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What's this effect on my projector?
02-27-2017, 03:25 AM
Post: #1
What's this effect on my projector?
Hello everyone, I've been a CRU user and forum reader for years now (yeah, silent majority, haha) and I think only this great community can help me solve this issue I'm having with my projector.

It's an LG PA1000 LED DLP and it's really versatile with CRU, I could overclock it to 1280x800@120hz by using the software, and it even accepts rare refresh rates like 119.88913621364 in case it's needed (no idea what for but it works! xD)

Thing is, in some horizontal movements I've been noticing some "color halo" around some picture edges, as the image it's not only showing motion blur, but also a kind of aquarelle painting effect. I can confirm it's the projector as I've tried several videocards to with it, a laptop, a VGA cable instead of HDMI. Nope, the same.

Here are the pics, I used this testufo link to test it (http://www.testufo.com/#test=photo&photo...0&height=0)

Still image
https://i.cubeupload.com/KG5ad2.jpg

Movement (1920pix/sec for exaggerating the effect, but it's visible even at 120pix/sec in the test, like, a little horizontal speed and the halo appears)
https://i.cubeupload.com/jIyB4C.jpg

In FIFA this color halo is visible in the grass if the camera moves too fast, and you can see that green and red color are like alternating
https://i.cubeupload.com/jEB1LE.jpg

My CRU settings:
[Image: http://i.cubeupload.com/IGbbMT.jpg]

I know that DLP got a rainbow effect by default, I'm sensitive to it and I could easily see it when the projector was set to 60hz, but it vanished when I set it to 120hz. But this is different, or maybe it's a combination between a slow color wheel and a high response time, I'm really really lost. Have any of you experienced something like this? perhaps I'm making a mistake in my CRU settings?

Thank you and greetings from Chile Big Grin
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02-27-2017, 07:12 PM
Post: #2
RE: What's this effect on my projector?
Maybe the color wheel is locked to 60 Hz so you're only getting 2 of the 3 RGB colors per refresh, or maybe it can only handle certain timing parameters so the wheel might not be synchronizing correctly. Try 1280x720 @ 120 Hz with the "LCD native" timing parameters. That should give you the CEA standard timing parameters. If it can't handle that, then maybe it was not made to run at 120 Hz.
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03-01-2017, 06:31 AM
Post: #3
RE: What's this effect on my projector?
(02-27-2017 07:12 PM)ToastyX Wrote:  Maybe the color wheel is locked to 60 Hz so you're only getting 2 of the 3 RGB colors per refresh, or maybe it can only handle certain timing parameters so the wheel might not be synchronizing correctly. Try 1280x720 @ 120 Hz with the "LCD native" timing parameters. That should give you the CEA standard timing parameters. If it can't handle that, then maybe it was not made to run at 120 Hz.

Strangely enough the effect is still noticeable at 60 Hz, less than at 120 Hz but still somehow present. I tried LCD native and the result is the same. The projector supports 1024x768@120 in factory settings for 3D. After using CRU to "unlock" 1280x800, I've ran some tests and they show it's real 120hz, no frameskipping at all, so I guess 120 Hz at the native resolution was just a hidden feature. I've read a lot but I'm still a noob, so maybe this is a reaaally stupid question since I don't know if it makes sense but: is there a chance the projector is just doubling 60hz instead of doing real 120hz even when the frameskipping tests are right? I took some pics with my camera at 1 second exposure and it's good.

I'm also using this page (https://www.monitortests.com/pixelclock.php) to test different VT, HT and pixel clocks, but no difference. Btw, I'm using HDMI, is there any difference between pixel clocks? I don't know if it's better to use the lowest or the highest possible (I can choose until 224MHz, after that the screen is purple).

Thank you for your help mate. Greetings.
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03-05-2017, 10:49 PM
Post: #4
RE: What's this effect on my projector?
(03-01-2017 06:31 AM)DeFierro Wrote:  Strangely enough the effect is still noticeable at 60 Hz, less than at 120 Hz but still somehow present. I tried LCD native and the result is the same. The projector supports 1024x768@120 in factory settings for 3D. After using CRU to "unlock" 1280x800, I've ran some tests and they show it's real 120hz, no frameskipping at all, so I guess 120 Hz at the native resolution was just a hidden feature.
If it happens at 1024x768 @ 120 Hz, then it's probably just a quirk of the projector. I don't know what could cause that kind of artifact other than the color wheel not being perfectly synchronized with the refresh rate, so it could be missing a color every few refreshes. If that's the case, it should show up on the frame skipping test with some squares having the wrong color. If not, then I don't know. If this were an LCD monitor, I would say it almost looks like overdrive artifacts, but that doesn't make sense for a projector.

(03-01-2017 06:31 AM)DeFierro Wrote:  I've read a lot but I'm still a noob, so maybe this is a reaaally stupid question since I don't know if it makes sense but: is there a chance the projector is just doubling 60hz instead of doing real 120hz even when the frameskipping tests are right? I took some pics with my camera at 1 second exposure and it's good.
If it were just doubling 60 Hz, it wouldn't pass the frame skipping test.

(03-01-2017 06:31 AM)DeFierro Wrote:  I'm also using this page (https://www.monitortests.com/pixelclock.php) to test different VT, HT and pixel clocks, but no difference. Btw, I'm using HDMI, is there any difference between pixel clocks? I don't know if it's better to use the lowest or the highest possible (I can choose until 224MHz, after that the screen is purple).
Just use whatever works. Lower pixel clocks use less bandwidth, but lower vertical totals will prevent the video card from clocking down when idle.
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04-29-2017, 06:30 AM
Post: #5
RE: What's this effect on my projector?
(03-05-2017 10:49 PM)ToastyX Wrote:  If it happens at 1024x768 @ 120 Hz, then it's probably just a quirk of the projector. I don't know what could cause that kind of artifact other than the color wheel not being perfectly synchronized with the refresh rate, so it could be missing a color every few refreshes. If that's the case, it should show up on the frame skipping test with some squares having the wrong color. If not, then I don't know. If this were an LCD monitor, I would say it almost looks like overdrive artifacts, but that doesn't make sense for a projector.

Thank you for taking the time to reply, ToastyX. I've been testing more things these weeks and I finally came to the conclusion that it has nothing to do with the 120hz refresh rate, pixel clock or whatever. I connected the projector by HDMI to the digital TV decoder, with a 60fps broadcast at 60hz, and this effect is also visible when there's a fast panning scene. I also tested my brother's projector that's similar (another model of LG LED DLP) and the same happens. Anyway this kind of "colorful ghosting" is not extremely noticeable unless you're a maniac like me, so it doesn't spoil any experience so far (I mean, I just noticed it because I was doing motion blur tests, after 2 years of use).

What I haven't tried is a more expensive HDMI cable, both me and my brother use normal ones, but I also don't think it is that because I tested with a VGA cable too with no difference. I hope I can get someday what it is exactly, maybe projectors have their own overdrive artifacts.

Greetings Smile
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