High-resolution digital zooming using a fisheye lens and geometric compensation

Abstract

A computational camera uses unconventional optics and digital signal processing software to produce new forms of visual information [1]. This paper presents a computational ca mera approach to near-lossless, high-quality digital zooming using a fisheye lens. Conventional digital zooming systems employed in compact consumer's imaging devices result in severe distortions in output images due to the limited amount of information. In spite of such lim ited quality, the digital z ooming function is e quipped in many inexpensive cameras because of its desirable properties, such as compactness, low power consumption, and low cost. In order to overcome the limited quality of the conventional digital zooming system, we use a fisheye lens with appropriate digital image processing algorithms. For realization of the proposed computational camera-based digital zooming, we fir stge nerate input test images using a commercial optical simulator. We then calibrate the fisheye lens using a special rectangular grid patterns. Finally, we remove the barrel distortion in the output of the fisheye lens, and crop an appropriate size of rectangular region in the center. Experimental results indicate that the proposed computational camera-based digital zooming system can significantly increase the resolution of output images compared with conventional digital zooming systems, especially at magnification ratio of 3 or higher.