In a television system, what is the ratio between vertical resolution and horizontal scan lines called?

The ratio between vertical resolution and horizontal scan lines in a television system is known as the Kell factor. This term is used to quantify the effective resolution in terms of how many lines are actually displayed on the screen versus the theoretical maximum that could be resolved.

The Kell factor accounts for various distortions and losses that occur in the scanning process, such as the interplay between the horizontal and vertical scanning lines. It reflects the quality of both the display and the imaging technology, giving a more accurate representation of visual performance than simply counting lines.

The other terms, while relevant in specific contexts, do not specifically denote the relationship between vertical resolution and horizontal scan lines. For instance, the line rate factor often refers to the speed of the scan lines and the conversion factor can relate to different forms of signal conversion, but neither captures the specific resolution ratio that the Kell factor does. The resolution factor is a more general term and may relate to various types of resolutions but does not specifically describe the ratio of vertical to horizontal lines in television systems as the Kell factor does.