumber] = sort(Mean);
fprintf('\nBlock #%d = %f', [blockNumber(:), S(:)].' );

[angel]

thank u so much sir :)

ur help means a lot to me.

Answer 2

[Abbas Cheddad]

Hi there,

You could do the following:

%%%%%%%%%%%%%

fun = @(block_struct) mean2(block_struct.data);

I2 = blockproc(A,[8 8],fun);

Block_Mean(:,1)=reshape(I2,[1 size(I2,1)*size(I2,2)]);

Block_Mean(:,2)=1:length(Block_Mean);

%%%%%%%%%%%%%%

Where "A" denotes your image and [8 8] is the size of the block of your choice. This will result in "Block_Mean" which holds the mean intensity and the corresponding block number.

[angel]

@ Abbas: ya sir but block_proc returns single image after processing all the blocks..i've given the code above i have modified it as the image anaylst told me... i m trying to applying the sort function but not stricking to me how to apply

[Abbas Cheddad]

Block_proc returns a single image with the same size as "A" if you use the documented code as in:

fun = @(block_struct) ...
   mean2(block_struct.data) * ones(size(block_struct.data));

But in the code I have given you, each pixel in "I2" corresponds to the mean of a single block.

Anyhow, since what you have in hand works for you then happy days!

Answer 3

[Jan]

The fast C-MEX function FEX: BlockMean performs this operation.

R = BlockMean(img, blockSizeR, blockSizeC);

[angel]

this shows error:

Undefined function 'BlockMean' for input arguments of type 'uint8'. input image is 256 x 256

sir plz help me in sorting the mean values which i've calculated...

plz go through the above code that i've mentioned and tell me..

[Walter Roberson]

You need to download and install that code in order to have a BlockMean routine.

[angel]

ok sir :)

regards Angel