Fully digital auto-focusing system with automatic focusing region selection and point spread function estimation

We present a fully digital auto-focusing (FDAF) system with automatic focusing region selection and a priori estimated dataset of circularly symmetric point-spread functions (PSFs). The proposed approach provides realistic, unsupervised PSF estimation by analyzing the entropy and edge information in the automatically selected focusing region. The main advantage of the proposed system is the fast and robust estimation of a defocusing PSF due to simply selecting the optimal PSF in small, homogeneous region-ofinterest. The proposed FDAF system consists of functional units; i) focusing region selection, ii) PSF selection by generating the major step response in the region from the blurred input image, and iii) image restoration using the selected PSF. Experimental results show the proposed focusing region selection method is more effective than the traditional methods, and the resulting image of the FDAF system provides high visual quality with appropriately amplified details in the image. For this reason, the proposed algorithm can realize low-cost, intelligent focusing function for various image acquisition devices, such as digital cameras, mobile phone cameras, and consumer´s camcorders.