Projector 4:3 and 16:9 question

AdamP · 08-13-2004, 10:16 AM

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 · 08-13-2004, 01:19 PM

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 · 08-13-2004, 02:52 PM

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 · 08-13-2004, 03:33 PM

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 · 08-13-2004, 03:53 PM

Agreed.

**HTF Ads**

AdamP · 08-14-2004, 12:01 PM

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 · 08-14-2004, 12:10 PM

Quote:

but it can't. damnit, why not?

Because aspect ratios are by definition different shapes and sizes.

The only way to deal with this 'prefectly' is to have a screen that changes shapes with the different AT. The way to do it right is to have a screen with variable masking, which you can even do on an RPTV if you want. The masks adjust(manually or automatically) to the particular AR you are watching, leaving no "bars" on the screen, since they will be covered with masking.

Projectors especially, IMO require proper variable masking for the best viewing, since if you are running an AR that is not your basic screen AR, then you will have viewable greyish bars that will be lit up outside the picture area due to light spill from the projector, a digital projector's inability to produce black, and light spill from the room.

Quote:

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.

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 · 08-14-2004, 07:47 PM

Quote:

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?

Simple geometry...as was explained.

http://www.thedigitalbits.com/articl...reenorama.html

Quote:

I'm asking becase I thought I could buy a really wide 4:3 screen...

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

AdamP · 08-16-2004, 03:56 PM

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

ChrisWiggles · 08-16-2004, 04:24 PM

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 · 08-16-2004, 04:30 PM

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 · 08-16-2004, 06:41 PM

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?