After the image is represented in the HSV color space,
a threshold of Hlow = 20
360, Hhigh = 335 360, Slow = 0.3 is
used to detect the red background of the runway holding
position signs. To prevent the algorithm from picking up
random objects of red color, it is required that at least 1000
pixels are detected as red to be considered a valid sign. Then, a
rectangle covering only the sign would be generated cropping
the input image for recognition.