HTPC to the pixel alignment rescue?.. - AVS Forum
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post #1 of 14 Old 10-03-2013, 11:07 AM - Thread Starter
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I ran across this post the other day and it struck my interest... 

 

Or the next version will contain a high quality convergence/panel alignment correction algorithm for 3-chip projector owners, which I hope/think will be of higher quality than what the projector manufacturers (e.g. Sony) currently offer. More to come in future versions...

 

http://www.avsforum.com/t/1485929/how-to-calibrate-video-output-of-htpc#post_23762571

 

Since I already use a PC (OpenELEC/XBMC/WMC) I'm wondering when it will be released. :) 

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post #2 of 14 Old 10-03-2013, 11:33 AM
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if this is a digital solution that doesn't physically move the chips, why would it be specific to 3-chip DLP's? would this be even better for single chip or LCD/Lcos projectors that don't generally give you any alignment fixes? or is it just so rare that anything other than 3-chip DLP's need the colors realigned?

Displays: Samsung PN64F8500/JVC X35
AVR: Pioneer VSX-1018AH, 5.1 audio
Sources: HTPC(Mediabrowser), PS3, XBOX360, Wii, Sony DVP-CX995V
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post #3 of 14 Old 10-03-2013, 12:32 PM - Thread Starter
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I'm guessing 3-chippers are simply the most obvious target and others could benefit. I'm also presuming it would/will offer multi-zone adjustments and that's where I'm really interested. Even if it's only in one pixel increments (not sub-pixels) I would find it very valuable... or should I say my JVC would. :)

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post #4 of 14 Old 10-04-2013, 12:42 AM
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Wow. Just WOW. Madshi is a wizard. Can't wait for the new version of madVR.
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post #5 of 14 Old 10-04-2013, 05:40 AM
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Quote:
Originally Posted by Charles R View Post

Since I already use a PC (OpenELEC/XBMC/WMC) I'm wondering when it will be released. smile.gif  

But madVR doesn't work in any of those. That's really my biggest problem with it, well not madVR or Madshi's work (which are both awesome) but with using a PC/HTPC, it's just so fragmented. madVR is awesome, you can do CMS, high quality scaling, I see he's added a dering filter now, but it's only useful in the apps that can use it, and that excludes linux (OpenELEC), XBMC, Windows Media Center, PowerDVD, WinDVD, TMT, since they all use their own video renderer which can't be changed (well XBMC might work with DirectShow rendering). So unless you can use a madVR compatible program for everything you watch, you won't get the same calibration/quality for everything.

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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post #6 of 14 Old 10-04-2013, 06:48 AM
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Just FYI, you can set up XBMC to use MPC-HC (with madVR) as a default video player.
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post #7 of 14 Old 10-04-2013, 07:01 AM - Thread Starter
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Originally Posted by stanger89 View Post


But madVR doesn't work in any of those. That's really my biggest problem with it, well not madVR or Madshi's work (which are both awesome) but with using a PC/HTPC, it's just so fragmented.

 

PC based is both a blessing and a curse. I can easily switch to a supported player with little or no additional cost.

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post #8 of 14 Old 10-04-2013, 08:17 AM
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PC based is both a blessing and a curse. I can easily switch to a supported player with little or no additional cost.

Not always, if you're using WMC for TV, you can't just switch to a different player for TV. Likewise if you want to watch a Blu-ray disc (not ripped) and have menus you can't just switch to a different player. Netflix, Amazon, etc.

See what an anamorphoscopic lens can do, see movies the way they were meant to be seen
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post #9 of 14 Old 10-04-2013, 10:26 AM
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Oh well, normally I manage to keep my mouth shut until a new algorithm is ready for release before I talk about it. But I couldn't resist this time. Since the cat is out of the bag now, anyway, I can just as well post a few more details, so here we go...

I've read multiple times now that Sony's convergence / panel alignment feature results in pink (or multi-colored) discoloration in specific test patterns. It was on my to do list for a long time to add panel alignment / convergence correction to madVR, and so I wondered *why* the discoloration would occur. And after some tests I found out. Here are some test images:

original test pattern ---> correction in gamma corrected light

The corrected image is a result of my own panel alignment / convergence correction algorithm, by using gamma corrected light (which is what movies are usually encoded in) to "realign" the green channel. The red and blue channels are left untouched. In the corrected image you will see the typical pink discoloration. I think that this is probably what Sony users are seeing when using the Sony projector panel alignment feature? The cause of the discoloration is that the processing is not done in linear light, as it should be.

Of course madVR will use linear light processing. Since your computer monitors (which you will probably use to look at these images) are probably not properly calibrated, I've created a few different images now, with different gamma values:

linear light correction, with gamma value: - 1.8 - 1.9 - 2.0 - 2.1 - 2.2 - 2.3 - 2.4 - 2.5 - 2.6 -

One of them should be neutral without noticeable discolorations on your display.

FWIW, the main purpose of this feature will be panel alignment correction for 3-chip projectors (doesn't matter if it's DLP, LCD, LCoS or whatever). But the algorithm should also be able to correct chromatic aberations caused by non-perfect lenses. So it might also be helpful for some single chip projectors.

This feature may result in a small loss in sharpness, though. So it will be to everyone's personal judgement whether using the algorithm improves overall image quality or not. That might also depend on the exact correction necessary for any given projector. E.g. sharpness loss will be biggest if a channel needs to be corrected by 0.5 pixels. Correction by 0.1 or 0.9 pixels costs much less sharpness than correcting by 0.5 pixels. If convergence differs for the 4 edges of the screen, sharpness loss will also vary across the screen, depending on whether correction will be nearer to 0.0 or to 0.5 for each separate pixel.
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post #10 of 14 Old 10-04-2013, 11:32 AM
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You don't stop surprising us, madshi. I really hope that works.
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post #11 of 14 Old 10-04-2013, 12:09 PM - Thread Starter
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Quote:
Originally Posted by stanger89 View Post


Not always, if you're using WMC for TV, you can't just switch to a different player for TV. Likewise if you want to watch a Blu-ray disc (not ripped) and have menus you can't just switch to a different player. Netflix, Amazon, etc.

 

I don't know of anything that's always. However you can view WMC recordings including Live TV with XBMC. Other players will play its files via various methods including native support. Similar options for the others... bottom line the blessing is probably greater than the curse.

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post #12 of 14 Old 10-04-2013, 12:18 PM - Thread Starter
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Quote:
Originally Posted by madshi View Post

Oh well, normally I manage to keep my mouth shut until a new algorithm is ready for release before I talk about it. But I couldn't resist this time. 


Thanks. That was the goal of starting this thread... :)

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post #13 of 14 Old 10-04-2013, 01:01 PM
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Originally Posted by Elix View Post

Just FYI, you can set up XBMC to use MPC-HC (with madVR) as a default video player.

Yeah, but then you lose the ability to resume watching where you had previously stopped it, along with per-movie subtitle settings (or or off on a per-movie basis), etc. I was never really satisfied using an external player with XBMC.
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post #14 of 14 Old 10-04-2013, 01:09 PM
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Yeah, but then you lose the ability to resume watching where you had previously stopped it.
Really? Did you try turning on history settings in MPC-HC?
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