A simple and effective automatic focusing algorithm is proposed in this article. The principle of the proposed automatic focusing algorithm is based on that, for the radial test pattern, a best-focused image should have the smallest blurred region in the middle of the acquired image, and hence, should have the smallest equivalent radius. The circular Hough transform has became a common method i...

The Circle Hough Transform (CHT) has become a common method for circle detection in numerous image processing applications. Because of its drawbacks, various modifications to the basic CHT method have been suggested. This paper presents an algorithm to find circles which are totally brighter or darker than their backgrounds. The method is size-invariant, and such circular shapes can be found ve...

The main drawbacks of the Hough transform (HT) are the heavy requirement of computation and storage. To improve the drawbacks of the HT, the randomized Hough transform (RHT) was proposed. But the RHT is not suitable for detecting the pattern with the complex image because the probability is too low. In this paper, we propose a fast randomized Hough transform for circle/circular arc detection. W...

The problem of road sign detection and recognition is very important in many practical problems, above all for road cadastral authorities. In this sense, an automatic application able to identify the kind of a road sign starting from common imageries such as photos could be very helpful. The main difficulty is due to a possible poor graphical definition of the imagery. In this case, a valid sup...

In this paper we present a new method for coin identification. The proposed method adopts a hybrid scheme using Eigenvalues of covariance matrix, Circular Hough Transform (CHT) and Bresenham’s circle algorithm. The statistical and geometrical properties of the small and large Eigenvalues of the covariance matrix of a set of edge pixels over a connected region of support are explored for the pur...

In this paper we present a method based on the fuzzy Hough transform to locate the iliac crests in posteroanterior radiographs. Firstly, a Canny edge detector is applied to the X-ray images in order to obtain an edge map. Then, the fuzzy Hough transform is used in combination with several constraints extracted from our domain knowledge. At the bottom of the radiograph we search for two circular...