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Discussion Starter · #1 ·
I am a long time CRT owner, but thingking about 3 chip DLP. Here is the question: if you feed it a progressive line-doubled signal from a video processor, it's internal engine would have to scale it to a native panel resolution, say 1024x768. So what's the benefit of having an external scaler which would provide that native resolution vs line doubler? Scaling artifacts depend mostly on quality of deinterlacing engine. What am I missing?
 

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It depends on the projector you buy. If it has a very high quality scaler built in you are good to go. Most units do benefit from an outboard scaler but some like the InFocus LP340/350 (single chip DLP) work great on their own. The internal scalers are improving and this should be a consideration when researching and making your purchase decision.
 

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Being a Crt owner it has taken me a while to get my head around this fixed panel thing. To put it the best way I know how.

A Crt needs a scaler that can scale the incomming video and output it at its sweet spot (ideal rate depending on spot size/focus etc).


With a fixed panel display you know exactly what the sweet spot is (its native panel resolution - vga/svga/xga/sxga etc). Of course most in built scalers fall down in several areas, such as deinterlacing etc, so an outboard scaler of quality is a good addition.


Now unless you only have a Vga device or perhaps the inbuilt scaler is good at scaling but no at deinterlacing, choosing a line doubler means it is only going to be used as a deinterlacer and the inbuilt scaler is still going to have to scale to the native panel resolution. Now this may yield good results, but if the inbuilt scaler does a poor job of scaling then a doubler is next to useless in my view.


If a device has a bad inbuilt scaler then no doubt that big improvements can be made by getting an outboard scaler.

Although it is best to get a scaler that will scale to the "actual native rate of the device", and one that does a good job of doing both deinterlacing and scaling.

Not many devices have good scalers built in and many outboard ones are also not perfect.

Try many before you buy its well worth the effort.


DavidW
 

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True deinterlacing is a very different process from scaling, and has different artifacts, such as horizontal combing and/or blurry motion. Poor scaling can cause fuzzy images and stairstepping on edges. Some simple image processors perform "deinterlacing" by scaling each field up to frame size, and displaying them sequentially. This is called spatial deinterlacing, and it's not really deinerlacing, since the fields are never shown together. In this case, the "deinterlacing" artifacts are similar to scaling artifacts.


Projectors have traditionally had terrible deinterlacers built in, while the scaling hardware varied in quality. The availability of relatively cheap (but decent) image processing chips is improving the situation.


Dave
 

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Discussion Starter · #5 ·
Makes sense. What I was referring to is that if you've got something like faroudja doubled signal w/ DCDi processing (or the new chinese DVD player), and you use it with a high end 3-chip DLP, you may not need to get a more expensive scaler to go to a true resolution.
 

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BXA,


Deinterlacing is still an art that some companies do better than others.


But most of today's projectors do a remarkable job of scaling a 480p image up to the native panel resolution.


If the projector you are buying was designed in the last 12 months it probably has a great internal scaler. if the projector's design is more than 2 years old, it probably has a poor internal scaler. Imbetween 1 and 2 years would be toss up.


If you tell us the 3 chipper you are considering, someone might have specific experience with it.


I guess the bottom line is if you want something that will give you as good of image as possible, then a deinterlacer with scaling to your native resolution is the best way for you to go. But most of today's best projectors only need deinterlacing work to be done externally, the scaling is done perfectly inside the machine.


-Mr. Wigggles


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The Mothership is now boarding.
 

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I've been thinking the same thing as BXA. What I'm actually looking at is the LT150. Anyone have an idea how that would work with 480p?


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/frode
 
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