Image Gradation, Graininess and Sharpness in Television and Motion-Picture Systems: Part III: The Grain Structure of Television Images

The analysis of grain structures in imaging systems containing a point- or line-raster process requires evaluation of the sine-wave response in two coordinates. The characteristics of the raster process are developed by a Fourier analysis of the optical image. The sine-wave response perpendicular to the raster lines (for example the vertical sine-wave response of a television system) is shown to contain in general a carrier wave, the normal aperture response to sine-wave test signals, and a series of sum-and-difference components with magnitudes depending on the aperture response products of the analyzing and synthesizing apertures preceding and following the raster process (camera tube and kinescope in television systems). A graphic representation of the raster equation (Fig. 70) shows at B glance the number and magnitude of the sine-wave components for any combination of apertures used with the raster process. The application of the aperture theory developed in Part II yields an equivalent optimal aperture (Fig. 80) and equivalent passband (Eq. (64)) for the theoretical television channel. The evaluation of the horizontal sine-wave response of electro-optical systems containing electrical and optical elements is simplified by establishing normalized characteristics for the sine-wave response, equivalent passband, aperture cross section, and edge transition of a variety of electrical response characteristics (including aperture correction) in cascade with optical apertures. Because of their general character and use in the evaluation and design of television systems, the range of parameters has been extended beyond the cases used in examples.

Print ISSN

0898-042X

Published

1953-08

Content type

Original Research

DOI

10.5594/J04909