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Rapid Eye Multi-Media DVR System Administrator Guide
Document 800-02953V4 Rev A 87
03/10
Comparing the Resolutions of Recorded Video
Figure 5-9 Identifying a Subject Using High or Moderate Resolution
Security and Presence
Before critical events occur, it is worthwhile to compare video recorded at Continuous
settings with video recorded using Event settings. You can then establish if the resolution
is high enough for your organization’s security needs. Consult your security personnel to
decide whether you need to establish the presence of known individuals. Lower resolutions
are usually adequate and take less storage. Samples of low-resolution and high-resolution
video images are shown in
Comparing the Resolutions of Recorded Video on page 87 .
Video images are bitmaps. When a camera window is dragged to a larger size, the pixels
are also enlarged. The image’s sharpness is not preserved. More stretching can degrade
the subject of an image beyond recognition. Compare
Figure 5-9 and Figure 5-10 . A high
resolution (704 × 480, NTSC) shows recognizable facial characteristics and very few
artifacts, such as pixelation, color variance and so on. If storage time is an issue, recordings
at a more modest resolution (320 × 240) shows almost as much detail. Applications to
establish presence or absence of personnel can use even lower resolutions. At 160 x 120
(NTSC) many facial characteristics of a known person are still recognizable even when the
imaged is stretched, as in
Figure 5-10 .
Detail of recorded video,
previewed at a resolution of 704
x 480, captured while optimally
sized. Shown here as it would
appear on a PC’s monitor.
Detail of recorded video,
previewed at a resolution of 320
x 240, captured while stretched
larger than optimal to compare
with higher resolution. Shown
here at stretched size.
Preview window