## help with edge processing in an image.

on 19 Dec 2012

### Image Analyst (view profile)

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);
```

## Products

### Image Analyst (view profile)

on 20 Dec 2012

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.

### mounim (view profile)

on 20 Dec 2012

MATLAB and Simulink resources for Arduino, LEGO, and Raspberry Pi