GRIDBLK - Tiling of an image.

Contents

Description

Given an input image or the vector of its dimensions, compute the coordinates of the centers and the size of the square blocks dividing the image in a given number of regular tiles.

Syntax

   [C,S] = GRIDBLK(I, nb);

Inputs

I : image or vector of dimensions.

nb : upper bound for the total number of desired blocks dividing the image regularly.

Outputs

C : vector of coordinates of the centers of the tiling blocks.

S : vector of dimensions of the tiling blocks.

See also

Ressembles: BESTBLK. Requires: MESHGRID.

Function implementation

function [C,S] = gridblk(I, nb)

XY = size(I(:,:,1));

if any(XY==ones(size(XY)))
    X = I(1);  Y = I(2);
else
    X = XY(1);  Y = XY(2);
end

S = sqrt(X* Y)/floor(sqrt(nb)); % nb will be an upper bound
% S = sqrt(X* Y/nb); % nb will be a lower bound

compute the coordinates in x and y direction respectively

if true  % isempty(ver('images'))
    x = floor(X / S);
    if S*x<X,  x = x+1;  end
    if x==0,  x = floor(X/2);
    else      x = floor(S * (0:x-1) + S/2);
    end
    x(end) = min([X x(end)]);

    y = floor(Y / S);
    if S*y<Y,  y = y +1;  end
    if y==0,  y = floor(X/2);
    else      y = floor(S * (0:y-1) + S/2);
    end
    y(end) = min([Y y(end)]);
    S = [S S];

else
    sb = bestblk([X Y], S);                                            %#ok
    x = floor(S/2:sb(1):X);
    y = floor(S/2:sb(2):Y);
    S = [sb(1) sb(2)];
end

'grid'

[x y] = meshgrid(x, y);

final vector of coordinates

C = [x(:) y(:)];

end % end of gridblk