Image and Vision Computing, Vol. 18, No. 8, pp. 607-618, 2000
This paper proposes a gray-scale inverse Hough transform (GIHT) algorithm which is combined with a modified gray-scale Hough transform (GHT). Given only the data of the Hough transform (HT) space and the dimensions of the image, the GIHT algorithm reconstructs correctly the original gray-scale image. As a first application, the GIHT is used for line detection and filtering according to conditions associated with the polar parameters, the size and the gray-scale values of the lines. The main advantage of the GIHT is the determination of the image lines exactly as they appear, i.e. pixel by pixel and with the correct gray-scale values. To avoid the quantization effects in the accumulator array of the GHT space, inversion conditions are defined which are associated only with the image size. The GIHT algorithm consists of two phases, which are the collection of gray-scale information stored in the accumulator array and the extraction of the final image according to the filtering conditions. Experimental results confirm the efficiency of the proposed method.