What exactly is a scaler and how does it work?

Discussion in 'Archived Threads 2001-2004' started by Chauncey_G, Mar 6, 2002.

  1. Chauncey_G

    Chauncey_G Second Unit

    Joined:
    Jun 2, 2001
    Messages:
    291
    Likes Received:
    0
    I've been researching an upcoming FPTV purchase and have come across people talking about "scalers" as being an important component when using an FPTV. Can someone help clue me in?

    I also hear that using a HTPC in place of a scaler is a cheaper alternative. Can someone also let me know the role of a HTPC in this equation?

    Thanks in advance!
     
  2. Allan Jayne

    Allan Jayne Cinematographer

    Joined:
    Nov 1, 1998
    Messages:
    2,404
    Likes Received:
    0
    You do not need a scaler unless the projector requires an unusual scan rate (number of scan lines), or if the projector does not have an adequate choice of aspect ratios.
    One hypothetical example: The projector is 16:9, has a standard 480 scan line picture (525 scan lines total). There is no zoom mode, only "4:3" (shows a letterbox movie with black on all 4 sides) or "full" (shows the letterbox movie stretched out still with black bars on top and bottom. An external scaler of the right kind (up to you to shop around) can take the letterbox picture and spread it out over all 480 scan lines, throwing away the black scan lines on top and on the bottom so you now get a picture that nearly fills the screen. (For real 4:3 programs you flip a switch on the scaler so it does not spread out the picture).
    Another example: The projector is 4:3 and one of the scan rates is 1024 x 768 (768 scan lines of which 576 fit in the biggest 16:9 shaped space achievable). A scaler of the right kind will spread out a standard 480 scan line 4:3 program to occupy all 768 scan lines and spread out a wide screen program to occupy the inner 576 scan lines. If the projector has both the 640 x 480 and 1024 x 768 settings, DVD using the 1024 x 768 with (requires) a scaler will give a smoother picture than the 640 x 480 without (does not require) a scaler.
    You have to know your projector's capabilities as well as the kinds of input (HDTV, progressive scan DVD, etc.) you are going to use.
    Video hints:
    http://members.aol.com/ajaynejr/video.htm
     
  3. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0
    Analog video in NTSC format (american standard) is 480 interlaced lines.
    Front projection systems, since many are essentially computer displays, are capible of displaying higher resolution images than just 480 interlaced lines. Not only are they able to handle these higher res images- often they are expecting higher resolution images.
    In the early days of projection and big screen TVs, it became obvious that 480 interlaced lines, when blown up to big sizes, looked crappy. So a device called a line doubler is available to essentially take the 480 interlaced lines and deinterlace them, creating a "doubled" image- which results in less visible "scan lines" on screen.
    Again- as this concept developed- the scaler became the next step to take 480i pictures and make them "higher resolution".
    My projector, for example, expects a 1024x768 image. This is its native panel display- and anything it gets other than 1024x768, it uses and internal scaler to make 1024x768. However, that internal scaler sucks- so feeding it analog video looks kinda weak (scaling artifacts and weird jumpiness is the result because the internal scaler does a poor job of making 480 into 768).
    So people like myself employ external scalers (or in my specific case a HTPC) to take the 480 NTSC signal and "scale" it to create other resoltions. It takes the 720x480 image and makesit 1024x768, or whatever you have your scaler set to output.
    It takes the available info and does some math to fill in the info "between the lines"- usually resulting in a more smooth and film-like image.
    If you're interested in some more technicals of scaling, check this out:
    http://www.avsforum.com/avs-vb/showt...hreadid=103815
    -Vince
     
  4. Bill Lucas

    Bill Lucas Supporting Actor

    Joined:
    Mar 20, 1999
    Messages:
    530
    Likes Received:
    0
    Vince is right on target. An external scaler should ALWAYS be used with a digital projector, CRT projector or plasma display. There's also a great benefit for someone with an HDTV RPTV that wants the best image possible out of their display unit. Matching the native resolution pixel for pixel gives a tremendous improvement in image quality and keeps artifacts to a bare minimum. Regards.
     
  5. Chauncey_G

    Chauncey_G Second Unit

    Joined:
    Jun 2, 2001
    Messages:
    291
    Likes Received:
    0
    Thanks for the replies! I'm starting to get it. Now for the HTPC thing. In the thread that Vince linked me to I see some posts saying that a PC does the job just as well as a scaler, but for less $.
    OK, I must've grown some extra brain cells because I just noticed this current thread on HTPC's in which Vince provides some GREAT links! They answered most of my questions, so thanks to the "edit" function those questions just went bye-bye!
    Still have a couple, though: are there any pre-fabricated HTPC's or should you just build your own (I've never built a computer, though I have a few friends who do that I could enlist for this); and does anyone have recommendations for good scalers(not too pricey, please)?
    Thanks again for any and all help!
     
  6. Bob McElfresh

    Bob McElfresh Producer

    Joined:
    May 22, 1999
    Messages:
    5,182
    Likes Received:
    0
    One of the magazines, Sound & Vision I think, has a regular column on using a HTPC. He does reviews of both hardware and software. Might be worth checking out some back issues.
     
  7. Jack Briggs

    Jack Briggs Executive Producer

    Joined:
    Jun 3, 1999
    Messages:
    16,738
    Likes Received:
    129
    Actually, that's Stereophile Guide to Home Theater that runs the HTPC column.
     
  8. Vince Maskeeper

    Vince Maskeeper Producer

    Joined:
    Jan 18, 1999
    Messages:
    6,499
    Likes Received:
    0
     
  9. Chauncey_G

    Chauncey_G Second Unit

    Joined:
    Jun 2, 2001
    Messages:
    291
    Likes Received:
    0
    This is great. Thanks for all the fantastic info. I want to be able to thoroughly research this FPTV (and related items) purchase as much as I can before I buy. I don't mind shelling out the cash if I know I'm going to get good stuff, and you all have helped out tremendously.
    Thanks again, and if there are any more recommendations, bring 'em on! [​IMG]
     

Share This Page