Detect the edge and mesaure the distance measurement of jet?

Hi, i have high speed images of a jet, now i need to measure its penetration. Since i am a beginner with matlab therefore needed help to measure it. There is a jet with an angle. I need to detect the jet edge and to measure it distance (horizontal) from the origin.

    % code clear all
mmPerPixel = 0.101;
Img=imread('C00018.tif');
[rows, columns, numberOfColorChannels] = size(Img);
pixelsPermm = 25 / mmPerPixel;
x1 = 15; % Starting column.
x2 = x1 + pixelsPermm;
y = round(0.9 * rows);
edge_r=edge(Img,'Roberts');
figure(1);imshow(Img, [0 2500]);
figure(2); imshow(edge_r);
line([x1, x2], [y, y], 'Color', 'r', 'LineWidth', 3);
text(x1, y-20, '25 cm', 'Color', 'r', 'FontSize', 20);

after using the code, i can see the horizontal length of the jet but i dont have its numerical value. I need to measure it till the edge. Needed help with detection. I dont know much about the edge command and its value. or may be i am using the wrong function. Help will be really appreciated.

Answer 1

[Dimitris Iliou]

There is a relevant MATLAB Answers post that might be of help. It talks about finding the length of an object in an image.

https://www.mathworks.com/matlabcentral/answers/163290-how-to-find-the-length-of-an-object-in-an-image