Estimation of Image Magnification Change Using Hough Transform

Many cameras change in the image-magnification for every change in focus position. The change in the image-magnification becomes an obstacle in the depth from focus (DFF) method. Therefore, in this paper, we propose a method for automatically estimating the image-magnification change rate. The DFF method is applied after compensating for change in the image-magnification. In this method, an image is changed by altering the focus position of the edge strength on the straight lines in the taken image. The rate of change is estimated from the slope of the straight lines detected. This paper examined the effectiveness of this method with respect to the compensation degree of change in the image magnification.