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Discussion Starter · #1 ·
I have an HTPC connected to a plasma display and I would like to be able to correct for a problem with the display having a non-linear gray scale tracking curve (ideal display would have an smooth 2.5 gamma) by using some type of display utility that would allow me to create and apply an arbitrary gamma "correction" curve. I have looked at powerstrip and the ATI control panel, but neither seems to have the required gamma control flexibility. Ultimately the best way to fix this is to have the display calibrated but it would be interesting to try this out first. Any suggestions would be appreciated.
 

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I can't see how you can do this without instrumentation. Unless you have a colorimeter around?


Something like an Eye One Pro (cheapest is Eye One Design at around $800 US) or a much cheaper SpyderTV ( $300?) could be used. Or maybe a Spyder2Pro.


The Eye One Design and the Spyder2Pro should create ICC profiles - but I'm not to sure if the ICC profiles are only provided by applications that support it (ie. only in Photoshop), or if the ICC profile actually changes the LUT tables on the videocard.
 

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Discussion Starter · #3 ·
I believe I could kind of eyeball it by putting up a smooth gray scale ramp and hopefully use the utility push up or down points along the gamma correction curve until it appear smooth (or at least smoother).
 

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Discussion Starter · #5 ·
Quote:
Originally Posted by dlarsen
You can create a custom look-up-table in PS to create most any function you'd like. Also search on ICM profiles.

http://www.avsforum.com/avs-vb/showt...&post6020875


Dave
I didn't realize you could do that with powerstrip. It looks like it offers very precise control but being text based is very complicated. Is there a utility that uses a graphical interface to createing a gamma correction curve by moving points up or down along the curve either by a series of sliders or grabing the curve with a mouse?
 

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"Is there a utility that uses a graphical interface to createing a gamma correction curve by moving points up or down along the curve either by a series of sliders or grabing the curve with a mouse?"


the nVidia video drivers have this feature....


:cool:
 

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I remember somebody working on a util that did this a few years back. It was a sort of wizard, much like the software that comes with some computer monitors for getting your color set up correctly. The only thing that made it less than useful for me was that it only corrected the gamma curve of your windows desktop display... not the overlay, which I was using then for DVDs.


Wish I could remember where I found it, who made it etc.


Maybe search in the archives?


Gerald
 

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Quote:
Originally Posted by maxleung
I can't see how you can do this without instrumentation. Unless you have a colorimeter around?


Something like an Eye One Pro (cheapest is Eye One Design at around $800 US) or a much cheaper SpyderTV ( $300?) could be used. Or maybe a Spyder2Pro.


The Eye One Design and the Spyder2Pro should create ICC profiles - but I'm not to sure if the ICC profiles are only provided by applications that support it (ie. only in Photoshop), or if the ICC profile actually changes the LUT tables on the videocard.
The SpyderTV would be the best way to go at the low end. It will get you a basic calibration in ~30min, and then you can fine tune it using xyY data the rest of the way using the "/support" switch.
 

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Discussion Starter · #9 ·
Quote:
Originally Posted by Ursa
The SpyderTV would be the best way to go at the low end. It will get you a basic calibration in ~30min, and then you can fine tune it using xyY data the rest of the way using the "/support" switch.
I thought about buying the SpyderTV but it is my impression that the software that came with it is only for basic contrast, brightness, color and tint adjustments, which I can manually do with my AVIA CD, and that you need to upgrade to there Pro software for $100 in order to do more complex gray scale tracking adjustments. Also am I correct in assuming that the xyY is only useful for creating an ICM profile for when a computer is used as a source? I was hoping that I could use the SpyderTV to adjust gray scale (gamma) tracking through my plasma's service menu to permanently corrected for multiple inputs and resolutions. What is your thoughts?
 

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Quote:
Originally Posted by mhfnet
I thought about buying the SpyderTV but it is my impression that the software that came with it is only for basic contrast, brightness, color and tint adjustments, which I can manually do with my AVIA CD, and that you need to upgrade to there Pro software for $100 in order to do more complex gray scale tracking adjustments. Also am I correct in assuming that the xyY is only useful for creating an ICM profile for when a computer is used as a source? I was hoping that I could use the SpyderTV to adjust gray scale (gamma) tracking through my plasma's service menu to permanently corrected for multiple inputs and resolutions. What is your thoughts?
The SpyderTV, as delivered, will only do basic controls as you indicate. However, setting the support switch gives you xyY data. You can use that data to do a simple grayscale calibration (say, to a defined white point like D65), or a complete calibration (using service menu controls or otherwise) with a bit of math. Check out www.poynton.com and www.brucelindbloom.com for reference if you want to build your own model. If you would like a pre-canned solution, then there are a few posted here on the forum (mostly in the >$3500 projector forum), or you can get a commercial one (umr's, mine). See my SpyderTV review if you want to see what you can do with xyY data and some Excel love...


ICC and ICM profiles are, loosely, adjustments to your computers outputs to make your display accurate. OptiCAL and the PRO package include a "PreCal" routine that is a less automated version of what the SpyderTV software does. The TV software does not do any profiling; all of its adjustments are put into the display itself.


HTH!


Later,

Bill
 

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Discussion Starter · #11 ·
Bill,


Would your spreadsheet and a SpyderTV give me information needed to make gray scale tracking adjustments on my plasma and if so would you be willing to share a copy of the spreadsheet?


Thanks, Mike
 

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mhfnet: Why wouldn't you just have the set calibrated and then it is your "reference". Working from the display back to the equipment gives a great result in practice. I had my display CIE calibrated and then only very minor adjustments applied within the graphics card software if necessary (mine is Nv 6600GT at the moment).
 

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Quote:
Originally Posted by mhfnet
Bill,


Would your spreadsheet and a SpyderTV give me information needed to make gray scale tracking adjustments on my plasma and if so would you be willing to share a copy of the spreadsheet?


Thanks, Mike
Mike,

Yes, my model will give you the calculations and charts pre-canned for HD, SD and PAL. you can see my SpyderTV review for some of the charts I created. PM me if you are interested (please note the wording I used to describe it in post #10, above).


Later,

Bill
 
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