A robust and accumulator-free ellipse hough transform

Abstract

The ellipse Hough transform (EHT) is a widely-used technique. Most of the previous modifications to the standard EHT improved either the voting procedure that computes the absolute measure function (AMF) or the peak detection of the AMF. However, existing EHTs are not robust for detecting partial slightly-oblique ellipses. This paper presents a Robust and Accumulator-Free Ellipse Hough Transform (RAF-EHT), an improved EHT that is robust even for partial slightly-oblique ellipses. Our RAF-EHT is based on two main ideas, namely, (1) an improved measure function (IMF) for handling the partiality and the obliqueness of ellipses, (2) a new accumulator-free computation scheme for finding the top k peaks of the IMF, without complex peak detection. Experimental results show that the RAF-EHT is more robust than the existing EHTs in detecting the partial slightly-oblique ellipses. In addition, the RAF-EHT needs only a little memory because it is accumulator-free.