Dismiss Notice
Attention AVForums app / Tapatalk users
Sadly GDPR means that, from 25th, we can no longer offer access to AVForums via the branded app or Tapatalk.
Click here for more information.

Edge Blending Contrast Modulation Twin Projection

Discussion in 'Projectors, Screens & Video Processors' started by Mad Mr H, Jun 10, 2005.

  1. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    (I have deleted some of my "general chat" posts in this thread to keep it more to the point and shorter - I am now on track with this and things are starting to move forward - watch this space)

    This is a combination of my posts so far to try and keep blending posts together (from elsewhere).PLEASE voice any opinions you have.

    .....and so it begins.....

    Blending options software, firmware & external equipment I have looked into

    Nvidia Quadro FX cards, others did not get good results from these cards BUT they were using the FX1000 , I have on test the FX4000 AGP card, support for edge blending on the FX1000 has been dropped by Nvidia, the FX4000 is still supported. Nvidia now have pci express 4400 and 4500 versions. 4000 is still the top AGP card

    Watchout - PC based software - approx cost £4,500 for the software and you need 3 pc's

    Analogue WAY - £16,750 - hardware based

    Panaram - hardware based - £25,000 - Hardware based

    Matrox PJ range of cards - offer 3 & 4 head display with OVERLAY only. $2000 or $3000 - PCI card based - NOT ON GENERAL SALE but current models

    DScalar - currently being looked at

    Baro SEMU - I have 2 boards not sure if SEMU or SEMU lite - can only tell when in projector will update as I find out

    Barco polaris - software for use with projection within domes etc

    Powerstrip - still to investigate this

    Items I have so far

    Nvidia Quadro FX4000 card Grapics card in HTPC

    2 BG1208s/E with convergance on green boards (These wont fit the 801s ). Six new P16 tubes. Contrast modulation board WITH soft edge optional board

    I will try and post pics as this moves forward

    My reasons for trying this are as follows​

    Use of more vertical tube size so higher resolution and brightness- My Main Reason (see below*)
    Slight increase in brightness PJ nearer screen - not a main reason
    Better convergance stability PJ nearer screen - not a main reason

    * I have a fixed 16:9 screen, widescreen from one PJ uses 75% of vertical tube height - hence the masks you see on loads of tubes
    As I calculate 2 PJ with a 25% overlay should use 98.4375% of the vertical tube height - and greatly increase the resolution to a total picture of 2100x1600 and give a 25% increase in brightness per projector, which will mean a % increase in brightness overall not sure how that bit works !

    I know there are people out there who dont think this will use any more tube area - I could be wrong - but to date no one has convinced me of that. The combined tube area becomes almost (within 2% inc. overlay) a native 16:9
    ( :D Boy I is gonna feel silly if I got that wrong :D )

    Maybe I will fail :( but along the way I will have tried something new, had a bit of fun, and will accept the "told you so's" of course if I succeed "A large shout of were not worthy" :) will be heard from the non believers.

    Currently the odds are 15% in the blenders favour and 85% against
    (Changed odds following my 12 projector line up for 360 deg projection)

    Other threads

    http://www.avforums.com/forums/showthread.php?t=232978 - info about rgb bgr tube reverse in stacked systems

    My own notes in case anyone wants to follow my progress


    Original idea started from conversation with Roland, this is a test system to see if it is worth the investment of 2 x Barco 120* series projectors (which I have now bought as the project is taking a long time and the oportunity came by)

    Nvidia Quadro FX4000 - Installed in my HTPC running v7.x.x.x latest drivers
    Picture quality noticed as better than prvious card (ATI 9600 AGP I think)
    NOTE: Change of graphic card or any signal replated parts and convergance check - noticed very minor convergance differance between cards - this initally made picture look a bit out of focus or grainy, now rectified.
    Colours are however much more vibrant

    tested new quadro fx4000 card - my view is that it gives better detail definition and the tonal colour output is better than my original card.
     
  2. javers

    javers
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hi, this seems a very interesting project. I'd be very happy to see a working blend system, the ht crt world needs one! I'll be watching this thread closely. If its any use I've got the remains of a BD801 (non s), has a mint blue and red tube, but green tube is cracked :mad: smps needs fixing, oh and the vert def / sync board is also knackered. Apart from that shes a good as new!

    Jon
     
  3. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    Andy what have you started!!!!!
    It was along the lines of "that would make an interesting project". I never expected you to go and do it.

    Ironically my cinema would be perfect for this because I have a large beam running down the centre.

    All I can say at this stage is that you have long road to go here. Your placement of the projector will be key. Aim to get at least 20% overlap for it to work well. Less than 10% and It will be difficult to allign. If your screen has any form of gain on it colourimetry will be a dog. If you have to take the tubes out some people find it better to have one set reversed. RGBBGR

    I knew the states have tried this from a PC and failed but that was some time ago I thought I read someone got it to work.

