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Discussion Starter · #1 ·
I have an HTPC driving a Sanyo XP21N LCD projector and want to do some color calibration. I have the Avia disk but all I find are 'saturation' and 'hue' whereas the projector choices (when in computer mode) are 'red', 'green' and 'blue' (makes sense, RGB and all). Can I use the Avia disk to calibrate such a monitor? If so, how? If not, what else would I need (Video Essentials?)


Help appreciated!!!


SFC
 

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Yeah I could use some help on this one too.


Cameron


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-- Well I have really blown my budget now. --
 

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My goodness it's been hot in Walnut Creek for the last couple of days- 104F/40C- too hot for projectors and Mac Cubes...



Well, there is calibration, and then there is "Calibration". This is how I "Calibrate":

Saturation and Hue are factors of the video stream. That is, the stream feeding the RGB converter in the projector.

Typically, they are adjusted when feeding a composite, Svideo, or component input to the projector. This can come either from a deck, or from a HTPC video card with video out.

Not knowing the details of your HTPC, I can suggest only a few general guidelines.

1) _Don't_ use video out from a card. Use the "VGA" out. This has the separated RGB signals on it, and bypasses the projector's internal converter.

2) Depending on what software you use, you need to calibrate your HTPC first. This means using a standard RGB monitor. Software varies on the PC side; I use ColorSync with a Mac.

With Colorsync, you create and save a profile for any device hooked up- scanner, camera, color printer, monitor. etc. The idea is that you match the original source material to the final display device, _irregardless_ of all the circuitry in between.

In your case, you would use the AVIA DVD as source, and your monitor as display. Why not just go right to the projector? Projector characteristics vary widely, far more so than monitors. You want to make sure that all the hardware and software in your HTPC is up to snuff first.

ColorSync will get the RGB balance, temperature, and gamma correct. Then check out a couple of DVDs on the monitor. Look especially for "blooming" and color balance between light and dark scenes. What you are doing now is calibrating your eyeballs- getting a feel for what looks right and wrong, and why, without putting hours on the projector bulb.

3) Hook up the projector- many have a pass-through feature that allows you to hook the monitor up as well. If your projector does:

4) Run ColorSync again, just looking at the monitor- it _should_ be the same. If it isn't, you have a cabling or termination problem, and that should be fixed first.

5) Turn on the projector, let it warm up for a while- at least ten minutes. Set all projector values to default, and run a standard DVD, one that you are familiar with. Try to eyeball the projector and monitor together- look for differences. You will want to set the brightness and contrast first- ignore color issues for now- using the projector's controls. You will probably not be able to duplicate the contrast range of your monitor for a number of reasons elaborated on to death in other parts in this forum.

6) Once you have achieved a reasonable compromise, start checking the color balance. _The phosphors used in monitors and the dyes used in projectors have different spectral characteristics, and you will never get a perfect match!!!_


But you can get close.

If you find that the RGB balance of the projector has to go significantly (+/- 10%) off from the defaults, it is time to create a new ColorSync, for the projector itself. Restore the RGB projector defaults, and turn off the monitor- it's a distraction at this point. If it takes less than 10%, you're done. (Mostly...)

7) Run ColorSync on the projector. The dynamic range of most modern video cards is greater than that of the projector, so if you find that you have to push the Reds a little, which is typical of many LCD projectors, and pull the greens, do it in the HTPC.

8) Save the profile, and remember to change it when switching back to the monitor.


Whew!! Are we finished yet. No. This was just the HTPC DVD player. If you are feeding video into the HTPC, say DV over FireWire, you may need to create a _new_ profile for each option, using the same routine- monitor first, then projector, maintaining consistancy. Once you get the hang of it, it goes pretty quickly, which is a good thing, because:


9) Repeat every 20-50 hours of projector time- bulb characteristics change greatly over time, and a good clue that the bulb is about to go is the _need_ for frequent recalibration.


10) Remember our friends Huey and Saturationy? You only adjust those with _video_ feeds from a deck, LD, converter box, camcorder, etc. Since most projectors can't save multiple settings, (Maybe modern ones can... my Epson is a couple of years old...), write down or memorize the settings for each one.


11) And then there is your TV set, hooked up to all the same equipment, and used for news, etc. Make it look as much like the projector as possible, even if it does leave Dan Rather looking a little Green around the Gills. You'll get used to it quickly, and the shock of going back to the projector won't be so great.


apg

 

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Discussion Starter · #4 ·
apg


Yes, it has been (and remains) quite hot in Walnut Creek! Berkeley (where I work) is much cooler!!!


Many thanks for the post, which I am still digesting. I am using a PC (not a Mac), so any suggestions on something like ColorSync for this plateform (or would ColorSync work)? Also, I am using the VGA out directly to my projector. Also , my 'primary' display is a 15' digital LCD (for what it's worth).


Lastly, I can use the Avia disk to adjust contrast and brightness, but I struggle is how to best adjust red/green/blue. Your suggestion to adjust with the PC makes sense, but I am still unclear on exactly how to best do that adjustment. Is if purely visual comparison to my primary monitor (isn't there something more quantitative)?


Thanks in advance,


SFC
 

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Powerstrip is a software package that many people use on the PC. Search for it on the web - there is a free demo version that you can download.


It will do the best it can with your PC graphics card - and you may be amazed how much your graphics card can do. You can adjust RGB, colour temperature, gamma, frame rate and all sorts of other things too.


The only thing is, on some PC cards, the Powerstrip adjustments only apply to the main display and not the "video overlay". That means that you can adjust the colour settings for everything except DVD!!!!! The solution is to get a new video card for your PC, which should be fairly inexpensive.


Personally I have an ATI Rage 128, which does not allow the video overlay to be adjusted. Maybe other users can post card which do allow this.
 
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