Why does everyone always want to fill the whole screen?

NicolasB

Distinguished Member
Something I've never entirely understood about AV enthusiasts is the way they can't bear to leave part of the screen unused. In particular, if they have a high resolution display, they insist on upscaling images to fill the whole screen.

Question is: why?

You can't possibly get any more detail into the image by doing this, no matter how good the scaler is. Sure, it's bigger, but it's also blurrier.

Why, I find myself wondering, doesn't anyone seem to want to watch lower-definition images letterboxed, at native resolution, with genuine, right-from-the-source, 1:1 pixel mapping?

If you've got, say, a 1920x1080 display, I'd have thought the best option would be to watch 720p actually as 1280x720. Standard definition does require to be scaled a little, otherwise the aspect ratio will be wrong, but even so you could scale 4:3 PAL to 768x576, and anamorphic PAL to 1024x576 and at least get 1:1 mapping vertically.

This curious compulsion to fill the whole display always reminds me of people who refuse to watch 2.35:1 film transfers because they don't like the black bars at the top and bottom of the screen while it's playing. :)
 

NonPayingMember

Previously Liam @ Prog AV
Surely an AV enthusiast would have a decent scaler and hence doesn't worry about such things :rotfl: :rotfl: :rotfl: :rotfl:

Seriously though, if you've put a projection system in for perfect balance of throw distance, image size, and viewing distance, having half the material shown at only half the width would be ridiculous!! 50% of the time the image would be too small/big for the "sweetspot" viewing position.

Out of interest - do you watch material at only it's native resolution???
 

gIzzE

Distinguished Member
Hmm I wonder why???:confused: :D

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NicolasB

Distinguished Member
Liam @ Prog AV said:
Surely an AV enthusiast would have a decent scaler and hence doesn't worry about such things :rotfl: :rotfl: :rotfl: :rotfl:
Well, that was my point: a scaler cannot add detail to the picture. The best it can possibly do is make it large and blurry rather than large and pixellated - but is large and blurry actually preferable to small and sharp? I've never understood that.

Seriously though, if you've put a projection system in for perfect balance of throw distance, image size, and viewing distance, having half the material shown at only half the width would be ridiculous!! 50% of the time the image would be too small/big for the "sweetspot" viewing position.

Out of interest - do you watch material at only it's native resolution???
Well, as a rule I don't have much option, as I don't have a large hi-def display :) but certainly if I'm watching video clips on my PC I always watch them at native res, I never scale them up to full-screen. Similarly, if I need to run Windows at less than full-screen resolution for some reason I always letterbox it rather than have my graphics card upscale it. (This isn't altogether analogous, I know).

My experiences with demos of hi-def displays and projectors (including a fairly high-end CRT projector one time) hasn't changed my mind: I simply don't like watching SD on a very large screen, no matter how good the scaling is.

The way I see it, it isn't actually meaningful to talk about there being an ideal image size in a setup: to me, the size of the pixels matters more than the size of the picture. If you take an SD picture and upscale it, then now matter how good the scaling is, the lack of sharpness always annoys the hell out of me. Thus, the ideal image size is different for different signal resolutions on the same display hardware. The benefit of hi-def (to me) is the fact that it allows you to make the picture bigger and get the same level of detail; by contrast, most other people seem to set it as giving you more detail for the same size of picture.

gizlaroc said:
Hmm I wonder why???:confused: :D
I'm not suggesting you mess up the aspect ratio :rolleyes: the question is, if you have a 1920x1080 display, why would you scale anamorphic PAL up to 1920x1080 rather than letterboxed 1024x576? Or why would you upscale 1280x720 rather than viewing it native?
 

gIzzE

Distinguished Member
NicolasB said:
I'm not suggesting you mess up the aspect ratio :rolleyes: the question is, if you have a 1920x1080 display, why would you scale anamorphic PAL up to 1920x1080 rather than letterboxed 1024x576? Or why would you upscale 1280x720 rather than viewing it native?


