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Discussion Starter · #1 ·
Well my new CF-6000 has arrived and it is fanastic. I've been working on calibrating my Sharp 10000 and will have a full report once I've had enough time to test various scenarios and digest the results.


But first I'm wondering if any of the calibration expects out there have any suggestions for the best way to dial in the CIE chromaticity.


I have my color system set to SMTPE-C w/ D65 white point. When I first measured the device primaries green and blue were very close and red was too far down and to the right (no surprise there - the reds are noticably hot out of the box).


Then shortly thereafter I took another reading and found that greens were too high and blue was a bit to low and to the left. The first reading I tried was with out of the box settings, and I'm sure I went back to all default settings but the green and blue consistent read as mentioned above.


My problem is that I cannot get the green or blue correct no matter what I try. I was able to correct the red by lowering its lumenance and chroma and raising its hue - in fact red is now perfect.


But no matter what combination I try for green and blue, I can't get their pionts to move in the right direction. I can get them to move in the wrong direction and by significant amounts so I think these CMS (Color Management System) settings are the right ones to tweak - plus it worked with the red.


I have noticed that changes to any colors gain or offset do not affect the CIE. Neither does a chance to another color.


For example, the best I've been able to dial in green is have it come down to the save horizontal level as the green reference point. But its still a good bit to the right. No combination of settings will move it to the left where it needs to go. Likewise blue is a bit up and to the left of its reference point but will not adjust where I need it to go.


I know the Shapr 10K has excellent color control so this must be something I'm not understanding or doing correctly. My lamp has about 50 hours on it.


Any help or tips would be greatly appreciated. Thanks!
 

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I think we we get that book, Video Demystified, we will have the chromacity setting answers. Before that, you might want to give Tom Strade at Immersive a quick call, he owned a Sharp XV-Z10000 for a while and knows how to calibrate it. He essentially sold it to purchase a Yamaha because of several features (not calibration related) the Yamaha has that the Sharp doesn't. The Sharp XV-Z10000 is the calibration tweakers' King.
 

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What spectroradiometer/system are you using to measure, ColorFacts?


I'm a little bit confused - you're trying to adjust your primaries? You should only be able to change the luminousity of the primaries, not their chromaticity coordinates.


Really what you want to be doing is making sure that your whites are D65. There are an infinite set of coordinates for your primaries that can be mixed in the right proportion to make D65 white.


Mike
 

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You cannot change the primaries. If you are getting different readings for them the probe is drifting or something else is wrong. Take dark frames often.
 

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Discussion Starter · #5 ·
Quote:
Originally posted by mflaster
What spectroradiometer/system are you using to measure, ColorFacts?


I'm a little bit confused - you're trying to adjust your primaries? You should only be able to change the luminousity of the primaries, not their chromaticity coordinates.


Really what you want to be doing is making sure that your whites are D65. There are an infinite set of coordinates for your primaries that can be mixed in the right proportion to make D65 white.


Mike
I'm using the ColorFacts CF-6000.


I've seen reviews where they show a CIE graph that has a reference point for r g b that forms a triangle. Also included in the graph are the actual coordinates for the primaries - if I understand correctly. Then the calibrater talks about how they managed to get their actual primaries to match those on the triangle. Am I not understanding this?


When I did this red in particular was way off. I was ble to change it. The Sharp 10K has a Color Management System that allows you to change lumenance, chroma, and hue for R,G,B,Y,C,M all separately. So does this in fact allow me to change my coordinates for the primaries?


I think so, because I was able to get red to line up perfectly on its place in the triangle. Most original post here was to ask whether anyone knew why I couldn't get blue and green to line up like I did with red.


Am I just looking at this wrong and this is not something I'm supposed to be tweaking/calibrating?


Regarding the white point, is that something you measure with any white field IRE or it needs to be a certain one?
 

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Discussion Starter · #6 ·
Quote:
Originally posted by wm
You cannot change the primaries. If you are getting different readings for them the probe is drifting or something else is wrong. Take dark frames often.
Hi - thanks for answering. What is the purpose then of the Sharp's CMS that allows you to set R,G,B,Y,C,M separately each for lumenance, chroma, and hue? How can I use ColorFacts to determine the optimal setting for that?


I think reds on the Sharp 10K are too "hot" ouf of the box. On the CIE chart it was pretty far down and to the right of the reference point. I used the red chroma, lumenance, and hue to get the red point to line up on the triangle at the right spot and now reds look great. Is this not adjusting the primary? Hope this is not a silly question - still learning a lot.


What I'm trying to figure out is how I can get blue and green to line up the same. Thanks.
 

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Discussion Starter · #7 ·
Quote:
Originally posted by mark haflich
I think we we get that book, Video Demystified, we will have the chromacity setting answers. Before that, you might want to give Tom Strade at Immersive a quick call, he owned a Sharp XV-Z10000 for a while and knows how to calibrate it. He essentially sold it to purchase a Yamaha because of several features (not calibration related) the Yamaha has that the Sharp doesn't. The Sharp XV-Z10000 is the calibration tweakers' King.
Hi Mark - has you book arrived yet? I'm curious whether its a lot of practical information or more centered on theory. I realize theory is very important but at the same time I'll trying to find a how-to type of guide.
 

