Function imageproc::contours::find_contours_with_threshold

pub fn find_contours_with_threshold<T>(
    image: &GrayImage, 
    threshold: u8
) -> Vec<Contour<T>> where
    T: Num + NumCast + Copy + PartialEq + Eq, 

Finds all borders of foreground regions in an image. All pixels with intensity strictly greater than threshold are treated as belonging to the foreground.

Based on the algorithm proposed by Suzuki and Abe: Topological Structural Analysis of Digitized Binary Images by Border Following.