Those 2 photos above are with the Crystalio Scaling the image to fill the screen and then with it passing through the 720x576 pal source with no scaling at all, so unless you scale when feeding it a widescreen image the signal it is messing with the aspect ratio and the vieiwing area is reduced by 48%. I can see what you are saying but it exactly the reason we all buy scalers. :suicide:
 

NonPayingMember

Previously Liam @ Prog AV
NicolasB said:
Well, that was my point: a scaler cannot add detail to the picture. The best it can possibly do is make it large and blurry rather than large and pixellated - but is large and blurry actually preferable to small and sharp? I've never understood that.
I think you maybe need to see a (decent) scaler and a HD screen in action . Giz is highlighting that his Crystalio hardly blurs the image out of distinction, my Lumagen Pro on a 50" plasma looks razor sharp to my eye also... and I'm quite a critical viewer. I'm happy to show you if you fancy a trip out to see what can be done with SD, I'm sure if your nearer another forum member they would be happy to show you theirs too. You may be missing on something you would actually enjoy by assuming a picture can only be worse with upscaling based on your perhaps limited experience. Only trying to help anyway, if you're happy with what you got enjoy. But I guess that will mean you are limited to say a 36" CRT or having weirdo image size:viewing distance issues with a fixed pixel device.
 

NicolasB

Distinguished Member
cwick said:
Umm ... so you can actually see it when sitting on the sofa ? At which distance scaling artifacts aren't very noticable anyway, and are preferable to squinting at a little postage stamp size square in the middle of your nice big telly. That's why I'd do it anyway.
If that's your problem then either the screen is far too small or you're sitting far too far away from it.

Liam @ Prog AV said:
I think you maybe need to see a (decent) scaler and a HD screen in action.
I have, thanks, several times.

Giz is highlighting that his Crystalio hardly blurs the image out of distinction, my Lumagen Pro on a 50" plasma looks razor sharp to my eye also...
Well, no offence, Liam, but that's physically impossible, unless you're sitting so far from the screen that the maximum resolvable level of detail is only that of the original source material anyway. You can't create detail that isn't there. All you can do is blur the edges of the pixels.

I've attached a simple illustrative screenshot. You have five bits of text here. The first represents a native 1080p image. The second represents that image downscaled to anamorphic PAL, then upscaled to 1024x576. The third is the image downscaled to anamorphic PAL, then upscaled back to 1920x1080.

Image 4 is text designed to look good at 720x576, i.e. a 4:3 PAL signal. Image 5 is the same image upscaled to 1440x1080 (i.e. a 1080p screen but preserving the aspect ratio).

Out of curiosity, does anyone know what scaling algorithms scalers tend to use? I rather suspect they'll use something pretty basic: maybe bicubic if you're lucky, perhaps even just bilinear. For the scaling in my sample I've used the Lanczos3 algorithm - and I would be astonished if any real-life scaler used an algorithm as sophisticated as that, so almost certainly the effect a real life scaling device would have on the image quality would be worse than in this screenshot.

So: put your face about a foot from your monitor screen, close enough that you can almost make out individual pixels in the native hi-def text but not quite, and then ask yourself if you prefer image 2 or image 3. Then ask yourself if you prefer image 4 or image 5.

Seems to me you'd want to watch SD at image 2 size, and HD at image 1 size.

(You need to view the picture full size, not just the "attached thumbnail"! :) )

And no, I have not formed this opinion on the basis of this screenshot, in case anyone is dumb enough to imagine that I might have. It's simply an illustration of what I'm talking about.

Only trying to help anyway, if you're happy with what you got enjoy. But I guess that will mean you are limited to say a 36" CRT or having weirdo image size:viewing distance issues with a fixed pixel device.
I've been holding off on a hi-def purchase until I can get something that is genuinely 1080p native (input and screen) and a decent quality and size. I was very tempted by the Ruby, but I'm a little short of funds, and I really can't face going into total blackout just to watch TV. (Worried about bulb costs, too). If the SXRD rear-projection sets in the Autumn live up to the hype, I'll be buying one of those, probably the 70" model for a viewing distance of 9 or 10 feet. At that distance I suspect SD will look a lot nicer letterboxed at 1024x576 than at 1920x1080: we'll see.
 

