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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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Melifluonze
Joined: 25 Nov 2013
Posts: 262
Location: Upstate NY
TV/Projector: 9500LC Ultra
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 Link Posted: Mon Oct 13, 2014 12:50 am Post subject: |
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Yup, I'm committed. I saw Nash's blend and I'm going to have to try it.
All I can say is WOW!
-M
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Dual Marquee 9500LC Ultras, Dual JVC RS600
Focal Aria 5 custom speakers, HT Tuba
We STILL don't need no stinkin' 7.1!
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Melifluonze
Joined: 25 Nov 2013
Posts: 262
Location: Upstate NY
TV/Projector: 9500LC Ultra
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| Link Posted: Tue Oct 21, 2014 6:41 pm Post subject: |
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Ok, so I just ordered an FPGA based HDMI board. I'm going to try to implement the gamma/color adjustments that Nash is wishing for to see if we can get rid of the vertical lines in the blend zone. Life gets in the way though, so it may take a long time!!!
Also, I'm extremely concerned about geometry and linearity, as Nash is... I think this is the biggest problem. If you don't have all areas of the blend zone right on top of one another, there will be differences. This means that for blending to actually work, you have to have the projectors exactly lined up mechanically, electrically, and in any other way, and the images need to stay locked where they are. Any drift for any reason of ANY parameter or location of the image relative to the other = blend zone shows up!
That being said... if you could butt the projector images right next to each other and hold that spacing, then THAT would possibly be the best "blend". You then use the color/gamma corrector to equalize the second projector to the first... If you can't keep the images within one pixel of each other, then blending will fail no matter what you do... By fail, I mean you'll see the blend zone!
It hurts, but I'm starting to think that blending without a blend zone is not possible. There will always be a visible blend zone...
- M
_________________
Dual Marquee 9500LC Ultras, Dual JVC RS600
Focal Aria 5 custom speakers, HT Tuba
We STILL don't need no stinkin' 7.1!
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jbmeyer13
Joined: 03 Dec 2010
Posts: 1135
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| Link Posted: Wed Oct 22, 2014 2:47 pm Post subject: |
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| Melifluonze wrote: | Ok, so I just ordered an FPGA based HDMI board. I'm going to try to implement the gamma/color adjustments that Nash is wishing for to see if we can get rid of the vertical lines in the blend zone. Life gets in the way though, so it may take a long time!!!
Also, I'm extremely concerned about geometry and linearity, as Nash is... I think this is the biggest problem. If you don't have all areas of the blend zone right on top of one another, there will be differences. This means that for blending to actually work, you have to have the projectors exactly lined up mechanically, electrically, and in any other way, and the images need to stay locked where they are. Any drift for any reason of ANY parameter or location of the image relative to the other = blend zone shows up!
That being said... if you could butt the projector images right next to each other and hold that spacing, then THAT would possibly be the best "blend". You then use the color/gamma corrector to equalize the second projector to the first... If you can't keep the images within one pixel of each other, then blending will fail no matter what you do... By fail, I mean you'll see the blend zone!
It hurts, but I'm starting to think that blending without a blend zone is not possible. There will always be a visible blend zone...
- M |
What your saying is true but on the other hand you shouldn't be experiencing much drift. This is why taking the time to do a extremely thorough set up is absolutely crucial for a blend. You might have to touch up convergence once in a while but not frequently.
IMO, for a blend you need 2 ultra chassis and 2 sets of HFQ900 lenses. Those lenses have the best corner/side focus and since that is the center of the overall image it's pretty important. Nash is not terribly far from having an optimal residential blend. I say residential because industrial blends are usually driven by custom workstations which provide enough control over blend zone parameters to achieve the desired result. At least this is what I have heard from MP and other professionals who have set up or worked on such displays. I told Nash he needs to find one of those units on surplus..lol
If a company like Lumagen would take the time, they could produce the necessary solution. However, there's really no market for this any longer so it requires a talented hobbyist to save the day. My advice is to keep it REALLY simple; focus on the really low end and high end of the curve. The zone really rears it's ugly head above 80IRE.
So stop farting around with those CLD-97's and get to work on this 
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Melifluonze
Joined: 25 Nov 2013
Posts: 262
Location: Upstate NY
TV/Projector: 9500LC Ultra
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| Link Posted: Wed Oct 22, 2014 8:52 pm Post subject: |
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ROFL, CLD-97... Yeah, I was picking one of those up when we met, huh...
I'll be posting about the gamma corrector in a bit.
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Dual Marquee 9500LC Ultras, Dual JVC RS600
Focal Aria 5 custom speakers, HT Tuba
We STILL don't need no stinkin' 7.1!
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Nashou66
Joined: 12 Jan 2007
Posts: 16171
Location: West Seneca NY
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| Link Posted: Wed Oct 22, 2014 10:23 pm Post subject: |
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I have been thinking about the blend zone. I did some more work with Zone Contrast and
got it to look really good!!!! I admit the focus in the blend zone is not dead on. That will also help.
But What I think the issue is the way that Tv one does the Gamma in the blend zone. It is made for a
flat Gamma curve. That is 2.2, 2.35 2.22 or what ever you choose. And CRT's gamma
at the edge of the screen can almost never be flat in the three locations within the blend
zone, top, center and bottom . Because of the drop off in brightness that the zone contrast
can not fix perfectly. So the gamma curve there will never be flat, it will always need more
brightness in the lower IRE's and the upper IRE's are overly bright due to the added contrast
from using Zone contrast Modulation There is a new Gamma curve called BT 1886 I believe .
This is a sloping gamma curve that starts off with a lower gamma on the low end and then
flattens out the rises at the high end. This almost mirrors the same response in the blend zone
when using a CRT, digital projectors can be flat all the way across at the edges of the screen
as in the center, not CRT.
But I watched some stuff last night and messed with adjusting the TV-Ones gamma and you can
eliminate the blend zone down low but on high IRE's it shows up, then you can adjust it to work
the other way, no blend zone at higher IRE's but its seen on darker IRE's. So the sloping gamma
of BT 1886 might work even though it is not one of the choices in the tv one.
Both of these explain that gamma. Spectral's is what I am going by more.
http://www.spectracal.com/Documents/BT.1886.pdf
http://www.chromapure.com/colorscience-gamma.asp
As you see in the graph above provided by Tom Huffman of Chromapure
BT 1886 and sRGB gamma curves would help in the blend zone since the low end would
be a little brighter, helping remove the dark band seen in the blend zone, and on the
upper end the higher gamma would darken or tame the upper IRE's so they are not brighter
in the blend zone and seen.
I have to have a few full days do re do the calibration of each PJ to that standard.
Athanasios
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