    One route you have not explored is to use a video splitter from DVD or what ever source into identical video scallers. Most of the modern ones allow you to over scan and phase the image over to one side or other.

    You have clearly been out shoping since we spoke and seem to have become the resting place for a lot of kit.
    I have a few 800 and 801s projectors one of which would be good for spares the others have good tubes. I haven't got round to photographing them yet.

    The Barco Semu is just thier name for softedge on the later machines (Soft Edge Modulation Unit)

    Becarefull on the resoltion you choose because the higher you go the less the phosphor is excited and hence the brightness will fall off. 1200x1600 on an 801 will make an intersting noise (even more interesting later)

    I know I should not say this in the CRT forum. but LCD and DLP projectors can do this really easily beacuse most of them have the zoom and phase built into their software. All you then do is cover part of the lens with a piece of card at the right distance and hey presto soft edge. Great use for an old 4x3 pannel projector
     
  4. helipilot

    helipilot
    Active Member

    Joined:
    Sep 20, 2001
    Messages:
    319
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    18
    Location:
    Hamilton
    Ratings:
    +19
    This is an appealing idea as my screen size is limited due to the length of my room. Setting up two projectors using more vertical phosphor would allow me to get a bigger image. I will watch this thread with interest to see how you overcome the problems.

    My initial thoughts are that you will end up with a lot more than 25% overlap. I have attached a small image to show why. The top image shows a conventional 4:3 tube with anamorphic squeeze to 16:9. The lower image shows two 4:3 tubes side by side to achieve 16:9 using full height of phosphor. Also with such a large overlap how will you avoid having a bright centre and dull edges.

    best of luck


    Alan
     

    Attached Files:

  5. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    This is the point of soft edge blending. The brightness of one projector is reduced to match the output of the other.So in theory when they overlap the brightness will match the rest of the screen.
     
  6. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    Scallers only experiment will tell, but they need to be the same like identical

    Running any projector too hard will cause heat build up and stresses. an 801 at 1200x1600 running softedge too will be a lot for the poor old power supply to cope with.

    The order of the tubes has me wondering now but I'm sure I'm right. Whilst you will always get colour shift from side to side depending on which side of the screen you sit. The effect will be reduced in the centre which will be the most difficult to get right.Thge idea is that you don't want one colour coming in at a greater angle than it has to. so by moving the colours around the effect in the centre and the far edges should be improved.

    1208/2 will be a good machine to play with
     
  7. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    sofe edge blending and contrast modulation are to remove the bright overlap area and blend into one picture.

    my thoughts on the overlap area are as follows.... :lesson:

    tube 4:3 - use full height of all tubes

    side by side would give 8:3 or 16:6 - obviously too wide (aiming for 16:9)
    16:6 is too short OR too wide, cant go any taller as full tube in use so must reduce width - this leads to an overlap.

    16:9 is same ratio as 5.3:3
    two projectors create 8:3 so you must reduce the 8 to 5.3 to get a 16:9 (5.3:3) format
    from 8 down to 5.3 is a 33.75% reduction so the overlay area will be 33.75%

    (Hope thats ok to follow!)

    This assums 4:3 use of tubes, which will not be 100% correct due to keystone etc BUT as a starting point shows maximum overlay could be 33.75% so to aim at 25-30% seems possible.
     
  8. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    I have given this some thought......

    think of a vertical thin line anywhere from left to right of screen, at any point using the reversed tubes the image would have an even edge both left and right as projection arriving from 2 different sides, often you will see red or blue on the different sides of faces etc (not just bad convergnce!)

    would you have the blues together or the reds? I guess the blues. the closer they are together the less this even dispersion will show, as you dont see blue so well I guess that would be the ones least important and so together...

    or am I way off mark?
     
  9. Roland @ B4

    Roland @ B4
    Active Member

    Joined:
    Apr 11, 2001
    Messages:
    2,238
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    51
    Location:
    Reading.
    Ratings:
    +32
    I think blues too

    Andy if your installation allows you to to be able to adjust the distance between the projectors from the centre line it would be worth having it. The electronics on these 801 projectors will be about 10 years old now and a bit of manual adjustment could be usefull.
     
  10. javers

    javers
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Hehe, can't tempt you with a second BG1208/2 can I?
     
  11. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    :D found these so thought others might like to see :D
     

    Attached Files:

  12. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    For those thinking of multi projector images this is for you

    (In this case the use of 12 DLP projectors - forgive me but 12 pj's 5m in the air was hard enough with out the weight of their big brothers!)

