Lumagen VisionPro - Manual (Page 28)

Vision Pro
™ User Manual and Installer Guide
© 2003 Lumagen, Inc. 25 Rev 1.13
Selecting the Output Resolution
The Society for Motion Picture and Television Engineers (SMPTE) standards for 480p,
720p, 1080i and 1080p are used as reference points for output timing. Other resolutions
and vertical-refresh-rates are derived from these standards.
It is important that the optimal output resolution is selected. For fixed-pixel devices, such
as DLPs, and LCDs, the output resolution should be set to the native vertical resolution.
For CRT projectors, the best choice is more involved, since it depends on tube size,
focus, phosphor spot size, and video-bandwidth. Some suggested starting points, based
on tube size, are 720p for 7 inch, 840p for 8 inch, and 960p for 9 inch. Consult a home-
theater specialist for help selecting the optimal resolution.
High-definition direct-view and rear-projection televisions typically support 480p and
1080i. Some also support 540p or 720p. If 720p is supported, it is the recommended
resolution, because 1080i suffers from display interlace-artifacts that reduce the
perceived vertical resolution to roughly the same as 720p provides. Since the output is
over-sampled horizontally, 720p provides nearly equivalent perceived vertical and
horizontal resolution as 1080i, and it eliminates interlaced-display artifacts. If 720p is not
available, 1080i is most likely best for these displays since, even though it has interlace-
artifacts, it eliminates the visible line structure often apparent at 480p and 540p.
A vertical-refresh-rate of 59.94-Hertz works well for NTSC, and PAL M, material. For
PAL (except PAL M) and SECAM, 50-Hertz may provide the best picture. Note that the
selected rate must be supported by the display at the selected vertical resolution.
Note:
The maximum resolution depends on the vertical rate and on the output aspect ratio.
For an output aspect ratio of 1.33, the maximum resolution is 1080p at all vertical rates.
At a 1.78 output aspect ratio, the maximum resolution is 1080p at 60 Hertz, 900p at 72
Hertz, and 840p at 75 Hertz. For an output aspect ratio of 2.35, the maximum resolution
is 768p at 60 Hertz, 640p at 72 Hertz, and 600p at 75 Hertz. The software attempts to
prevent illegal combinations of resolution, vertical rate and aspect ratio, but given that
there are millions of combinations, not all cases could be checked. If noise is observed on
the screen, reduce the resolution, aspect ratio, or vertical rate.
The minimum output resolution is 480p. For NTSC, and PAL M, this is also the
minimum suggested resolution for output aspect ratios of
≥
1.78. For other formats the
minimum suggested resolution is 576p for output aspect ratios of
≥
1.78. For output
aspect ratios of less than 1.78, the suggested minimum output resolution as the aspect
ratio approaches 1.33 is proportionally increased to 640p for NTSC, and PAL M, and
768p for other formats. Lower resolutions work with these smaller aspect ratios, but
material that is “enhanced for 16:9 televisions” will be set to the minimum scale factor of
1.0 and cropped to fit the screen. Note, for these calculations, 1080i is the same as 540p.