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Actually, the ideal projection system *doesn't* match the SMTPE primaries - you really would like the primaries to be all the way in the corner. Your color gamut (i.e. the colors you can reproduce) are the colors inside that triangle. SMTPE-C I believe is just the measurements of the phosphors of some reference CRT - but that CRT is not the "perfect" display device.


The goal of calibrating your projector is:

1. Color balance - i.e. your gray scale is 6500 all the way from black to white

2. Luminance/gamma - i.e. 10 IRE has the right luminance, when compared to 20 IRE, 30 IRE, etc...


The Sharp's color management system is probably causing multiple primaries to appear together. So for RGB of 255,0,0, instead of just outputting red, I guess it allows you to mix in some G and/or B too.


Really I think you should set it so that Red is pure red, green is pure green, etc. Then calibrate your gray scale.


Mike
 

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Whoops. The first "we" was meant to be "when". Should get it this week sometime.


Now if I understand things correctly, and maybe I don't, the triangle reference points are not the same as for the RGB phospher cordinates in a CRT. Thus for a CRT, the phospher points are within the reference triangle and not coexistant with those points. A bulb projector has different points than the various phospher points. That has something to do with needing the calibration points for the bulb type in use. I am no exoert here, that is why I have purchased the book based on Tom Strade's recommendation. Really Eric, give Tom a call tomorrow, I am sure he will be glad to help. Then you can report back here what you learned. Tou can also call the Miliori guy, he will be glad to help too.
 

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Quote:
Originally posted by mflaster
Actually, the ideal projection system *doesn't* match the SMTPE primaries - you really would like the primaries to be all the way in the corner. Your color gamut (i.e. the colors you can reproduce) are the colors inside that triangle.
That would be true if we could take advantage of it, but remember that the video signals we are watching are encoded using a standard. That standard specifies the primaries for which the signal is generated. So if you change the primaries in your projector, you would have to translate the color information in the video signal accordingly, not a trivial task.


The primaries in a CRT projector are determined by the phosphors, and can be (and often are) corrected with filters. The primaries in a "bulb" projector (digital) are determined by the color filters used to produce them. It's really very much the same thing, two different methods of producing the primary colors that are then modulated to produce the image.


William
 

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G'day Ric,


Take a primaries reading and compare to the one I've attached below. This was of a Z9000 I calibrated about 6 months ago so your 10K should be quite close I would expect. It is my understanding that the co-ordinates of the triangle points are largely determined by the spectral characteristics of the bulb in use, and thus determine the gamut of colours that are reproduceable. Adding filters within the light path may help correct disproportionate levels of the R,G and B components needed to achieve good chromaticity at all greyscale levels for D65 (which was the case for example on the NEC LT150), but I found the Sharp didn't need that crutch.


As Mike stated above, if you concentrate on hitting that 6500K line from 0 IRE to 100 IRE, WHILE MAINTAINING THE CORRECT PROPORTIONS OF R,G AND B, you will have achieved the biggest part of your objective. Then you can play around with your gamma settings to change the image to suit YOUR preference.

http://www.users.bigpond.net.au/benn...00/Z9000_1.jpg


Cheers :)


Russ
 

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Discussion Starter · #12 ·
You mention "WHILE MAINTAINING THE CORRECT PROPORTIONS OF R,G AND B". That's my question - how do you know what the correct proportions are?


As mentioned the Sharp 10K red out of the box is just way to hot/fluorescent. What I want to do is set my red to the standard red that I should have. What steps do I take to do this via instrumention - as opposed to doing it by eye?


Achieving a flat grayscale from about 20 IRE to 100 IRE was quite simple once I figured out a couple of important tricks. But what has me know is how to dial in the color. I want to produce the truest r, g, and b. But how?


Here is a snapshot of my out of the box CIE chart, followed by the CIE chart *after* I mucked with the red lumenance, chroma, and hue in the Sharp CMS settings. This got the red to line up. But is this the correct reference red I want? I don't know.


Any why despite everything I try can't I get green and blue to line up? I was able to tweak CMS for red, so I would think I could do the same for g and b.


Lastly I include my post calibration grayscale temps.
 

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Discussion Starter · #13 ·
Here is my CIE Chart after I tweaked red in the CMS. Is this good? Reds look better, but is this what I want to do?
 

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Ric,


Comparing your two CIE charts, it appears that the CMS software you are using is somehow constricting the colour gamut at the Green and Red levels. Ideally you want as large a triangle as possible and as close to the RGB extremes as possible. My suggestion would be to revert back to the original settings that produced the first CIE chart.


Your RGB Levels graph would suggest that your greyscale is tracking nicely (very good in fact!), and that is what I meant by maintaining the correct proportions of R,G and B. The RGB Levels instrument in ColorFacts calculates and displays the required relative proportions needed as you are no doubt aware. Judging by the graphs themselves I would expect the picture to look pretty good at this stage.


