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Blending with a PC
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Joined: 20 Jun 2007
Posts: 362
Location: Illinois

PostLink    Posted: Thu Dec 03, 2009 12:48 am    Post subject: Reply with quote

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I've written code in C, C++, and .net for several years. I would certainly be able to test this out per your requirements on my 2 marquee 8500's. I posted for this type of software several years ago for PC blending to see what interest it might generate. The return profit was not there for the development here at Curt's site. I still have the code floating around somewhere for my application. I used 2 Nvidia 3000 series cards with framelock/genlock and 2 pc's at the time. These cards came with a blend feature which many are aware of, but Nvidia never completed the driver implementation for a seamless blend.

I am glad you chose MPC-HC as the player for the app. If I am correct, the code is based on the Directx SDK. I have a couple older boards that I could put together with a quad core and install the AGP 3000 cards to test. Both have DVI (RGB) out with Moomie cards for the test. Madvr is the best render that I have used on the PC so far and it would be great if this could be implemented to work with it.


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Joined: 09 Aug 2006
Posts: 5

PostLink    Posted: Thu Dec 03, 2009 1:29 am    Post subject: Testing Reply with quote

Hey guys,

I've got a couple of Marquees, an nVidia card, and a Canon DSLR. I've got the projectors linked with RS-232 for the communication and control. I'd be happy to test out this color calibration software, and the blender too. I have some time this weekend, let me know.

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Joined: 04 May 2007
Posts: 10
Location: Telford, UK

PostLink    Posted: Thu Dec 03, 2009 9:05 am    Post subject: Reply with quote

Hey folks, haven't been on this site for a while but was pointed here by MikeEby from a blending thread on AVS.
I've had a blend setup for around 3 years or so, with a pair of Barcos 801s projectors using VLC as the blender.

Its very interesting to see that another solution is in the works, but I am also wondering whether you guys have looked at the VLC blend? I'm curious to know what wasn't good enough about the VLC blending to want to start working on a different software solution?

I seem to remember that when the VLC blend was first discussed, some people found that because only computer based source material could be used (i.e. no blending of HDTV broadcast etc), they wanted to persue a hardware blending solution instead, and then the software based blending discussion kind of fizzled out.

Did I read right that there is some auto-colour calibration system using Canon DSLR in the works? Now this would be veeeeeeery interesting, I find that getting the colour calibration and matched grey-scale tracking probably the hardest part about getting the blend seamless.

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Joined: 16 Jul 2006
Posts: 297

PostLink    Posted: Fri Dec 04, 2009 9:19 am    Post subject: Reply with quote

Hi All,

Let me break this out in the 3 pieces I'm working on and their current state:

Blend software

It's a pixel shader plugin that works in Media Player Classic that does the blend. I've improved it a bit since first discussion here and it does:

1. 1:1 pixel mapping assuming you configure it correctly
2. Blend attenuation with a specific gamma value (e.g. 3.4)
3. NEW: Gamma compensation. In my setup I'm finding that my tubes are more like a gamma 3.4 which mean massive low-end clipping (everybody who's had a CRT has experience this, I think... hence all the gamma correction solutions)... Assuming that you KNOW the default gamma of the setup (i.e. the number above, for me it's 3.4) you set the TARGET GAMMA (e.g. 2.22 or 2.5... there are tastes for everything....) and the software will do gamma compensation at the signal level. This is super interesting b/c I am seeing a number of details I could not see and natural-looking scenes (as if you were watching them in a CRT TV) that I haven't experienced before in a CRT FP. I can post this code for all interested.

This software assumes that:

* Projectors are properly setup for a blend setup
* Projectors are COLOR MATCHED following a standard gamma curve (L = V ^ x; where x is gamma)... ACROSS ALL IREs

Marquee G2/DRIVE automatic setup with a DSLR

Anybody who's done blending knows that color matching is the MOST difficult part to get the blend right.... and in my experience BY FAR. This software is now functional (I've used it a lot of times now) and matches the two projectors color-wise remotely controlling the PJ's G2/DRIVE levels while measuring light output of a dark (e.g. 10 IRE) and bright (e.g. 80 IRE) boxes with a DSLR automatically.

The software matches light output at those two points, using very fine G2/DRIVE adjustments (i.e. 12-bit for G2, 8-bit DRIVE). At very low end IRE, one step in the G2 changes the reading... so you NEED this level of control.

