I am researching to purchase a projector. A technicality which I have researched on this forum with no luck is my problem below.

A sad fact is the jump in price from say a 854x480 to 1024x576 projector. The picture quality of a 854x480 such as the IF 4805 is superb, however.

The resolution of a 854x480 projector "matches" the resolution of NTSC, where PAL matches a 1024x576 pj.

Does this matter, or does a scaler do such a good job that the difference is not noticeble?.

To put the question in another way. Considering the fact that I will be watching mostly PAL DVD's, should I go for a 1024x576 projector or does the scalers do a close to perfect job?. (ignoring the fact of the 1024x576 has a higher res)

[LV426]

Regardless of the standard of the scaler, if you display a 576 line PAL signal on a anything x 480 display, you by necessity have to degrade it - reduce the amount of vertical detail.

In addition, the coarser the display structure, the greater the probability that you will see the screendoor (grid) structure of the pixels on the projected image.

More is better.

I'm afraid I can't answer the question with certainty, but can pose another similar one, I'm wavering between a 1024x576 dlp and 1280x760 lcd, there is a train of thought that says "more pixels = better" even non-native, but would the increase in resolution here off-set the advantage of the native resolution.

Also using a DVD player or HTPC, is the image is overscanned are you accuratly displaying 1 pixel on the source dvd to one pixel on the screen? How do you ensure you do this?

[LV426]

The reason "more is better" (even if this results in upscaling, compared to none for another device) is

Pixels are square. Even small ones.

Interpolation (upscaling) doesn't add detail - it can't. What it does do is re-shape the incoming array of square pixels of colour into a dithered structure that fits the smaller sqaures of the display. This, in effect, changes the image from a matrix of squares of one size, to a larger matrix of smaller squares, with the shape and position of the originals dithered onto it. The end result is what is in fact an equally detailed, but actually softer image (i.e. the original square pixels aren't as clearly defined).

Which leads me on to human perception. The human brain is actually quite adept at doing it's own interpolation of detail but it is only accustomed to doing so when the incoming signal (from the eye) is soft - poorly focussed vision is something that arises in nature. If it's sharp, then it turns its detail enhancement off.

Sharply defined pixels are thus seen as sharply defined pixels - and the brain makes no attempt to further interpret what it sees. In a way the pixel structure actually confuses the brain into believing that what it's seeing is what it's meant to be seeing. Whereas softly defined pixels are interpreted as out of focus by the brain, and in it better able to interpret what it sees. So you get the subjective impression of more detail.

[Bristol Pete]

I concur with Nigel on this.

However, a while back I demoed a Sharp Z91E which was a native 4:3 PJ, but I could switch it too 16:9 - 854 x 480. This was a lower resolution than my own PJ but the picture on the lower res 4:3 DLP machine blew it away. Far more film like, solid and a far more overall 3d image.

To be honest, since then I have always let my eyes do the talking when it comes to looking at projectors, irrespective of the paper spec though as Nigel says there is a science here.

Just my opinion.

Cap

[LV426]

...and here is some evidence

The picture on the RIGHT is the original. The picture on the left is UPSCALED from the one on the right (in this case by 4x in each direction).

Judge for yourself which is the more natural-looking - appears to have more detail, but blurred. Which one shows the writing on the flag more clearly and especially, note the individual stars on the stars & stripes. And then remind yourself that the left picture was created from the right.

[JonMace]

the first pic looks better is that the upscaced one? left and right has to have a perspective.

[LV426]

Excuse me? Not sure I follow what's unclear about

The one on the right is the original; the one on the left is upscaled from it.

However, if you read (or look at the page) from left to right, then the upscaled one will come first. ??


Or....

<<< left right>>>

Thanks Nigel,
Great example, it is so good that it is difficult to believe, especialy the stars. It would have been nice to be able to see more such scaling examples.

Is it correct to assume then that a NTSC DVD will perform better on a ??? x 480 display than a PAL DVD (less scaling)?.

What factor was this upscaled by? I wonder if upscaling by 50% would have such a dramatic effect.

[LV426]

Originally Posted by spamboy

What factor was this upscaled by? I wonder if upscaling by 50% would have such a dramatic effect.

Originally Posted by nigel

(in this case by 4x in each direction).

Done deliberately to over-emphasise the principle. Upscaling by a smaller amount will clearly have a less profound effect.

Originally Posted by kobus

Is it correct to assume then that a NTSC DVD will perform better on a ??? x 480 display than a PAL DVD (less scaling)?

The purpose of the demo is to illustrate that up-scaling (when done well) can actually improve the source - at least subjectively. In order to get a PAL (...x576) image displayed on a ...x480 display, it has to be downscaled - in other words, actually degraded. This is never a good thing. So, yes. But better still to display both on a higher resolution display (assuming a competent scaler).

[MikeK]

Not really, it totally depends on the DVD - but all things being equal, you could assume that I suppose.
Theoretically (and if you use DVI from a suitable player, then possibly actually), there is no vertical scaling involved when putting an NTSC anamorphic DVD onto a 854x480 panel. However, horizontal scaling will still have to happen - the DVD itself only contains 720 pixels horizontally in each "frame", so a 720:854 horizontal upscale is required - however, as the content is already squeezed in anticipation of this upscale being done, the scaler can simply go ahead and do it without worrying about the aspect ratio. This makes it very easy. For PAL on an 854x480 panel, it's a little more complicated - on a 1024x576 panel, it's exactly the same as above. It's no coincidence why these panel sizes have been chosen!!!

In fact, up/downscaling is practically always required in some form or another. Remember DVD was not designed to directly drive digital panels - it was designed to be compatible with the various analogue TV systems in use at the time - the "frame" sizes of 720x480 (NTSC) and 720x576 (PAL) were not arrived at by accident (note that neither of them is 4:3 or 16:9).

As to the scaling itself - there are scalers and there are scalers - don't assume that they are all as good as each other, because they aren't - not by a long chalk.
There are many different methods of doing it, and as usual, the most effective also tend to be the most expensive.


As to the examples above, that's one case where upscaling has improved things - you could just as easily post examples where it doesn't. Don't forget that upscaling motion video is a little more complex than just upscaling a jpeg photo - for a start, video upscaling has to be done on the fly and in real time - so the more complex the upscaling algorithms, the more computing horespower is required, and the cost starts to rise steeply. If there isn't enough "grunt" to do it properly, then all kinds of artefacts can start to appear, even though you may end up with a picture that contains more pixels.