Perhaps you need to explain what you mean by red being too hot/fluorescent. It may simply mean the signal coming out of your PC/DVD player has an incorrectly set saturation level. That may well give the image characteristic you are seeing.


Cheers :)


Russ
 

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Ok, I'll play the fool.


The PJ gamut original shows the colors the PJ CAN encompass.

The Gray gamut shows what the source material is constrained to.

Obviously the two are a bit different in some areas.


As you tweaked you constrained the red and since your "target" is

contained within the PJ gamut - you were able to hit it.


Your green "target" is outside the PJ gamut - you can't get there.

You will notice that you constrained the PJ green somewhat though.

Notice it too moved along within the PJ gamut.


If the tweaks allowed it you could constrain yourself to anywhere within

the original PJ gamut. You do notice however that 2 of your "target"

points are NOT contained within the original PJ gamut.

Unless the out-o-box setups was itself constrained, you won't

hit the "target".


Although there may have been some out-o-box constraint, I don't see it

expanding enough to fully include your "target". Again, if the PJ gamut

fully encloses your target, your done. If not, your done anyway.

As Benny says, you want as BIG and wide and open a gamut as you can get.


As far as running hot on the RED is concerned, don't confuse the

intensity of a "color" with it's chromaticity.



As always, I may have completely bollixed this up and if so --- oops !


EDIT {spacing }
 

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Yes, Jamin is correct. The Sharp "moves" the primaries by adding in additional colors. So it necessarily needs to stay in the original color triangle, where the primary points are from unmodified pure colors.


So you can match R, but not G and B.


Mike
 

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Discussion Starter · #18 ·
Quote:
Originally posted by benny

deally you want as large a triangle as possible and as close to the RGB extremes as possible. My suggestion would be to revert back to the original settings that produced the first CIE chart.
If I understand you correctly this sounds like a bit of a contradiction. I assume by RGB extremes you are referring to the reference points in the CIE chart.


If the triangle is as large as possible, then it could also be futher than the RGB extremes. So to be close as possible to the RGB extremes, the triangle would then not be as large as possible.


If you are saying that the triangle should be as large as possible, but also as close as possible to the RGB extremes then wouldn't my second CIE Chart be more ideal?


The settings that generated the second CIE chart produces the largest triangle while being as close to the points as possible. But since you're recommending I go back to the settings that generated the first CIE chart I must not be understanding your recommendation. Please exxplain further.

Quote:
Perhaps you need to explain what you mean by red being too hot/fluorescent. It may simply mean the signal coming out of your PC/DVD player has an incorrectly set saturation level. That may well give the image characteristic you are seeing.
What I mean about the reds is that they have way too much pop. Oversaturated sounds like the correct term. If you see a stop sign for example instead of it looking the color you'd expect, its reds are a bit too deep and to bright/glowing.


I know the issue is specific to the pj and not my other equipment or signals because I see this no matter what I'm watching - it happens with HDTV via my STB over component, DVD over component, and even with my HTPC DVD over DVI.


So is the condition I describe about my reds what you'd call over saturated? If so, which settings are appropriate for tweaking to resolve this, and most importantly how can one determine via ColorFacts what the level of Red actually is so that I can tweak it around until it hits its reference red with regards to saturation - not color temperate (I think those are different)?.


That has been my biggest question. I thought I was on target by trying to tweak the results in the CIE chart. But it sounds like people are saying that it is what it is and not to mess with it.


That is confusing too... For example I recall reading reviews where the calibrator said he tweaked to get the CIE chart to match the reference point. So it does sound like that is a legitimate calibration step. Thanks!
 

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Discussion Starter · #19 ·
OK, so I've been focused on trying to get my pj's CIE triangle lined up as close to possible to the reference SMTPC-E triangle.


Let's assume that I use the setting that generated the first CIE chart as Benny (Russ) suggests. Let's also assume I have near perfect grayscale tracking from 20-100 IRE at 6500.

With those assumptions in mind, is there any downside / negative effects from not having my triangle match the reference triangle?

If these triangles do not match, does that mean that my pj will not be able to display certain colors as the film producers intended? Or is it such that as long as I have perfect grayscale tracking at 6500 I'll see every color exactly as intended in a film (assuming of course the source material and signal allow this).


That's been my biggest concern with the calibration - I was thinking that if the CIE triangle from my pj did not match the reference triangle that some colors would not be able to be displayed properly. But I'm thinking that's probably not related as long as I have 6500 gray scale tracking? So then what's the downside if any of not matching the SMTPE-C triangle?
 

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Quote:
Originally posted by lovingdvd


With those assumptions in mind, is there any downside / negative effects from not having my triangle match the reference triangle?
As William says:
Quote:
remember that the video signals we are watching are encoded using a standard.
So if any of your primary points don't match the standard by which the video was encoded, then your colors won't be exactly accurate.


In other words, all your grays could be fine, but for a pure green signal, for example, the DVD author expects to see one chromaticity pair, but your projector will actually put out a different pair. So they won't look identical.


But I'm not sure how noticeable this would actually be.


Mike
 
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