Curve detection using matlab

Hello, I have the following image:

And im trying to find the line that goes trough the center of the red line, like this:

Any suggestions?

Answer 1

[Stephan]

here is an approach with only using Matlab basic functions:

% Open image file
I = imread('image.jpeg');

% Use Green channel for further opearations
I = I(:,:,2);

% Binarize Image
I(I>20) = 255;
I(I~=255) = 0;

% Preallocate vector of line middle coordinates  
mid = 255*ones(size(I,1),1);

% loop through and find the mid of every single line
% and make a white dot at the middle position
for k = 1:numel(mid)
    mid(k) = floor(median(find(I(k,:)==0)));
    try
        I(k,mid(k)) = 255;
    catch
    end
end

% show image
imshow(I)

The cordinates of the middle line are saved in mid and are NaN at all lines where no line exists-

Edit:

We can also do this without a for loop:

% Open image file
I = imread('image.jpeg');

% Use Green channel for further opearations
I = I(:,:,2);

% Binarize Image
I(I>20) = 255;
I(I~=255) = 0;

% remove content without line
I(255*size(I,2) == sum(I,2),:) = [];

% find black pixels
[r,c] = find(I==0);

% find mid in x-direction
Gx = findgroups(r);
mid_x = sub2ind([size(I,1), size(I,2)], (1:size(I,1))', floor(splitapply(@median,c,r)));

% mark the mid-line white
I(mid_x) = 255;

% show image
imshow(I)

[Joseph Cybul]

Thanks a lot for the quick anwser it worked very well!!