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Asked by mounim
on 19 Dec 2012

HeY everyone

i hope someone can help me with a project, what i am trying to do is calculating the angle between 2 bones. I already got some help with drawing the axis of the bones from this forum. but as you can see, in the the bottom part i have 2 bones, what can do to only get the axis through the thicker bone ( i only want to define the edge of the thicker bone )? anyhelp will be appreciated, thanks

clc; close all; imtool close all; clear; fontSize = 20;

grayImage = imread('6.jpg'); % Get the dimensions of the image. % numberOfColorBands should be = 1. [rows columns numberOfColorBands] = size(grayImage) % Convert to grayscale if numberOfColorBands > 1 grayImage = grayImage(:, :, 2); end % Crop away white boundary %grayImage = grayImage(1:840, 1:450); % Binarize the image binaryImage = grayImage > 128; % Display the original gray scale image. % subplot(2, 2, 1); imshow(grayImage, []);

% for loop to define the range of interest for the bone 1 for k=30:100

oneRow = binaryImage(k, :);

leftEdge = find(oneRow, 1, 'first'); rightEdge = find(oneRow, 1, 'last');

hold on;

midpoints(k) = (leftEdge + rightEdge)/2;

plot(leftEdge, k, 'rx','LineWidth',2); plot(rightEdge, k, 'rx','LineWidth',2)

plot(midpoints(k), k, 'yx','LineWidth',2);

end

X=(30:100); midpoints=midpoints(midpoints~=0); new_x = linspace(1, 400); coeffs = polyfit(X, midpoints, 1); new_y = polyval(coeffs, new_x); plot(new_y,new_x, '-','LineWidth',2);

% for loop to define the range of interest for the bone 1 for i=700:800

oneRow1 = binaryImage(i, :);

leftEdge1 = find(oneRow1, 1, 'first'); rightEdge1 = find(oneRow1, 1, 'last');

hold on;

if isempty(leftEdge1) midpoint1(i) = 0; else midpoints1(i) = (leftEdge1 + rightEdge1)/2;

plot(leftEdge1, i, 'rx','LineWidth',2); plot(rightEdge1, i, 'rx','LineWidth',2);

plot(midpoints1(i), i, 'yx','LineWidth',2); end end

X1=(700:800); midpoints1=midpoints1(midpoints1~=0); new_x1 = linspace(500, 900); coeffs1 = polyfit(X1, midpoints1, 1); new_y1 = polyval(coeffs1, new_x1); plot(new_y1,new_x1, '-','LineWidth',2);

Femur = abs(atand(coeffs(1))); Tibia = abs(atand(coeffs1(1)));

Angle = Femur + Tibia;

title(Angle , 'FontSize', fontSize);

Answer by Image Analyst
on 20 Dec 2012

Accepted answer

You have to threshold the lower part of your image to detect the bones. Then scan each line and determine if there are two big sections, or just one. If there are two, take just the biggest one.

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