GRAY-SCALE HOUGH TRANSFORM FOR THICK LINE DETECTION IN GRAY-SCALE IMAGES

A new extension of the Hough transform, called gray-scale Hough transform (GSHT), is proposed for detecting thick lines (called bands) in a gray-scale image. The use of the conventional Hough transform (CHT) usually requires the preprocessing steps of thresholding and edge detection (or thinning) before the transform can be performed on a gray-scale image containing bands. This causes loss of useful gray and position relationship existing among the pixels of a band, and requires certain postprocessing steps to recover the band in the original image. The proposed GSHT with a gray-scale image as the direct input removes this shortcoming, requiring neither preprocessing nor postprocessing step in detecting bands in a gray-scale image. Experimental results, showing the feasibility of the proposed approach, are also included.