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NonPayingMember

Previously Liam @ Prog AV
Fair enough Nic. Only trying to help. For clarification I've never once said I'm creating detail, just that for my viewing distance and screen size it looks razor sharp. There's always gonna be a penalty to pay with a larger screen, I'm never saying it will be as perfect as the original source, but all factors considered it's hardly unwatchable as you are making out!! My opinion anyway.

N.B. 1024 x 576 will still be a horizontally scaled signal - you just can't win with video standards these days LOL!!!
 

gIzzE

Distinguished Member
Nic I totally get what you are saying and it makes perfect sense, but to not scale Pal on a 1920x1080 display the image is going to be tiny, and that is what I tried to illustrate with the two pics above.
But take a 9" CRT projector and 1080i material, why does the image look better when being deinterlaced to 1080p through a Crystalio scaler? Everything says that 1920x1080i should be fine and look razor sharp, and by deinterlacing it with simple scaling techniques should really soften the image if anything, but it doesn't, it looks sharper! That is because a processor does so much more than just scaling.
On the BenQ HD2+ DLP projector scaled and processed 480i looked as good as 480p fed in on pass thru mode, when you were sitting so the screen sizes looked equal, you had to be about 12ft back with the scaled, screen filled image or around 5ft back with the small pass through image. I personally would prefer to keep my furniture in the same place and let the processor do its job, I can imagine what my wife would say if we had to move the room around everytime we changed channel and it went from SD to HD etc. :rolleyes: ;)


I have long said that every display should have a pass through mode, not only for the reasons you say but also so it makes life easy to see when you are scaled correctly when feeding it native res.
 

NicolasB

Distinguished Member
gizlaroc said:
but to not scale Pal on a 1920x1080 display the image is going to be tiny, and that is what I tried to illustrate with the two pics above.
Well, that depends on the size of the screen. If you're dealing with a 37" LCD panel then yes, you are going to have to scale up the picture or it'll just look silly. :)

But suppose you're dealing with the aforementioned 70" SXRD rear-projection set. Using my "as near native as possible" approach you would be watching 1080i or 1080p material on a 70" screen; you'd be watching 720p material on a 47" screen; anamorphic PAL would be the equivalent of a 37" screen; and 4:3 PAL would be on a 30.5" diagonal 4:3 screen (768x576). All of these would have the same viewing distance - somewhere round 9 or 10 feet.

The equivalent CRT TV screen sizes would actually be a couple of inches larger than the SD values suggest, because a so-called because I'm measuring the image diagonal, and a CRT of (say) 36" size doesn't actually have a 36" picture, it's more like 34". So our not-so-scaled PAL signal gives us a picture size equivalent to nearly a 40" widescreen CRT TV, or a 32" 4:3 TV - that's plenty big enough for SD viewing at a distance of 9 feet! If anything, actually a little bit big on the big side.

gizlaroc said:
But take a 9" CRT projector and 1080i material, why does the image look better when being deinterlaced to 1080p through a Crystalio scaler?
Okay, please don't misunderstand me: I'm not suggesting that "scalers are useless". Scalers do a great deal more than scaling: switching, signal format conversion, deinterlacing, multi-point gamma correction, all sorts of goodies; and, as Liam points out, when viewing an SD signal you actually have to do some scaling in at least one direction, or you mess up the aspect ratio.

Indeed, to be able to watch SD at native resolution on a hi-def screen you will probably have to use a scaler(!) because the screen probably won't have a native resolution option.

But you could, for example, programme a scaler to convert an anamorphic PAL signal into a 1920x1080 signal which consists of the actual picture scaled to 1024x576 and the rest of the screen filled in black, rather than scaling the picture up to 1920x1080. The scaler would still be doing all of the other stuff that it normally does - deinterlacing, white balance, gamma correction, etc. - it's just that the non-black part of the picture would be smaller.

gizlaroc said:
I personally would prefer to keep my furniture in the same place and let the processor do its job, I can imagine what my wife would say if we had to move the room around everytime we changed channel and it went from SD to HD etc.
No, but the point of what I'm suggesting is that you don't move around the room, you stay where you are and let the picture size change so that it is always the optimal size for the underlying signal resolution.

