CIA: Constant Image Area - Page 10

Originally Posted by CAVX

Why exactly are you selling your BenQ?

Originally Posted by CAVX

umm, you think? Have another look at that chart you posted. And the letters S M P T E mean anything to you?

Originally Posted by CAVX

Interesting given our rooms (throws) are about the same size. I've got the W5000 working for CIH

Originally Posted by CAVX

So what exactly is the problem?

Originally Posted by CAVX

Not at all. I'm satified with the image height in my current room I accept that if I want a bigger image that I need a larger room or I just sit closer

Originally Posted by CAVX

I've got something better than a cookie.

I'VE GOT CIH!!!

Originally Posted by CAVX

What this proves if that CIH can work in small spaces as well as large rooms.

Originally Posted by Art Sonneborn

Maybe but CIA is hard to find ,can you name a few theaters using this ? I can't find them.

Oh and by the way dismissing me isn't a valid technique in argument.

I agree that CIH is the best way to project in the home and likely is the default way to project commercially adds validity to CIH. CIA has significantly less legs to stand on IMO.

Art

Originally Posted by CINERAMAX

Lon, I had never thought of the need for equal area on cinemascope and hdtv, interesting point.

The current and upcoming slate of Blue Ray movies is just a sampling from the bottom half of all the great films out there, I am very dissapointed in the quantity of quality offerings. Turner Classic Movies, and Fox Movie Channel one day will start transmitting in full hd. At that time I suspect you will see a scramble for CIA.

Congratulations for being ahead of the pack.

Originally Posted by Bjoern Roy

As i explained above, i am using a 'constant area' methology for my screen. To show the difference of the 3 common widescreen ratio concepts, i prepareded some images. For simplicity, I only used the two most popular widescreen ratios: 1.85:1 and 2.35:1, while in reality i implement the concept for all ratios 1.33:1, 1.66:1, 1.85:1, 2.35:1 and 2.76:1.

1) 'constant width' on a 16x9 screen. This is the most common concept. The problem with this popular setup is that you either:
a) sit at a distance so that 1.85:1 movies look perfect, but then 2,35:1 movies look somewhat puny and loose a lot of their impact.
b) or you sit at a distance so that 2.35:1 movies look perfect, but then 1,85:1 movies look somewhat intimidating, a bit too large.

2) 'constant height' on a 2.35:1 screen. I prefer this setup over 1 by a long shot. Its like in the theaters, scope movies open up wider to give a more epic, eh, scope. I used this methology for a long time. I either adjusted my seating distance so that 2.35:1 look immersive, but then 1.85:1 movies looked a bit tiny, although acceptable. Or i adjusted my seating distance so that 1.85:1 look just right, but then i ended up with a seating distance of a lot closer than 1.5 times screen width for 2.35:1 movies, which is IMHO simply too close for DVD , let alone other sources. For HDTV material, this would probably be the ideal setup.

3) So i decided to go the 'constant area' route, which projects every format so that the same area on screen is occupied. This results in having a almost equal size-sensation, no matter what ratio you display. I am very happy with the results, because i don't get 'somewhat small' feeling for any format, like i did with the other methologies. The actual sizes of the different ratios in my setup are described in an earlier post.

Very few people operate their FP system in a 'constant area' scenario, perhaps because it is mandatory to have a real 4-way masking system to implement it. If done right, its amazing.

Hope this is insightful to people who are in the planning stages of a HT room (and others as well, of course). Feel free to ask whatever questions you have, here or through email.

Best regards
Bjoern

Originally Posted by Bjoern Roy

Alan,

i just love 2.35:1, too! Since most of my viewing is done in 2.35:1 these days anyway, my screen is in that ratio most of the time anyway. And i wholeheartly agree, entering my HT with the screen in 2.35:1 mode gives me goosebumps every time. My theater is designed to give the perfect experience for 2.35:1 material. So its not different to a 'pure' 2.35:1 screen in that regard. Its just that i use a few percent more screen area for movies in the 1.85:1 ratio than you would with a 2.35:1 screen. You would have to try it to get a believer in this. In a movie theater its quite different for me, because i usually sit at 1 times screen width or closer, so no matter what ratio the movie is, its HUGE

Originally Posted by CAVX

Given the added expense Cinema would have to cover (zoom lens for smaller ARs and 4 way masking systems), you have wonder why they would even bother. There are cinemas on the Gold Coast that use an apperature plate to try and even up the difference in ARs, but all this does is limit the width of Scope from 2.39:1 back to about 2.0:1. They still use the 2x anamorphic lens for Scope films, but they can now have a taller image in a given width cinema. No one (except me) seemed to notice, so I guess ignorance is bliss in this case. It does not make it right and given the strong lean towards CinemaScope in modern film, I can only hope that they will reduce the image size slightly vertically to allow the full Scope width to be projected?

Originally Posted by Bjoern Roy


Hi folks,

the quotes below are from a fellow HT freak, who contacted me about my setup. I will post the answer here for those who might be interested. There is also a more detailed explaination of my 'constant area projection' methodology. Have fun.
____________________


Exactly! 117" width x 42" height for 2.76:1 content.


If you have a 4-way maskable screen it kinda doesn't matter how large the screen is behind the masks. The important thing you mention is that the screen has to have the width of the widest ratio film. For height, a 4:3 screen would be a lot too tall. Since the unused screenspace is masked anyway, it doesn't really matter, though.

Lets assume 2 practical scenarios here.

