is there a way so that we extract a particular block from an 8x8 image?

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Raman 2013-3-10

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/66547-is-there-a-way-so-that-we-extract-a-particular-block-from-an-8x8-image

采纳的回答： Walter Roberson

在 MATLAB Online 中打开

i've an image of size 8x8 blocks i.e total of 64 blocks.

i want to extract or show only few blocks...

how can i do so?

 for row = 1 : blockSizeR : rows
  for col = 1 : blockSizeC : columns
    row1 = row;
    row2 = row1 + blockSizeR - 1;
    row2 = min(rows, row2);

% Determine starting and ending columns.

                 col1 = col;
                 col2 = col1 + blockSizeC - 1;
                 col2 = min(columns, col2);

% Extract out the block into a single subimage.

                 oneBlock = grayImage(row1:row2, col1:col2);
               % Specify the location for display of the image.
    subplot(6,8, blockNumber);
    imshow(oneBlock);
         end 
  end

the above code shows all the 64 blocks..

what should i do, so that only block 10 and block 34 is show rather than all the blocks..

if there is a way tell me how to do it..

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Raman 2013-3-11

编辑：Raman 2013-3-11

how can can i do so? can u help me sir by writing few lines of code plz..

reply plz

Raman 2013-3-12

can anyone help me plz....

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采纳的回答

Walter Roberson 2013-3-12

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/66547-is-there-a-way-so-that-we-extract-a-particular-block-from-an-8x8-image#answer_78271

编辑：Walter Roberson 2013-3-12

在 MATLAB Online 中打开

blockrows =8; blockcols = 8;
[blockcol, blockcol] = ind2sub( [blockcols, blockrows], BlockNumber]
colstart = (blockcol-1) * blockSizeC + 1;
rowstart = (blockrow - 1) * blockSizeR + 1;
oneBlock = grayImage(rowstart : rowstart + blockSizeR - 1, colstart : colstart + blockSizeC - 1);

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Walter Roberson 2013-3-12

Sorry, should have been ind2sub() rather than idx2subs()

Do not enclose this in a "for" loop. The above is the complete code to extract by block number. For example to extract block #34, use those lines of code with BlockNumber = 34

Raman 2013-3-12