Image Processing Reference
In-Depth Information
E
Video Raster Sizes
E.1
Summary of Nominal Characteristics
Table E-1 is a summary of the nominal characteristics of some popular video formats.
A few of these are included for historical reasons and others are in the process of being
introduced.
Some estimates of pixel resolution are offered, and these are based on best possible
quality. Your resolvable detail could be lower than some of these values. Define a baseline
around your own system and your observed quality in order to compute the exact storage
capacities. It is OK to overestimate the storage required, and these figures should be accu-
rate enough for most capacity-planning needs.
Note:
Although PAL is noted as having 576 lines, some documents state that it has 574.
You should inspect your source material to establish which it is. If necessary, add
or crop pairs of lines at the top and bottom to adjust to your requirements.
●
Interlaced services have a half line at the bottom of each field in order to reposi-
tion the next scan in between the lines of the previous one. That may explain the
missing 2 lines, since 576-line rasters could be constructed from 574 full lines plus
2 half lines.
●
The 405-line service was only monochrome, so there is no color information to
code in the output. That is why it requires far less bit rate than expected.
●
The values used for pixel resolution are non-square for visible and nominal equiv-
alents for the physical raster value. Sampling frequency and therefore resolution
in the horizontal axis may vary considerably from one application to another. The
noted values are commonly used, but you may use other values for different pixel
aspect ratios if there are parameter settings available for them in your compres-
sion system.
●
Film specifications: http://www.camerasunderwater.co.uk/web—site/info—/Technical.html
Interlace: http://broadcastengineering.com/ar/broadcasting_understanding_interlace/
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