I actually find upscaled SD objectionable enough that I feel obliged to sit farther back from the same size screen if it's showing upscaled SD than I do if it's showing native HD - again, it's the size of the pixels that determines my comfortable viewing distance, not the size of the picture.
 

Welwynnick

Distinguished Member
NicolasB said:
it's the size of the pixels that determines my comfortable viewing distance, not the size of the picture.
Now that is a good point.

My rule of thumb is to not to consider the screen size but sit 3438 pixels away!

Mind you, with a good CRT display, I do think you can comfortably sit coser.

Nick
 

Nic Rhodes

Distinguished Member
I have allot of sympathy for this way of thinking and thinks it holds an interesting point of view. I am another one who like to watch from a 'distance'.
 

gIzzE

Distinguished Member
Sorry Nic, I think we are just going to have to agree to disagree on this one.

I would be interested to see the SXRD in pass through mode with SD material (does it actually have a pass through mode?) Vs a scaler filling the whole screen.


edit: NicolasB that was aimed at, not you Nic.
 

redpavlos

Active Member
I'm another one who likes to watch from a distance, but I don't necessarily want to fill the screen.

By that I mean that if the movie is shot for 2.35:1 or 4:3, then that's the way I like to see it. In these circumstances I don't mind black bars at the top/bottom, or at the sides.

I do prefer scaling up an SD image to fill the height of my 50" screen, simply because of where I sit in relation to the screen.

The internal scaler on my screen is particularly good at dealing with text, by the way. I don't know how it does it, but it's effective. More difficult to do well is de-interlacing, irrespective of size.

If I want the best picture quality, comparing like-for-like viewing distances in terms of picture height, then my 20" crt broadcast monitor is the one to use.

But I rarely watch that way.

The point is, viewing on a large screen and listening on high quality home cinema speakers offers a completely new and engaging experience with a huge step-up in 'wow' factor.
 

Dale Adams

Active Member
NicolasB said:
Out of curiosity, does anyone know what scaling algorithms scalers tend to use? I rather suspect they'll use something pretty basic: maybe bicubic if you're lucky, perhaps even just bilinear. For the scaling in my sample I've used the Lanczos3 algorithm - and I would be astonished if any real-life scaler used an algorithm as sophisticated as that, so almost certainly the effect a real life scaling device would have on the image quality would be worse than in this screenshot.
Be astonished, then. Lanczos3 is a just variety of a windowed sinc function. All the algorithms used in DVDO scalers are based on windowed sinc functions for the filter coefficients. I'd be very surprised if the better scalers don't do this as well. The days of linear interpolation (i.e., "bilinear") have been over for a while now, although that does have it's place in certain circumstances.

You'll probably find that the scaling algorithms used by many of the video processors (chips and boxes) are considered proprietary and hence are not disclosed. That's likely going to be the case for any company which has developed it's own scaling algorithms.

By the way, the highly-aliased text example you use is not representative of normal video material. From personal experience I've found that many multi-lobe filters (and, in particular, those with high-amplitude negative lobes) offer poor results on this type of source material. There's simply too much ringing caused by the negative filter lobes for this to look good. That's typically not the case with sampled natural image material, however, which doesn't have the aliasing problems that computer-generated text does.

- Dale Adams
 

Nic Rhodes

Distinguished Member
any any thoughts on mixing scaling algorithms? We regularly have cases now where the DVD player scales to 720p and then the scaler / panel does another scaling operation to say 768p using a different algorith as it from a different company?
 

JohnWH

Active Member
I've always taken the view that scaling is best done in one place as that minimises repeated precision changes (and so potentual LSB errors), however its not always practical and i think a lot of people do some very strange and bad things like assuming 1080i ouput from their uscaling video player is better choice than 720p ouput...

Also I'd guess that small scale factor are worse than large (e.g. 720->768) as there probably aren't enough taps in the scalers filter to avoid cyclic errors, although these don't tend to be very visible in natural video.

