Achieving different aspect ratios with a video processor

edthom

Novice Member
Hi, I have a basic cinema set-up in our converted attic and because we have a much wider room compared to its height (due to the sloping ceiling) I use a home made cinema scope screen. I currently have my Optoma projector zoomed so that it is set to 2:39:1 (with black bars top and bottom overhanging the screen masked by black felt) which works fairly well and when I play 16:9 content, I go through the projector menu and use the digital zoom to reduce the size of the image, roughly fitting the screen obviously at a reduced size. My question is, in order to have a similar one button push to change aspect ratio, can I use a video processor (I’ve seen a Lumagen XS-3D Video processor for sale) and will it be as good as if not better than my current zooming image smaller.

I read that using a scaler in this way reduces the resolution of the 16:9 aspect but I don’t really understand why?

Thanks
 

mb3195

Distinguished Member
yes you can, you dont even need to do it with a push of a button, you can select an auto aspect option which will change it for you, very helpful on cinemascope screens.

check out this video on how to do it.

 

mb3195

Distinguished Member

dhts

Active Member
I read that using a scaler in this way reduces the resolution of the 16:9 aspect but I don’t really understand why?

So I think the maths goes like this....

Even though you're showing a 16:9 image, the projector is still zoomed as if it was showing your scope films, so it's projecting a black bar above and below the screen.

So the real film picture with stuff on it is the same height it would be if you were showing a scope image, so around 800 lines of resolution ( a scope image is something like 1920x800 depending upon your how you define scope). The scaler has scaled it down from 1080 to 800 to fit the screen as your projector is zoomed out as if it was showing a scope film).

So your 16:9 image is something like 1422 x 800 rather than as you currently have it 1920x1080.

One way to think about that is you've lost around 25% of the lines of resolution. However you've also lost a similar amount of vertical resolution.

A 1920x1080 image has 2,073,600 pixels, your scaled 16:9 image has only 1,137,600 pixels so around 55% of what you had.

Depending upon how close you're sat this may or may not be an issue.

If you want to dig deeper you can also consider brightness. Using the scaler will make the image less bright than a 1920x1080 image but on the plus side it will be the same brightness as when you're watching scope.

Hopefully someone will jump in if I've screwed up the maths....
 

kenshingintoki

Distinguished Member
So I think the maths goes like this....

Even though you're showing a 16:9 image, the projector is still zoomed as if it was showing your scope films, so it's projecting a black bar above and below the screen.

So the real film picture with stuff on it is the same height it would be if you were showing a scope image, so around 800 lines of resolution ( a scope image is something like 1920x800 depending upon your how you define scope). The scaler has scaled it down from 1080 to 800 to fit the screen as your projector is zoomed out as if it was showing a scope film).

So your 16:9 image is something like 1422 x 800 rather than as you currently have it 1920x1080.

One way to think about that is you've lost around 25% of the lines of resolution. However you've also lost a similar amount of vertical resolution.

A 1920x1080 image has 2,073,600 pixels, your scaled 16:9 image has only 1,137,600 pixels so around 55% of what you had.

Depending upon how close you're sat this may or may not be an issue.

If you want to dig deeper you can also consider brightness. Using the scaler will make the image less bright than a 1920x1080 image but on the plus side it will be the same brightness as when you're watching scope.

Hopefully someone will jump in if I've screwed up the maths....


Yup, so you lose resolution and brightness but in return you get seemless switching of resolutions.

It's not really ideal at all.

I think it might be useful-ish in aspect ratio change films which can be irritating.
 

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