MATLAB: Is this code creating a matrix for the image or is it doing something else

3d image3d imagesImage Processing Toolboxmatrixmatrix array

What exactly are these 3 lines doing?

im2(:,:,1)=im1;
im2(:,:,2)=im1;
im2(:,:,3)=im1;

Best Answer

They're creating a 3D matrix where every slice/channel/plane is the same - it's im1. So im2 can either be a color image that appears as grayscale because all 3 color channels are identical, or it can be a volumetric image (like a CT or MRI image) where all three slices/planes are the same, like you extruded the im1 image upwards.

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MATLAB: If… then… else

Try this solution:

A = [97 100 93 89 86 80 93 94 95 92 80];
% Preallocate
Out  = ones(size(A));
% First element is momentarily the maximum
maxA = A(1);
% Positive sequence
pos  = true;
% Tolerance of 10%
x    = .1;
% Start from the second element (since the first is considered the max)
for ii = 2:numel(A)
    % 1
    if pos
        % If new maximum
        if A(ii) > maxA
            maxA = A(ii);
        % If threshold is broken downwards
        elseif A(ii)/maxA-1 < -x
            minA    = A(ii);
            Out(ii) = -1;
            pos     = false;
        end
    % -1    
    else
        Out(ii) = -1;
        % If new minimum
        if A(ii) < minA
            minA = A(ii);
        % If threshold is broken upwards
        elseif A(ii)/minA-1 > x
            maxA    = A(ii);
            Out(ii) = 1;
            pos     = true;
        end
    end
end

MATLAB: MOD bug? Or something else

Floating point arithmetic.... Look closely at the numbers.

x = [-2:.2:2];
fprintf('%16.16f\n',x)

You can read more about it here.

Best Answer

Related Solutions

MATLAB: If… then… else

MATLAB: MOD bug? Or something else

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