Extracting distance from defocused images with different aperture sizes

✍ Scribed by Masahiko Iwane

• Book ID: 104591530
• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 840 KB
• Volume: 23
• Category: Article
• ISSN: 0882-1666
• DOI: 10.1002/scj.4690231007

✦ Synopsis

Abstract

Using a geometrical optics model, a method is derived for estimating distance from two images with blur due to defocus aberration taken under different conditions of aperture sizes in general illumination to an object.

First, it is shown that the Fourier spectrum of geometrical optics spatial frequency characteristics can be approximated by Gaussian‐type functions.

Next, the relationship between radii of blur circles and Gaussian‐type functions is clarified. It is shown that the ratio of Fourier spectra of two defocused images depends only on the radii of blur circles and that the distance to the object can be estimated by estimating blur spreading radii from two defocused images by the least‐square method. Experiments were conducted using commercially available equipment. Distance errors within 9 percent were obtained in the cases of defocused images with F = 1.4 and F = 2.8 and of about 4 percent in the cases of defocused images of general scenes with F = 2 and F = 4. Thus, the effectiveness of this method was shown.