[simpits-tech] Re: Projector Screen

[Jim K.]

 >>>>>>From: Marv De Beque <mdebeque at woh.rr.com>
Subject: Re: [simpits-tech] Re: Projector Screen
To: Simulator Cockpit tech list <simpits-tech at simpits.org>
Message-ID: <BBB976D4.5E79%mdebeque at woh.rr.com>
Content-Type: text/plain; charset="US-ASCII"
Exactly what do these scalers do (CPU based and stand alone)?
Marv<<<<<<<<<<<<<<<<<


Marv,
Here is a real generalized overview of scalers.

A video scaler basically increases the number of horizontal line scans in a 
video image.   A basic U.S. NTSC television has 480 lines of video 
image.   Thats OK fine for a standard tv screen size but if you project 
that same image and increase its size to fit a home theater (HT) wall size 
screen you will see a line of video, then a blank line then a line of 
video, etc.   You will see those blank lines easier the closer you get to 
the screen.   Normally you can see them when you are 15 feet or closer to 
the screen.   At 15 feet the video will look fuzzy and the closer to the 
screen you get the more you will actually be able to see the individual 
scan lines.     Its like looking through blinds to see the video.  So 480 
lines is not very impressive to  watch on a large screen like a 115" 
diagonal HT screen where you are sitting 12 to 15 feet away from the screen.

Since HT video projectors are capable of projecting HiDef signals HT people 
use a video scaler to increase the number of horizontal video scan lines 
coming out of a satellite tv receiver, computer or a DVD player.   Although 
most HT people don't use sat tv as a video source since its video quality 
is really terrible and not worthy of projecting onto a big screen.  Its far 
to compressed to provide high quality video.  :-)))    But many HT users 
will use HiDef sat receivers or local HiDef antennas to project HiDef and 
that looks awesome on a HT screen.   Even a standard DVD video won't look 
very good when projected to a large HT screen.

Every scaler is capable of scaling to different resolutions (lines of scan) 
and with different overall video quality depending on the quality of the 
scaler.   I scale my DVD and sat tv signal to 720 lines of resolution then 
send it to my CRT projector and then onto my HT screen.   I also have a 
HiDef receiver but that doesn't need scaling since its already at a true 
1080 lines.

The scaler basically looks at 2 consecutive horizontal lines of video and 
the blank line in between them.  It then determines what would be in that 
blank line if it had video and puts in a video scan line.   As you increase 
the number of scan lines the picture quality will go up until you reach a 
threshold which is dependent on your equipment and original video 
signal.   This scaling system works pretty well and when you look at a 
scaled large screen you won't see any scan lines even if you get real close 
to the screen.

True HiDef video is 1080 lines of video.   It is far better than DVD video 
and is much, much better than any signal scaled to 1080 since each scan 
line is a true scan line and not an interpreted scan line like scalers 
provide.   So there is a great deal of projected video information and 
everything looks VERY crisp, clear and detailed.

If you are using a projector you almost have to use a scaler to get a good 
picture especially if are sitting close to the screen.   As I mentioned you 
can go the computer scaler route or go with a dedicated scaler.   There is 
a Viewsonic VB50 that that sells for about $80 that would probably work 
with games.   Many HT people use scalers that cost  $1500 and up.   There 
are some scalers in the $400 range but you get what you pay for and HT 
people are looking for extreme high quality since they spend a lot of time 
and money in their systems (video and audio) and theater room.

If you are thinking of going the projector route look at a CRT since it 
blows away digital projectors and plasmas.

Jim