Projector 4:3 and 16:9 question (1 Viewer)

[AdamP]

It was always my understanding that a projector could display each of these flawlessly since ther was no "box" to project onto. I read that if you get a widescreen projector and the signal is 4:3 then the projector will have to stretch the image a litle or there will be bars. Is this correct? I already have a widescreen rear projectin TV and I know all about the different ways to stretch a 4:3 signal, but why can't projectors fix this and do both? (might be out of the realm of this forum)

 

[ChrisWiggles]

Dealing with different aspect ratios will always have some kind of bar or masking issues. There is nothing inherently different to an RPTV than a FP, so I guess I'm a little confused by your question...

An RPTV can display each of these "flawlessly" too. FP is the same way.

 

[Jack Gilvey]

If you have a screen of fixed dimensions onto which you wish to project multiple aspect ratios correctly, there will, at times, be "unused" screen area (either to the sides, or at top and bottom). You can "mask" these "unused" areas so as to make them disappear. I guess this would be considered "fixing" them.

 

[ChrisWiggles]

By the exact same token, an RPTV has a fixed screen, that should be masked. I'm not seeing any difference at all.

 

[Jack Gilvey]

Agreed.

 

[AdamP]

Ok, so there's no difference between a projection TV and a projector. I thought you could do away with the black bars with a projector since there was no box. I'm asking becase I thought I could buy a really wide 4:3 screen to project a full size 4:3 picture as well as project a 16:9 picture and get the best of both worlds.

So, if I get a 16:9 projector and a 4:3 screen, the 4:3 signals would project a relatively smaller 4:3 picture. And if I got the 16:9 screen, the 4:3 signals would take up the middle of the 16:9 screen and not use the outer wide bands unbless I use the stretching.

Damn, I was hoping a projector would be able to project both the 16:9 and 4:3 in the larger sizes, but it can't. damnit, why not?

 

[ChrisWiggles]

If you get a 4:3 screen and a 4:3 projector, widescreen will have to be letterboxed on the projector, and hence on the screen. Masking down to whatever that AR is, is the desired route, because you will have unused screen space on the 4:3 frame, of which only part is being used for 16:9 or wider AR. There will always be the bars issue, and variable masking is the best way of eliminating those, by in essence altering your screen shape to match the picture.

 

[Jack Gilvey]

Huh? It's either "really wide" or 4:3...there's the geometry again...

 

[AdamP]

But what's in a projector that makes it 16:9 or 4:3? and why can't it have both of these?

 

[ChrisWiggles]

The chip itself has a particular aspect ratio. You can in essence alter this with an anamorphic lens if you want to use the entire panel's resolution for an AR that doesn't fit the panel, otherwise you are losing parts of the panel's resolution to bars.

 

[Michael TLV]

Greetings

Are you asking for a projector where the dlp chip or LCD chip magically changes shape to match the material that you are feeding it?

I think you want a holodeck ... and you want it now.

Either that or a projector with a bunch of different anamorphic lenses that slide into place for each of the different aspect ratios out there.

one for 1.33; 1.66; 1.75; 1.85; 2.00; 2.15; 2.20; 2.35; 2.50; 2.76; 3.00

Man, that's a lot of lenses ... and at $2000 a pop per lense ... that's $22000 in optics and a machine that will change these lenses for you.

Regards

 

[Darren Haycock]

I'm a little confused on the matter myself. But let me make sure I understand. It is possible for a 16x9 projector to change aspect ratios like a widescreen tv, correct? For example, 4x3 material will have bars on the left and right sides, or heaven forbid you could stretch it. Am I right in thinking this, or is this option not available on projectors?

 

[Scott Dautel]

Youse guys are really confusing Adam & Darrin ... we were all tech-novices once!
I'll take a shot at explaining it to them so as to tell them what they wanna hear ...

First example ... the InFocus X1 Front Projector (DLP):
This projector has 800 [wide] x 600 [high] pixels on the chip. Thus, this is a 4:3 "Native" Front Projector
there are 3 settings ...
1) 4:3 Mode - uses all the pixels
2) 16:9 Mode - shuts off approx 75 pixel rows top & bottom, thus projecting 800 x 450.
3) Native Mode - uses approx only 600 x 450 pixels to display 4:3 images.

So, you ask ... why would anyone use "Native Mode"? The answer is quite simple. lets say I order a fixed screen 80" x 45". This is a perfect 92" diagonal, 16:9 aspect ratio screen. When I watch Spider-Man on DVD (OAR: 1.85:1), I've set my projector up to "fill the screen", since 1.85 is VERY close to 16/9 (1.78). When I want to switch to regular cable (4:3 AR), I'll flick one button and jump to Native Mode". Now the image fills my screen vertically (45"), but the sides are cropped, using only 60" horizontally. This is still huge image.

If I were to go to full 4:3 mode, the projected image would actually be larger (taller) than the screen ... and nobody wants that atrocity.


