Specifications

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Loss of resolution
Resolution may be lost by any one or combination of the following factors:
1. During capture of the picture information by the camera and electronic processing of
the fresh video signal,
2. In the process of storing the picture information on disk or tape, or transmitting it over
the air on via satellite or "cable",
3. During playback, in the TV set, also in VCR and disk player electronics.
Aspect Ratio
The aspect ratio of an image is its displayed width divided by its height (usually
expressed as "x:y" or "x×y," with the joining colon or multiplication symbol articulated as
the preposition "by" or sometimes "to"). For instance, the aspect ratio of a traditional
television screen is 4:3, or 1.33:1. High Definition Television and European digital
television use an aspect of 16:9, or about 1.78:1.
Quick Description of Vertical and Horizontal Resolution
The more scan lines we have, the better the vertical resolution is possible. That is, the
more dots in a column, or thin lines lying flat in a stack, can be reproduced and
distinguished. When portions of several scan lines in a row are the same at a particular
place on the screen we are reproducing coarse detail. When adjacent scan lines differ, we
are reproducing fine vertical detail. Since each video standard has a fixed number of scan
lines (525 for NTSC, 625 for PAL), vertical resolution is the same for all TV sets of the
same standard except the poorest quality, defective, or very small sets.
Advertised resolution is the horizontal resolution and it varies with the quality of the TV
set. Side by side thin upright lines, whose cross section is a row of dots, are used to
measure horizontal resolution. To resolve horizontal detail, the electron beam changes to
make dots (and dashes) of different colors, along each scan line. The finer the detail we
need to reproduce, the tinier a spot the electron beam must be able to make.