Help to understand Matlab code

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,

Answer 1

[jonas]

[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

[Matlab Student]

Thanks Jonas.

What about length(size(im))? Does length(size(im)) equals to 2 if im is a two dimensional array, and equals to 3 if im is an image with Height Width and Depth?

[jonas]

My pleasure! Yep, thats correct.