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Keystoned image is good, but non-keystoned background light is visible

2525 Views 6 Replies 5 Participants Last post by AV_Integrated, Jun 29, 2021

___ld

Discussion Starter · Jun 27, 2021

Hi,

I recently got my Epson 3200 / tw-7000 and I'm pretty happy with it, especially because it allows for a flexible position in the corner of my living room using the 'quick corner' while still providing a nice, large sharp and perfectly aligned image, which is basically what I wanted to achieve

I've noticed however that when it's dark and the image is at its best, then there's a small non-keystoned area around the actual movie I'm watching. It's not as visible as on the illustration I've attached here, but still a bit too visible for my taste. Any suggestions for workarounds to mitigate that effect?

Thanks
Lars

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robbyc30

· #2 · Jun 27, 2021

Black velvet. There are various products you can use. Plain material, adhesive tape, adhesive rolls (like wallpaper). I guess it would depend on how much overage there is and how much you like the look of the velvet. You could just cover the whole front wall with velvet, or just a strip of tape around the screen.

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PixelPusher15

· #3 · Jun 27, 2021

I'm surprised that you have a placement that is outside the limits of the lens shift on the TW7000. Have you tried maxing it out and getting your projector square to the screen?

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b curry

· #4 · Jun 27, 2021

___ld said:
Hi,

I recently got my Epson 3200 / tw-7000 and I'm pretty happy with it, especially because it allows for a flexible position in the corner of my living room using the 'quick corner' while still providing a nice, large sharp and perfectly aligned image, which is basically what I wanted to achieve

I've noticed however that when it's dark and the image is at its best, then there's a small non-keystoned area around the actual movie I'm watching. It's not as visible as on the illustration I've attached here, but still a bit too visible for my taste. Any suggestions for workarounds to mitigate that effect?

View attachment 3148536

Thanks
Lars

The non-keystoned area is the actual LCD image panel.

The difference between the two areas, or the non-keystoned area is lost panel/picture resolution.

In other words, you're not getting full 2048 × 1080p or 4096 × 2160p resolution depending on your source.

If you're using Keystone correction or the "Quick Corner" Keystone feature, you've compromised the best image quality the projector is capable of producing as the projector has re-scaled the image as a trapezoid inside the space of the 3 LCD imaging panels. Some pixels will be squeezed, some pixels will be spread across 2-3 or more pixels, and some pixels will simply not be used. The unused pixels are "blacked out" by the scaling engine but as you've noted, are visible as a difference in contrast depending on the image brightness. Using any keystone correction needlessly introduces artifacts to the image.

The best workaround or mitigation is to level the projector and project an image at a 90° right angle or perpendicular to the projection surface and eliminate the use of any Keystone correction. If this is not possible, you'll need to use some kind of screen masking around the projected image to hide the unwanted area.

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___ld

Discussion Starter · #5 · Jun 27, 2021

PixelPusher15 said:
I'm surprised that you have a placement that is outside the limits of the lens shift on the TW7000. Have you tried maxing it out and getting your projector square to the screen?

I've used both lens shifting and massive keystoning (quick corners). My living room is a bit tricky, so placement where the projector is not placed squared to screeen (which is just a white wall btw.) is key.

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___ld

Discussion Starter · #6 · Jun 27, 2021

b curry said:
The non-keystoned area is the actual LCD image panel.

The difference between the two areas, or the non-keystoned area is lost panel/picture resolution.

In other words, you're not getting full 2048 × 1080p or 4096 × 2160p resolution depending on your source.

If you're using Keystone correction or the "Quick Corner" Keystone feature, you've compromised the best image quality the projector is capable of producing as the projector has re-scaled the image as a trapezoid inside the space of the 3 LCD imaging panels. Some pixels will be squeezed, some pixels will be spread across 2-3 or more pixels, and some pixels will simply not be used. The unused pixels are "blacked out" by the scaling engine but as you've noted, are visible as a difference in contrast depending on the image brightness. Using any keystone correction needlessly introduces artifacts to the image.

The best workaround or mitigation is to level the projector and project an image at a 90° right angle or perpendicular to the projection surface and eliminate the use of any Keystone correction. If this is not possible, you'll need to use some kind of screen masking around the projected image to hide the unwanted area.

Thanks for explaining

I'm aware of the compromised image quality, but to be honest it still looks amazing, especially when watching 4K content and my main goal is to have a projector that's not really actively part of the room in any way when not in use, which has been pretty tricky (I think the XGIMI horizon pro would be awesome, but it's not available in my country) so I feel like this is the closest I've gotten to what I want to achieve within my budget range.

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AV_Integrated

· #7 · Jun 29, 2021

The only real solution if you can't get good placement due to room limitations is getting the area where the image panel is overshooting as dark as possible. The above recommendation for black velvet is certainly a 'best answer'. But, if you have a local fabric store or can buy online, you should look for similar light soak materials which will just make the overshoot disappear.

If you can't really put up a dark border around things to soak up the overshoot, then you may have to live with things.

You could try putting together a small black mask that you hang in front of the lens a bit, but that's not a perfect solution as the edges will be soft and it may be even more distracting.

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