How can I find the length in a binary image?

Hi. I'd like to calculate the average length of the redline that I drew.

Red lines are representing the longest length (in vertical-wise) of the each objects.

The original images are already in binary images

Answer 1

[Image Analyst]

It looks like it goes from the first white pixel in two different columns down to the bottom of the image, which is just the sum of the white pixels in the whole column.

length1 = nnz(binaryImage(:, column1))
length2 = nnz(binaryImage(:, column2))
averageLength = (length1 + length2) / 2