Determine the largest length along the width of the part

I have a binary image

what I want to do is

1. Calculate the sum of black pixels along each and every individual row

2. Then compare the individual sums to get the largest value(which would be my answer).

or in other words

Determine the largest length along the width of the part.

I have another question

>>>>I want to count the number of black pixels in each individual row and then compare that result to get 'which row has highest number of black pixels'.

[Image Analyst]

Your final question was answered by the second comment I gave to my original answer. I give you both the count, AND the row at which that highest count happens at. Isn't that what you want?

Answer 1

[Image Analyst]

% 1. Calculate the sum of black pixels along each and every individual row 
verticalProfile = sum(binaryImage, 2);

% 2. Then compare the individual sums to get the largest value
% (which would be my answer).
[maxWidth, rowAtMaxWidth] = max(verticalProfile);

[Image Analyst]

Sorry - use min() instead of max() if your binary image is the opposite of the normal, which it sounds like your is. Your foreground is black rather than white, as usual. So you'd do

% 1. Calculate the sum of black pixels along each and every individual row 
verticalProfile = sum(binaryImage, 2);

% 2. Then compare the individual sums to get the largest value
% (which would be my answer).
[maxWidth, rowAtMaxWidth] = min(verticalProfile);

[Image Analyst]

If your binary image is the opposite of the normal, which it sounds like yours is. Your foreground is black rather than white, as usual. So to count the black pixels, you'd do

% 1. Calculate the sum of black pixels along each and every individual row 
verticalProfile = sum(~binaryImage, 2);

% 2. Then compare the individual sums to get the largest value
% (which would be my answer).
[numberOfBlackPixels, rowAtMaxWidth] = max(verticalProfile);

Answer 2

[Youssef Khmou]

hi you can try as the following :

I=imread('circuit.tif'); % esample
B=im2bw(I);

S=sum(B);
figure, plot(S),
[y,x]=max(S)
%  X= 252 in this case so the row 252 is the largest