doubt in specific line

img_filt_up = img_filt(1:floor(img_h/2),:);
[~, y_up] = max(img_filt_up); 

% Lower part of filtred image
img_filt_lo = img_filt(half_img_h:end,:);
[~,y_lo] = min(img_filt_lo);

Could you please explain the following line

region(y_up(i):y_lo(i)+size(img_filt_lo,1), i) = 1;

Answer 1

[Arthur Roué]

The line is settings to 1 elements of matrix region from row y_up(i) to row y_lo(i)+size(img_filt_lo,1) in column i.

I suppose i is your index in a for loop, but it would be simpler to answer with a bit of context .

[Rd]

i cant understand the following

size(img_filt_lo,1)

could you explain what 1 represent

[Arthur Roué]

The function size returns a row vector whose elements are the lengths of the corresponding dimensions.

For instance,

% m is a 2 x 3 matrix
m = [1, 1, 1;
     2, 2 ,2]
size(m)
ans =
     2     3

When calling size with a second argument, you get the number of element of the specific dimension

size(m,1)
>> 2
size(m,2)
>> 3

In Matlab, rows are dimension 1 and column dimension 2.

% Return the number element in 1st dimension (row) of img_filt_lo
size(img_filt_lo,1)

[Rd]

i understood.Thank you for your brief explanation.