Projector color transfer curge (i.e. gamma curve) measurement and gamma equalization

This software takes many measurements of small IRE boxes (from 0 IRE to 100 IRE in as many steps as you want) and measures light output for all for 3 colors for two projectors (or one). I take a lot of time (2 hours or so depending on the steps, etc.).

Once you measure your projector gamma curve, you can now tell the software to create an IDEAL TARGET GAMMA curve and the software will create a 3 10-bit LUTs (for R G B) to get there. These LUTs can now be sent to an NVIDIA card for each head (already done... ATI also has an API for this... If somebody sends me the latest ATI card with Eyefinity support I'll gladly implement this...). These tables COULD be sent to LUT-based gamma correction hardware units. I'm talking to a few companies to see if they are interested. This solution is 100% projector independent, but you need a device (or HTPC) to perform the equalization.

I'm working on a simplified solution so that everybody with a point-and-shoot camera with some minimal hardware support can use this approach. I'm getting a Canon S90 point-and-shoot as a present this X-mas so I'll report after the New Year if/when I complete this.

Let me address some questions:

Why Marquee only? I'm doing this for fun. If you want this done for another CRT, send me a Cine9 or G90 with its protocols... Smile No really....

In addition, the only solution is Marquee dependent is the G2/DRIVE calibration.... the other two are not. I already posted the blender code... you can use it with any other PJ.

Why MPC-HC? Because you can debug/test pixel shaders on the go and the shader programming is so trivial with no learning curve (assuming you can understand C). BUT... doing it with a custom renderer (e.g. a modded version of MadVR) would be a MUCH better idea. Send me a PM and we can get this done easily. I even wanted to hack a miniport display driver to do this... but I don't have that amount of time.

Will I share the code I'll open-source as long as contributors want to extend it and make it more usable.
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Joined: 06 Sep 2010
Posts: 56
Location: Masury, Ohio

PostLink    Posted: Thu Sep 09, 2010 1:21 am    Post subject: Reply with quote

So has anyone gotten this working effectively?
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Joined: 16 Jul 2006
Posts: 297

PostLink    Posted: Thu Sep 09, 2010 6:11 am    Post subject: Reply with quote

I am.
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Joined: 06 Sep 2010
Posts: 56
Location: Masury, Ohio

PostLink    Posted: Thu Sep 09, 2010 6:34 am    Post subject: Reply with quote

Is it working well? Do you think it performs as well as doing it with hardware?
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Joined: 16 Jul 2006
Posts: 297

PostLink    Posted: Thu Sep 09, 2010 8:56 pm    Post subject: Reply with quote

Yes - but it only works for PC based sources using that specific video player. It's all I use it for now; I use the DVX8022 for XBOX.
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Joined: 13 Feb 2008
Posts: 158

PostLink    Posted: Sat Jan 08, 2011 10:16 am    Post subject: Reply with quote

Is the DSLR shooting automatic? That would be very cool, just go to toilet and the pj finished colour balance.
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the big E

Joined: 20 Apr 2013
Posts: 1919
Location: speedwell Tn.

PostLink    Posted: Sat May 25, 2013 5:48 am    Post subject: Reply with quote

guys i have a few digital projectors i may try this with windows 7 i have a dual dvi video card(its a ati high end pro card) i may tinker around with windows 7 and see if media center works over the blend(pc techie with a lot of hardware)
crt king of black
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Joined: 22 Mar 2006
Posts: 1614
Location: ottawa, canada

PostLink    Posted: Wed Sep 04, 2013 12:50 am    Post subject: Reply with quote

so...after all this, is there any external software I need or can get to accomplish this?

WHile it does seem fairly time intensive...winters are long up here...

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Joined: 09 Nov 2008
Posts: 6319
Location: Australia

PostLink    Posted: Thu Dec 26, 2013 2:35 am    Post subject: Reply with quote

You can do it all pretty easily from the nVIDIA control panel now and any programs will work fine across as many monitors as you have outputs.
Barco CineMAX, 120" OZ Theatre Majestic 16:9 screen, H/K AVR 7.1...

RUNCO DTV991 LC ( NEC XG 852 LC ) 100" 4:3 screen, H/K AVR 5.1...
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