Example 2 - The InFocus 4805:
This projector is "16:9 Native", since the DLP chip inside contains 854 x 480 pixels. If you are mostly watching widescreen DVD's, this is an even better option, since 854 x 480 (progressive) perfectly matches the resolution that is encoded on the DVD. This means the computer inside the projector does not have to "rescale" the image.

The same examples go for use of a 16:9 AR screen, the advantage is nthat most of the time you dont have to scale down the image to fit the pixels of your projector.

Now pay attention ... here's where it all comes together ... In all of the above examples, you can make the screen any size you want (within reason and according to PJ throw distance and zoom capabilities). Since I made my own screen for ~$25 (hangs from the ceiling), I could have easily made 2 screens ($50) & swapped them out depending on what I chose to watch. You can make as many screens as you want ... and ALWAYS have a GIANT image that ALWAYS fits the screen; ... and you CAN'T do that with a RPTV!

Scott

 

[Jack Gilvey]

You're evidently correct, although it seemed like basic geometry and nothing all that techie. Rather like when someone posts in the DIY forum: "I don't know anything about subwoofers...how do I figure the volume of a sonotube?"

 

[RomanSohor]

Let me just chime in with one thing...

I have a 4:3 projector, and my screen is an 8' wide pull down (not a big fave of the board, I know, but it was FREE and brand new to boot!), so when I watch 4:3 sources, my picture is 8' wide and 6' high... pretty much floor to ceiling in my new theater room, when I watch WS DVD's, I have my DVD player set to 16:9 mode, and by pushing a button on my remote, it squeezes the image to make it look right. This looks a little better than my DVD player in 4x3 mode, I am assuming because I am sending more resolution to the projector that way. Now, yes I have black bars, but my image is still 8' wide... my room is only about 11' wide, so I doubt if I had a 16:9 projector & Screen it would be any wider. I actually kind of like it, because I can have the absolute biggest picture possible for all types of material. Watching The Beatles play Shea Stadium in full life size with DTS on Anthology today was AWESOME

I don't bother with masking because my room gets really dark, and the black bars don't annoy me enough for it to be worth the effort of trying to figure out how to mask a pull down screen.

I have also used some projectors with 16X9 modes in their set up (ie: select your ratio, 16x9 or 4x3) and it seems like they do the same thing my projector does - because when I set up a DVD player to 16X9 mode, I just see a 4x3 image in slightly higher quality than a letterboxed 4:3 image... I've never used any of the Home Theater kind of projectors most people have here, since I work with Instructional Technologies, most of my work is done with ultra bright (by HT standards) Epson LCD's, and an occasional Dell DLP.

 

[Michael Pineo]

A visual explanation might help here. Here is a quick gif file I created that shows how 4:3 and 16:9 images look on different display types. I didn't have time to create the different aspect ratios, but this will give you a rough idea of how the different shaped panels will display different aspect ratios. Click on this link to view it.

The top row shows a native 4:3 device (like an InFocus X1) and the bottom row shows a native 16:9 device (like a Panasonic L300U).

MikeP

 

[Torgny Nilsson]

I do the same thing as RomanSohor. I like classic movies and modern movies equally. I decided that I would get the best of both worlds by getting a native 4x3 projector and an 8' wide and 6' tall screen. That gives me the largest possible 4x3 image and my widescreen image is still about 4' tall and 8' wide. While I understand that I am apparently losing some resolution when viewing widescreen movies, I can't see any difference when actually looking at the picture.

 

[Matt-Z]

Hi, I'm new, and now I'm confused. When we compare the two aspect ratios of say the X1 and 4805, are we in essence comparing a widescreen tv with a standard one? Meaning with 4:3 you have black bars top and bottom for widescreen stuff; and on 16:9 you get them on the sides for full screen stuff. I always thought that widescreen tvs were stupid as long as they were still nearly as wide as my 54" 4:3. Why wouldn't I prefer the same size picture ws but with black bars AND have the giant full screen. Watching fs stuff on my friends average ws set is equivilant to like a 19" screen! Right? So Should I think the same thing relative to projectors? I was under the impression that the 4805 is basically the same as the X1 only wider in terms of pixels. What is the result of this with a non anamorphic source such as laserdisc? Ok, wait, wait, wait. I'm making myself even more confused. Here's my question...If you had these two projectors on in the same room, and pointed them at the same blank wall from the same distance, would the 16:9 fit inside the 4:3 or would the 4:3 image be inside the 16:9? Now boiling it down, would the 4:3 be as wide as the 16:9 only taller, or would the 16:9 be the same height only wider? Yes, that is my question. I have more but I think I should see how this flies first. Well, maybe just one more. Ok, my current understanding is this, please correct me wherever I need correcting, if I project a 4:3 source on the x1 and on the 4805, the images will be the same size. However, the 4805 will have additional black bars on the sides. Is that right? I hope it is because that's what I want. Now the question that begs asking is what do you do when you have non anamorphic widescreen resulting in black bars all around?