    Pictures are as follows

    1. Bare rig, comes in 12 sections, shown bolted together ready for outer skin
    2. Completed rig on floor ready to "fly"
    3. rig "flown" to populate
    4. rig populated
    5. First quick line up - 6 hours and rough screen widths set
    6 & 7. projection image without lower curved line - another 5 hours on...

    rig not completed but you get the idea - maybe some one has a round room ???
     

    Attached Files:

  13. Tim in Phoenix

    Tim in Phoenix
    Active Member

    Joined:
    Dec 2, 2005
    Messages:
    82
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Location:
    Phoenix Arizona
    Ratings:
    +8
    Alan

    I do not anticipate a cheap way of doing edge-blend that is stable and user-friendly; we tested here two years ago with $34K of Folsom gear, nice image but awkward to operate. We are testing another new system here, before Christmas I hope, and this will at least be user friendly; Stay Tuned!
     
  14. Tim in Phoenix

    Tim in Phoenix
    Active Member

    Joined:
    Dec 2, 2005
    Messages:
    82
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Location:
    Phoenix Arizona
    Ratings:
    +8
    Guys!

    The pic upload thing is fighting me here, trying again:
     
  15. Vince M

    Vince M
    Standard Member

    Joined:
    Nov 2, 2004
    Messages:
    479
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    19
    Location:
    Lagoa
    Ratings:
    +0
    Yes this could work,better would be two outputs from a scaler outputting the same signal..or splitting out of the scaler..one way may be to come out of the scaler via dvi into a dvi splitter and have a dvi card in each crt,I know this could be possible for Marquees..dont know if theres a dvi card for Barcos?
     
  16. Tim in Phoenix

    Tim in Phoenix
    Active Member

    Joined:
    Dec 2, 2005
    Messages:
    82
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Location:
    Phoenix Arizona
    Ratings:
    +8
    Guys!

    The requirement for HDTV with 1920 horizontal pixels is 2/3rds (left segment) and 2/3rds (right segment) with 640 pixels of overlap, which requires contrast modulation for a seamless overlap.

    The attached picture shows white field inputted from a generator and we have blanked the top edge of the left projector and the bottom edge of the right projector to demonstrate the rolloff needed.

    A dedicated 2.35 system could also be had; that would entail a 12% overlap; we have not tested that. This test was with Folsom gear from two years ago.
     

    Attached Files:

  17. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    What PJ's did you use here?

    It may also just be the pictue but I can see the right hand edge of the left hand projection.

    Colour balance of the 2 pj's also plays a part does it not?

    As I undrstand the 2 pj's need to be a close match, identical is good....

    That is what I am currently trying to do with mine...
     
  18. Tim in Phoenix

    Tim in Phoenix
    Active Member

    Joined:
    Dec 2, 2005
    Messages:
    82
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Location:
    Phoenix Arizona
    Ratings:
    +8
    Guys!

    Identical projectors are preferred, we used a pair of Marquee 9500LCs here; the visible edge is due to not having two machines with all new tubes installed; the left unit had some green phosphor wear. That was not visible on motion video scenes except full white backgrounds. Ten-bit contrast modulation is preferred to best hide the overlap. There is nothing quite like near 500 ANSI lumens with CRT contrast and punch! Lower gain screen fabrics are best; our earlier testing was on a 1.1 fabric of 111" width, screen widths to 120" should be very satisfactory, maybe larger in a black room; we hope to test with some DLP units soon and if the black levels are decent then fifteen or twenty foot widths could be supported.
     

    Attached Files:

  19. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    OK, My pair have NEW (not rebuilt) P16 tubes. ALL 6 are new.

    I also have a colorimeter (thorma TMF2)

    So looks like im going the right way.....

    I also have 2 matched 1208s/E and a few spare!

    I was thinking one 9" but have been talked into the 2x8" idea.

    A blend was always my dream and is still my aim.

    I only know of Art's stack (g90's) and no one else. (Home cinema)

    I dont know of any blend owners - In a house I mean......

    ALL of your pictures are welcome here, very welcome.
     
  20. Tim in Phoenix

    Tim in Phoenix
    Active Member

    Joined:
    Dec 2, 2005
    Messages:
    82
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Location:
    Phoenix Arizona
    Ratings:
    +8
    Guys!

    Side stacking is doable but there are issues; side stacks require pushing geometry settings to the limit, you have to throw two trapezoids to be squared at the screen; short raster at one side and stretched at the other, and major use of H Linearity correction also. Edge blending lets you shoot straight ahead with 2/3rds the throw distance, so smaller rooms are not ruled out. We have more testing with a new processor slated for mid-December so we will update this thread soon.
     
