A method for measuring the position of discharging billet in heating furnace based on image recognition

According to the characteristics of the noise of discharging billet, method based on scale product using wavelet transform for denoising is introduced in this thesis. Then evaluation criteria based on edge detection which evaluates the quality of image denoising is proposed, according to the requirements of captured pictures in the thesis. With the position of slab changing in image, gray of edge is changing. So it is unsuitable to detect edge by the fixed threshold value. Therefore, in order to improve image contrast between slab edge and background, image enhancement based on wavelet transform is adopted. Then, the slab edge is detected by Canny operator. After that using Hough transform extract complete and smooth edges of slab. In image, the size of slab is known. Taking advantage of reconstructed image, the relationship of pixel and actual size is assured. At last we can calculate the real position of the slab in reheating furnace.