Simultaneous unidirectional and bidirectional chaos-based optical communication using hybrid coupling semiconductor lasers

We propose an intermediate computational step, frequency domain filtering of gradient image, to improve contour detection performance of gradient-based edge detectors. This step is inspired by analyzing the spectrum distribution of object contours and texture edges in the frequency domain of gradient image. We illustrate the principle and effect of this step by adding it to the Canny edge detector. The resulting operator can selectively retain object contours and region boundaries, and meanwhile can dramatically reduce non-meaningful elements caused by textured background. We use several types of images to compare the proposed method and other related methods qualitatively and quantitatively. Experimental results show that the proposed method can effectively enhance the contour detection of Canny edge detector and achieves similar detection performance to two other related methods but runs faster.