External Scalers

Discussion in 'Displays' started by Michael FF, Sep 8, 2003.

  1. Michael FF

    Michael FF Stunt Coordinator

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    Do you use an external scaler with your front projection DLP projector? If your projector has an internal scaler built in, does the external do a better job at creating a sharp image?
     
  2. DaViD Boulet

    DaViD Boulet Lead Actor

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    It depends.

    In the old days of predominantly CRT projectors, external scalers were the only type of scaling around...so they were mandatory if you wanted anything other than a scan-line filled 480I image on your big-screen.

    Just to be clear,

    in the strictest sense, converting an interlaced image to progressive is called "deinterlacing" (480I - 480P). Converting an image of one resolution to another is called "scaling" (480P to 720P). The now moot term of "line doubling" was sortof globally applied to both concepts depending on the product and manufacture or salesperson...so I don't like to use it because it's not a technical term and like "anamoporphic DVD" it only leads to confusion.

    Faroudja had come up with the 3-2 pulldown concept for film-source material and had "sortof" patended the idea so no other scaler/deinterlacer company offered it. Farouda charged $$ for their scalers/deinterlacers and without a doubt theirs produced the best image.

    Then Dwin came out with a deinterlacer/scaler with 3-2 pulldown for film and Faroudja took them to court. The court ruled that no one could "patend" the concept of reversing 3-2 pulldown per-se (though the court case almost put Dwin out of business at the time from what I was told).

    So Dwin got to keep 3-2 pulldown and then Faroudja got smart-they decided to sell affordable chips with their 3-2 pulldown and patend algorithms for processing native 480I material and lots of products started using them...from progressive-scan dvd players to digital projectors.

    Now, deinterlacing used to be a hard job but chips like Faroudja's made it easy (and cheap). Scaling to various resolutions has also improved over the years and is now quite easy to do well affordably.

    What's all this mean? It means that most front-projection digital devices have really *great* picture quality with good 480I sources because they do such a good job deinterlacing and scaling.

    You can indeed improve the image by going with $$$ outboard gear if you want. But where the most improvement is coming from these days is going with an all-digital video connection that keeps the signal clean. A PC feeding a DVI video signal to your projector will probably look better than using the analog component out of your DVD player feeding a Faroudja external scaler.

    And some scaling companies have gotten smart and included DVI in/out connections on their scalers so you can keep the video signal digital the whole time. That's a win-win!!

    Bottom line: You can get fanastic PQ just running componnet (interlaced or progressive) to most decent HT-oriented projectors and HDTVs these days. However, sometimes you will see an improvement by using a high-end external scaler. But where most folks see the biggest gain seems to be going DVI...whether they use a cheap $199 bravo DVD player, HTPC, or external scaler with DVI in/out.

    be sure to check out the avscience forum for more info if you want to educate yourself more in-depth.

    -dave [​IMG]
     
  3. alan halvorson

    alan halvorson Cinematographer

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    So - I am out of touch - are there any reasonable priced scalers available for use with CRT projectors?
     
  4. DaViD Boulet

    DaViD Boulet Lead Actor

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    It depends on your definition of affordable.

    You can spend anywhere from less than $1K on a 480i-480P processor (works well with lower-res CRTs that don't show scan-lines at 480P) to some that cost a couple grand to some that cost $5K and up.

    What many folks are doing these days with DVD software is configuring a PC to be optimized for DVD playback. They get a good video card and software geared towards picture quality and their PC scales the DVD to a good resolution match for their CRT (folks also doing this using digital projectors).

    Most CRT projectors have a "sweet spot" where, scanning at a certain resolution, their scanlines exactly touch...so there's no gap *and* no overlap. Go lower-res and you see gaps between the scan-lines. Go higher-res and you get a softer/blurrier picture bcs the scan-line overlap each other.

    This best resolution may not necessarily be one of the normal resolutions we think of (480, 720, 1080). It might be some odd-ball resolution like 860.

    Using a PC can give CRT guys the flexibility to "dial in" the resolution setting that best fits their CRT projector.

    And you can do all this for less than the price of a mid-level scaler...*and* your picture quality can end up being just as good!!

    -dave
     
  5. Craig Robertson

    Craig Robertson Supporting Actor

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