7
circuitry, while vertical resolution is a function of the
scanning frequency (the number of scan lines in each
picture). Given these mechanisms and with an average
size picture tube of 8-10”, they designed the 525 line
broadcast standard so that viewers would not see the
scan lines when watching TV. They had no idea that
someday people would be projecting home theater
video images with diagonal screen sizes of 10’ and
more.
Based on those NTSC parameters, using a 10 ft. diago-
nal screen would require the viewer to be located more
than 45 ft. from the screen to see the picture as it was
intended without scan lines! Unfortunately, today’s large
screen installations have scan lines that are quite visi-
ble, especially with some of the latest high resolution
monitors and projection televisions. The VP251 elimi-
nates this problem by scan doubling the 525 interlaced
lines (only 480 lines are actually visible) to become 480
progressively scanned lines. The result is the elimination
of visible scan lines and increased brightness and detail.
The image produced by the VP251 is virtually film-like in
detail, motion and color.
STAGE C DETAIL PROCESSING: Luminance
Bandwidth Expansion
There is a major limitation with most contemporary pro-
gram sources — lack of frequency response. The best
video sources such as satellite dish reception and
laserdiscs can provide acceptable resolution (400 plus
lines of horizontal resolution). Other more common
sources however, such as VHS tapes (230 lines), are
clearly deficient. The problem is compounded when the
scan lines are doubled along with other signal process-
ing. The lack of high frequency detail becomes very
obvious when the more common sources are used.
The resultant picture is free of scan lines but dull, with a
serious loss of definition. The solution is to expand the
high frequencies without producing annoying and picture
degrading artifacts.
The bandwidth expansion circuitry in the VP251 is
exceptionally sophisticated, using Faroudja’s double dif-
ferentiation techniques to sharpen the edges of both
horizontal and vertical details. The result is a sharply
detailed image that appears crisp and three dimensional
with no visible negative side-effects. This process can
effectively double the perceived bandwidth and there-
fore the resolution of the incoming signal.
FAROUDJA VP251 APPLICATIONS
– While the tech-
nical accomplishments of the VP251 represent years of
intense research and development, its use is straightfor-
ward and direct. The block diagram (above) illustrates a
typical home theater system configuration and shows
how the VP251 would be inserted in the signal path.
Many entertainment sources benefit greatly by the
VP251’s unique attributes; laserdisc, VHS video, S-
VHS, DVD, cable TV, broadcast TV, etc. The VP251 has
proven to be an invaluable tool in other presentation dis-
ciplines where image quality is important; computer data
displays, professional installations in boardrooms and
media rooms, military installations, government agen-
cies and academic uses in schools and colleges. From
the quality of its individual parts to its state-of-the-art
patented circuitry, the VP251 is truly in a class by itself.
There is simply no finer video processor available.
VIDEO
TUNER
LASERDISC
PLAYER
VCR
V
ID
E
O
S
W
IT
C
H
E
R
VIDEO PROCESSOR
Y C
R G B
SYNC
R-Y
B-Y
Y
CRT
PROJECTOR
WITH 7'' LENSES
OR
DLP
PROJECTOR,
PLASMA,
COMPUTER
MONITOR
Monitor
COMPUTER
DISPLAY
COMPOSITE
VIDEO
R
G
B
SYNC
/
TYPICAL VP251 SYSTEM UTILIZATION
VP251