1) Full blown Constant Area scenario (ultimate nerd alert)
You do care for 2.76:1 movies a lot and want to use the constant area scenario for ALL formats, including 2.76:1. Then the minimum screen ratio surrounding all formats is 1.92:1. For example in my case: screen width is determined through the widest ratio 2.76:1, thus 117 inches. Screen height is determined through the tallest ratio 1.33:1, thus 61 inches. 117" / 61" = ~ 1.92:1. It would not make much sense to actually buy a screen in a 1.92:1 ratio, though. You would simply buy a 117' wide 1.77:1 or 1.85:1 screen and have an inch or two unused above and below.

I would suggest to implement these ratios in this full blown configuration: 1.33:1, 1.66:1, 1.78:1 (or 1.85:1), 2.35:1 and 2.76:1. All of these modes would use the same area on screen.

You could also implement 1.37:1, but thats too close to 1.33:1 to be worth the effort. Simply use the 1.33:1 mode and narrow the vertical masks slightly if a transfer is actually properly framed to 1.37:1.

Same with 1.78:1 which isn't even a real format. Having a mode for 1.78:1 AND 1.85:1 is also not really worth the effort. The two are VERY close, so just choose either one. I would suggest 1.78:1. Most 1.85:1 transfers are actually framed at 1.78:1 anyway. Simply use the 1.78:1 mode and narrow the vertical masks slightly if a transfer is actually properly framed to 1.85:1 like Starship Troopers.

2) CA 'light'
Its kinda silly to take 2.76:1 movies into account if you don't have many, if any at all. So you could simply use the modes listed in 1) but without an actual 2.76:1 mode. Then you would watch a rare 2.76:1 presentation in you 2.35:1 mode, and again, narrow the vertical masks slightly to mask the letterboxing.

In this scenario, the minimum screen ratio surrounding all formats is exactly 1.78:1, what a nice coincidence! Or maybe this is why they came up with 1.78:1 in the first place?

To clarify: The screen width needed here is determined through the widest ratio 2.35:1, in my case 108 inches. Screen height is determined through the tallest ratio 1.33:1, thus 61 inches. 108' / 61' = ~ 1.78:1. So you could simply buy a 1.78:1 screen. Good for resale value, too.

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I prepared another figure to show again how the different scenarios actually look like:

My preference is from left to right.

I already posted a comparisson in a post above with pics comparing TS2 and Twine, so these comments here are just to further clarify these comments and bring the other formats into the discussion. I will include the pics again for convenience:

1) Constant Area
Pros: all ratios seem to have the same "size". None of them are too small or too big. You simply adjust your seating distance to you liking for, lets say, 2.35:1 movies and the others all look perfect too.
Cons: variable 4-way masking needed

2) Maximum Size within 2.35:1 screen
Pros: easier to implement than 1). Except for 2.76:1 material,only horizontal masking needed (curtains). 2.76:1 material would be slightly letterboxed and if no vertical masking is available, wouldn't have the full impact of a properly masked presentation. The need for 100% masking can't be stressed enough, really!
Cons: All formats smaller than 2.35:1 are too small for my liking, but as i already said, i still prefer this over the 16:9 solution. To make a 2.35:1 screen work, you adjust your seating distance so, that you sit a tad too close for 2.35:1 movies (lets say 1.3-1.4 times screen width, instead of my 1.5 times recommendation). Then 2.35:1 is slightly too big and 1.85:1 is slightly too small, but all in all, both look great. 1.33:1 is outright puny! But you could argue 'who cares'? 1.33:1 is not meant to be epic anyway. If you watch a lot of 1.33:1 television stuff, this might be a problem for you. But i would argue that most 4:3 material (e.g. NTSC broadcast) is terrible in quality anyway and not worth getting projected too big.

3) Maximum Size within 1.78:1 screen
Pros:Very common, pretty much straight forward.
Cons:You still need 4-way masking! So you could go the extra mile for 1) if at all possible (projector memories etc...) In scenario too, you could adjust your seating so that its a compromise between 2.35:1 and 1.85:1, just like in 2). Only that now 2.35:1 look somewhat small and 1.85:1 somewhat big, which i simply don't like. So the only other option would be to adjust seating so that 2.35:1 looks perfect, but then 1.85:1 movies look enormous.

4) Constant width in 4:3 screen
Pros: If you don't watch movies, this is great
Cons: Well, better don't get me started.

I really tried to keep it short. REALLY!

Best regards
Bjoern

Originally Posted by CAVX

And this applys to CIH as well but LilGator says on page 1 that he can't or doesn't want to move his seating. It is all about image height, not width.

Originally Posted by Bjoern Roy

'Constant area' projection is IMHO by far the best methology, because the brains 'size sensation' is perceived through area, not width or height.

Originally Posted by Bjoern Roy

Cons: All formats smaller than 2.35:1 are too small for my liking, but as i already said, i still prefer this over the 16:9 solution. To make a 2.35:1 screen work, you adjust your seating distance so, that you sit a tad too close for 2.35:1 movies (lets say 1.3-1.4 times screen width, instead of my 1.5 times recommendation). Then 2.35:1 is slightly too big and 1.85:1 is slightly too small, but all in all, both look great.

Originally Posted by Art Sonneborn

Nor do I, you are the one using the THX certification as a means of vaidating CIA.

Originally Posted by Art Sonneborn

You mentioned a 50:50 split in an earlier post which is just false.When I said that my local theaters were CIH you said that my local theaters don't mean all the theaters in the world or some such. I know better but I was willing to go the extra mile to show you. Instead of admitting that you were wrong you ridicule my efforts.

Art

Originally Posted by Art Sonneborn

Here it is. I could call every cinema in the world but I don't think that will be necessary.

Art

Originally Posted by Art Sonneborn

The difference is you stated that my contention that CIH was by far the most commonly used technique was not adequately supported ,it is.

Art

Originally Posted by HogPilot

Exactly how would masking for a CIA FP setup be easy? A 4-way masking system can be either very expensive and relatively easy, or cheap and lots of work, but certianly not both.