I have an image where I divided image matrix into cell array each of size 4*4 using mat2cell().Tell me how to get the coordinates of each selected cell array

I have wriiten the code as follows:

rgbImage = imread('male.jpg');
[rows columns numberOfColorBands] = size(rgbImage);
padimg=padarray(rgbImage,[0 80],'replicate','post');
size(padimg);
[rows1 columns1 numberOfColorBands1] = size(padimg);
blockSizeR = 4; % Rows in block.
blockSizeC = 4;
wholeBlockRows = floor(rows1 / blockSizeR);
blockVectorR = [blockSizeR * ones(1, wholeBlockRows)];
size(blockVectorR);
wholeBlockCols = floor(columns1 / blockSizeC);
blockVectorC = [blockSizeC * ones(1, wholeBlockCols)];
size(blockVectorC);
ca = mat2cell(padimg, blockVectorR, blockVectorC, numberOfColorBands);
%celldisp(ca);
%imshow('padimg')
%ca{40,40}
%ca{1,1}
%[xc,yc,pixval]=impixel(ca{1,1});

here when I use impixel it displays picture to select pixels..instead i need to get all pixel positions of that cell array without selection

Answer 1

[Walter Roberson]

ca{J,K} is image coordinates (J-1)*4+1 : J * 4, (K-1)*4+1 : K * 4

[alapati pujitha]

logic you have given prints the pixel intensities.I require x and y coordinates of each selected cell array

[Walter Roberson]

No, the coordinates are (J-1)*4+1 : J * 4 and (K-1)*4+1 : K * 4, in all combinations. If you need a complete table of them then:

[gridR, gridC] = ndgrid((J-1)*4+1 : J * 4, (K-1)*4+1 : K * 4);
RC = [gridR(:), gridC(:)];

Now RC will be a 16 x 2 matrix of rows and columns.

Note: Rows correspond to Y coordinates, and columns correspond to X coordinates.

If you have an X, Y coordinate system that is not the same as rows and columns, then small adjustments can be made. For example, if Xcoords and Ycoords are the vectors of X coordinates corresponding to each column and Y coordinates corresponding to each row, then

[gridR, gridC] = ndgrid((J-1)*4+1 : J * 4, (K-1)*4+1 : K * 4);
XY = [Xcoords(gridC(:)), Ycords(gridR(:))];

which will be a 16 x 2 matrix of X and Y coordinates.

And not a single pixel intensity involved.