All imo of course.
John.
 

tryingtimes

Well-known Member
I don't get this
Basically you look at a dvd on a 32" tv and a dvd on a really well set up projector at 7 feet at the same viewing distance and see which you prefer.
I prefer the projector but YMMV. For some games I actually prefer the unscaled version - because that's how it was designed.

Regarding scaling - I know NicholasB has seen this before, but this is a better example than the one in his post for the reasons Dale Adams outlined.
The comparison screenshots are about 2/3 down the page
http://archive.avsforum.com/avs-vb/...35&perpage=20&highlight=building&pagenumber=2

The only time I sigh at the sight of scaling is when the original image is aliased - e.g. DVD subtitles, OSDs, which do, to be honest look horrible when scaled too far.

I run an HTPC and everytime I run DScaler windowed, I'm amazed at how HD it looks (i.e. when it's showing without any scaling) but it's also only about 3 feet wide and it just doesn't envolop me in the same way - it's so easy to get sucked into things when it's filling your field of vision.
 

NicolasB

Distinguished Member
tryingtimes said:
Regarding scaling - I know NicholasB has seen this before, but this is a better example than the one in his post for the reasons Dale Adams outlined.
The comparison screenshots are about 2/3 down the page
http://archive.avsforum.com/avs-vb/showthread.php?threadid=92835&perpage=20&highlight=building&pagenumber=2
That is actually a much, much worse example: it is extremely misleading in precisely the way that this thread is an attempt to prevent. What those images do is compare the image scaled over different pixel sizes.

The reason going from the SD to the HD screen makes it look better is because the pixels are smaller. Whether making the image bigger makes things look more pleasing if the pixels stay the same size is a whole different question.

Those examples illustrate, for example, the difference between an NTSC DVD picture shown full-screen on a 42" 852x480 display, vs the same image shown full-screen on a 42" 1920x1080 display. It's a given, under those circumstances, that the higher-res version will look better if you're close enough to the screen. But I'm interested in the difference between the picture being shown at 852x480 (letterboxed) and 1920x1080 (full screen) on the same display.
 

NicolasB

Distinguished Member
Dale Adams said:
Be astonished, then. Lanczos3 is a just variety of a windowed sinc function. All the algorithms used in DVDO scalers are based on windowed sinc functions for the filter coefficients.
Oh? Cool! :)

By the way, the highly-aliased text example you use is not representative of normal video material.
I carefully chose the font to be one that Windows does a very good job of antialiasing (without, of course, using Cleartype to do it). And, since the upscaled images were created by first downscaling the image, that farther eliminates artificially sharp edges. I'm not suggesting it's an ideal example, by any means, but it's not as bad an example as you're making out, either.
 

tryingtimes

Well-known Member
Hi there
But isn't this comparison really easy to see in any regular AV shop.
If a big screen picture (form a projector for example) doesn't make you go WOW, but a plasma does - your decision is made.
It's not Home Cinema to me personally though.

The scaling images from AVS I posted is a much harder concept for people to grasp which is why I disagree that it's misleading. It shows that enlarging your image can make more detail visable. If you don't like the softening, then that's for your eyes to decide.

I just don't think that many people are hoodwinked into buying 100+" screens when a 32" lcd would have suited them better.
Surely they are shopping for size first and foremost, and then trying to get the best quality solution possible.

There are lots of high-end plasma owners whose jaws drop when they see a film on my setup.
 

NicolasB

Distinguished Member
tryingtimes said:
The scaling images from AVS I posted is a much harder concept for people to grasp which is why I disagree that it's misleading. It shows that enlarging your image can make more detail visable. If you don't like the softening, then that's for your eyes to decide.
It doesn't take a genius to realise that it's comparing a number of images, all of which are exactly the same size. How, precisely, does this model "enlarging the image" to different degrees? :rolleyes: They're changing the size of the pixels not changing the size of the image.
 

tryingtimes

Well-known Member
But you've not taken into consideration the whole of my post - my argument isn't solely based on those avs images. Those just show that upsampling can remove aliasing noise.
My main point is that size increases the physical reaction to the images - you feel more involved and are more attentive.
There are trade-offs, but these are IMO easy to evaluate.
 

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