<title>Geometrical noise bandwidth: a new tool to characterize the resolving power of analogue and digital imaging devices</title>

Abstract

The electrical noise bandwidth quantifies the transfer of noise in electrical systems. Geometrically, the noise can be interpreted as a circle of confusion. The adaptation of the electrical noise bandwidth to geometrical resolution problems demands a generalization of frequencies in two dimensions. The Geometrical Noise Bandwidth is calculated from the product of all MTF, which give the final picture. Here, the optics, the pixel form and size, the color interpolation and optical low pass filters can be considered. Geometrical Noise Bandwidth is measured in mm<SUP>-2</SUP>. It can be calculated by integration for films. In the case of digital imaging devices, the integration limit of spatial frequencies is the Nyquist frequency. The circle of confusion is inverse proportional to the quadratic root of the Geometrical Noise Bandwidth. The results of different imaging devices (photographic film, classical monochrome and color matrices, Fuji Super CCD, several digital-backs, scanners) will be compared using test- pictures of the Siemens star resolution test target. Beyond this, the Geometrical Noise Bandwidth permits comparison of the information contents of classical films and digital matrices. We obtain information to evaluate whether digital imaging devices are better than photographic films.