  21. crispybig

    crispybig
    Active Member

    Joined:
    Sep 28, 2004
    Messages:
    293
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    21
    Ratings:
    +6
    The above from another thread

    I can see why this is of benefit with a conventional stack, but I'm not so sure with your blended stack (at least I understand that's what you're aiming for :D ). Instinct tells me that you should go RGB RGB for a blended stack. I've been manually "ray tracing" on paper here, but just confusing myself :mad: .

    With a 100% overlapping stack (like Art's) there is cancellation, but that's not as obviously the case with a blend. I keep thinking that a blend doesn't have to be two PJs - it could be three or more. I know - this is hypothetical thinking! :) With a three-way blend you couldn't have RGB BGR cancellation, as there is an extra RGB to contend with. It seems to me that when blending an infinite number of PJs (VERY hypothetical!) you would have to go RGB RGB RGB RGB......... etc.

    So if that's the "rule" with multiple PJs why should it not also be the case with just two?

    You are breaking new ground here :thumbsup:. I think RGB BGR versus RGB RGB is "fine tuning" that can wait. If I were doing it (which I would be if I had the room) I would concentrate on getting the basic blend right, only then would I consider the pros and cons of the tube phasing.

    Hang on in there - I can't wait to see the results! :)
     
  22. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    ALL I can say is last night I watched a film drank a nice bottle of Champagne and then decided to mess with my graphics card....

    NOW all I can say is the FX4000 has without question got edge blending built into it......

    AND that only using ONE PJ as a test I can get a single edge blend - only one side not all 4 at the same time.

    AND I dont understand the settings BUT they are all variable....

    Tim - this could rock your world...........

    It looks like I can vary the "blend zone" in pixels - but in pre set amounts like groups of 32

    I can adjust the "fall off" values

    And I cant remember the 3rd setting!

    I will take some screen shots......

    Oh......and I have a couple of possible surprises im working on....would love to tell you all BUT they are not here yet.......

    No one is getting a crimbo pessie from me this year! Im spending way too much in myself Humbug.
     
  23. Tim in Phoenix

    Tim in Phoenix
    Active Member

    Joined:
    Dec 2, 2005
    Messages:
    82
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    8
    Location:
    Phoenix Arizona
    Ratings:
    +8
    Guys!

    Screen gains in the range of 1.0 or 1.1 are preferred, so hot spotting and color shift have not been factors in our earlier tests. We routinely did three-projector blend systems in Detroit for the car companies when I was there six years ago. No video but high resolution computer stuff And stereoscopic with goggles. Full size cars leaping off the screen at you, very cool.
     
  24. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    I can feel the force is getting stonger.....

    there is a blender working in the world (no James not a kenwood)

    yes, yes, I feel soon the world will see a new dawn.....

    and just for James it says Electrohome.....
     
  25. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    A quick Sneak preview........

    [​IMG]
    [​IMG]
    [​IMG]

    and just for James...

    [​IMG]
     
  26. nin

    nin
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0

    Why is that? Do you want much more brighness or?




    I have a link in my computer somewhere about a guy that have two Runco DTV-1200 (Barco Cine 9) as a stack, calibrated by Ken Whitcomb. THAT would I like to see :D
     
  27. Barcoing Mad

    Barcoing Mad
    Active Member

    Joined:
    Oct 14, 2004
    Messages:
    1,453
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    64
    Location:
    Norfolk
    Ratings:
    +216
    Hang on, Mad. Where the hell did those Marquees come from? I've just had to rush back to the cinema room to check that mine are still there.
     
  28. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    Hi nin,

    Brightness is really only gained if you stack. And an increase in CR.

    Blending gives you additional resolution, and bragging rights.


    If you can find the link to the Runco-DTV1200 that would be nice...I collect pictures related to this topic and have posted many here and other forums.



    My original idea is currently under question....

    I decided to go with 2x8" and have almost finished the 2 I was going to use......Then I appear to have bought a 9".....So maybe I hang them all :devil:
     
  29. Mad Mr H

    Mad Mr H
    Well-known Member

    Joined:
    Jun 10, 2005
    Messages:
    4,460
    Products Owned:
    0
    Products Wanted:
    0
    Trophy Points:
    106
    Location:
    London
    Ratings:
    +280
    I have "borrowed" the pictures from a top secret trial site!;)

    Wednesday should see some more news,:smashin:

    And for those that think I have turned my back on BARCO, not a chance the Quee's are not mine and the TEST ZONE is a very long way from here in a USA based location....

    I was just sent the pics as they know my intention to blend.....:D
     
  30. nin

    nin
    Guest

    Products Owned:
    0
    Products Wanted:
    0
    Ratings:
    +0
    Ahh, sorry, thought you would stack :oops:

    I will look at it. The theater was VERY impressive and that guy had no problem with money (this was 3-4 years ago).
     

Share This Page

Loading...
  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice