MATLAB: Help to understand Matlab code

digital image processing

Hello Matlab Experts,
I am trying to understand this Matlab code, I am stuck at few lines:
% get resolution and number of band
[m n ~]=size(im);
if length(size(im))==3
    b=size(im,3);
else
    b=1;
end
[m n ~] = size(im) I know size(im) should return the height and width of an image, but what does ~ mean? I have reviewed size documentation but did not find the answer: https://www.mathworks.com/help/matlab/ref/size.html
Also, I need assistance to understand these two lines as well. As per Matlab documentation, szdim = size(A,dim) returns the length of dimension dim. Does this mean size(im,3) return the depth of image pixels?
if length(size(im))==3
    b=size(im,3);
Thanks in advance,

Best Answer

[m n ~] = size(im)
~ basically means "omit this output", and is totally useless in this context. It is useful in other cases, for example if you're only interested in the second output.
[~,out] = func(...)
"Does this mean size(im,3) return the depth of image pixels?"
yes
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