Posted May 26, 2020
Today we will learn how to detect lines and circles in an image, with the help of a technique called Hough transform.
Before we start applying Hough transform to images, we need to understand what a Hough space is, and we will learn that in the way of an example.
When we work with images, we can imagine the image being a 2d matrix over some x and y coordinates, under which a line could be described as y = mx + b
But in parameter space, which we will call Hough space, I can represent that same line as m
vs b
instead, so the characterization of a line on image space, will be a single point at the position m-b
in Hough space.
But we have a problem though, with y = mx + b
, we cannot represent a vertical line, as the slope is infinite. So we need a better way parametrization, polar coordinates (rho and theta).
#opencv #python