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Does SMART III perform D65 calibration?

Discussion in 'Projectors, Screens & Video Processors' started by John_N, Mar 17, 2003.

  1. John_N

    John_N
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    Hi

    After all my previous posts on D65 calibration and using SMART and the way that SMART II relies on the projector 'low' setting, I'm now confused even more because I read a post elsewhere on this forum that Smart III uses a more expensive light meter and better quality RGB filters and therefore does not rely on your projectors 'low' output to get the colour temperature right.

    My main objection to SMART II was that it would be no use recalibrating an HS10 projector after adding a CC40R filter because your colour balance is definitely and hopelessly wrong. However, if I could use SMART III to reset my colour balance I would be very pleased!

    So. what's the story? Has anyone used SMART III? Does Smart III attempt to get the colour temperature correct without using the built-in 'low' setting on the projector? How does it do it?

    Any feedback?
    John
     
  2. Gordon @ Convergent AV

    Gordon @ Convergent AV
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    John,

    From reading Steve's pages about SMART 3 the answer has to be NO.

    He says it ESTIMATES the temperature for graphical representation purposes.. There is no mention of D65. I have SMART2 and I have my spectroradiometer. The VPL11 is waiting to be calibrated. Doubt I will have time this week as I have a TAX return to do.....yuck!

    Gordon
     
  3. Russ

    Russ
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  4. Mr.D

    Mr.D
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    As I mentioned in the other thread: SMART is using a technique colloquially reffered to in the trade as "curve ripping".

    You are not calibrating to 6500K you are calibrating to mimic the RGB intensity response curves of a known "properly" calibrated projector of the same model as your own. ( think of getting a copy cut of a master key)

    In principal it works ok :however you need the calibrated referenced aims ( taken from the calibrated refrence machine) to calibrate to and hope your lightmeter has roughly similar characteristics as the one used for the initial reference. At best you'll get close to the accuracy of the referenced machine : you'll certainly not get any higher accuracy beyond complete fluke .

    The only other thing I'd imagine you would need to do is set the white point and black point accurately ( to the same as the referenced machine) before you start tweaking the curves.

    To be honest you could start with the default settings to 9600K and if there was enough intensity response in the projector you could recalibrate back to 6500K aims even though the projector was set to the 9600K setting. Likewise gamma will also be transparent : as long as the referenced machine is accurate in this regard and you can actually tweak the RGB intensities of the projector along the curve. ( light meters tend to go innacurate towards the low end: even the expensive colour analyser ones but if your making 20IRE jumps along the greyscale its probably not an issue). Also if you can't reach the same whitepoint as the reference machine the calibrated curves may introduce banding. ( not sure what smart does with regard to whitepoint dropping over time: advise you to get a new bulb most likely!)

    Some designed response curves incidentally are considered intellectual property.
     
  5. John_N

    John_N
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    Thanks Keith, that's a very clear response. I thought that it had to be doing something similar.


    J
     
  6. Mr.D

    Mr.D
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    You are right in that it would be no use in conjunction with the CC filter ...unless the referenced machine was calibrated with the filter in place initially.
     

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