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Reds aren't right...

Discussion in 'Projectors, Screens & Video Processors' started by BenC, Nov 4, 2004.

  1. BenC

    BenC
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    I've had my Seleco SVP-400 for a couple of years now, and have recently noticed that reds sometimes look wrong. It's noramlly on skin tones that I notice it. Face have a strange green/red tint to them.

    Any ideas?

    I've taken photos so you can see what I mean:

    All from Shrek 2 PAL DVD:
    Shrek01.jpg: Strange green/red strip down nose
    Shrek02.jpg: Pink dress and Queen's face have weird green/red bits
    Shrek03.jpg: Weird skin tones
    Shrek04.jpg: No weird artefacts
    Shrek05.jpg: No weird artefacts
    Shrek06.jpg: No weird artefacts
    Shrek07.jpg: No weird artefacts
    Shrek08.jpg: No weird artefacts
    Shrek09.jpg: No weird artefacts
    TestPattern.JPG: Test grid

    Settings:
    Source: Philips DVD-963SA using component connections.
    Note: Progressive scan is turn off on the DVD player.
    Line doubler in projector is doing all the work.
    Input: YCrCb
    Contract: 69
    Brightness: 30
    Colour: 65
    Hue: 49
    PK: 25
    Y/C Delay: 16
    White Balance: 6500K
    Gamma: 55 (It's an all white room so needs this to get detail in dark areas)
    Adaptive black: On

    Any
     
  2. JMPremier

    JMPremier
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    Looking at your test grid the convergence is out, this can be seen most in the far left centre and the top right corner.

    John
     
  3. Chris Frost

    Chris Frost
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    The convergence definately needs a tweek. The red/blue misalignment will emphasise any colour tracking problems and Y/C delay errors.

    Other pointers to improve performance would be an iScan line doubler or some other external scaler. The Seleco internal line doubler softens the image and can introduce a subtle warm colour cast to the picture. A s/h iScan can be had for around £150. Picture definition would take a big leap forward. It would be easy to install.

    Next, have a look at a grey scale ramp from AVIA or Video Essentials and check out whats happening to the colour balance as the brightness steps up from black to white. If you see a predominance of any particular colour in the grey bars then you'll know if the colour tracking needs adjustment.

    The proper cure for this is an ISF calibration of the projector. Gordon Fraser of Convergent AV is your man for this sort of work. A quick search of this forum or the Advertisers section will point you to his web site and services.

    Regards
     
  4. BenC

    BenC
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    Thanks for your input gents. I seem to be forever tweaking the convergence (with a warmed up projector) until it's as close to perfect as I can get it. Then I save it, and return a few days later and it's drifted!

    I have been considering an iScan, which prompts another question:

    When I installed the proj a couple of years ago I installed three coax cables for RGB, and an S-Video cable. An iScan will need RGB + HV, so I need to install two additional cables for H + V. This is a big job (involving projector removal, access to ceiling cavity etc...) so I was thinking maybe I could snip off the S-Video connectors and then add suitable connectors for the H and V signals.

    Would this work? Is it a compromise? Should I just bite the bullet and pull my living room to pieces to install new H and V cables?
     
  5. Chris Frost

    Chris Frost
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    You should tweak maybe a couple of times a year, not a couple of times a week!! You either have a herd of elephants stampeding in the room above or the convergence is being worked very hard to compensate for something more fundamental that isn't adjusted correctly.

    Have you found some of the convergence settings at or near their max/min values?

    Go back to basics. Do the physical lens alignment, then the deflection followed by convergence. Most convergence settings should end up in the 30-70 range.

    That's not a good idea; and besides, there's a much simpler solution.

    If you are using the Seleco ceiling bracket then there is space above the projector for an iScan.

    iScan has 2 x component, 2 x S-video and 2 x composite inputs. Output is 15pin D type - signal switchable between RGBHV and ProgComponent.

    Put the iScan on top of the projector. Feed Component in from the 963SA. Connect iScan to 400 using a short 15pin D type to 5 x BNC. No rewiring required, good quality signals, and you still keep the S-Video for hooking up Sky+ or standard Sky with and RGB to S converter. Simple. :)

    The bonus is that the iScan has priority switching built in. You don't need to worry about switching sources on the iScan. If the DVD player is on then that will take priority. Switch the DVD off and the iScan looks for the next available signal which would be S-video in our example. Even simpler!! :thumbsup:


    Regards
     
  6. BenC

    BenC
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    Chris - What can I say? Genius. Brilliant idea. I wish I'd thought of that a couple of years ago.... I'll put a wanted ad in the classifieds right now.

    With regards to the convergence, I've spent a few evenings this week tweaking it, but in all honesty I'd not touched it for four months prior to that, so I don't think it is actually drifting, I just think my convergence skills still aren't great.

    I've just been through all the settings in DEF and CONV and most are between 40 and 60, with just a few creeping to 30/70. I think I just need to spend a bit more time staring at those wonderful grids.... I'm going to get the Avia DVD too.

    Thanks again for the suggestion.

    Ben.
     

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