Is it possible to calibrate a display using a high quality digital camera? - Page 7 - AVS Forum
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post #181 of 208 Old 10-03-2010, 06:37 PM
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why are all you nay-sayers here? The guy has a passion... and he's not so far wrong... any improvement is good, and if he sees any improvement, then why beat him over the head? let him enjoy the improvement he sees... you all say that his eyes are lying - but if he likes the lie, so what? Need you beat him to a pulp to prove he's "wrong" in his pleasure????

Geeeezzz!

Lighten Up !!

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post #182 of 208 Old 10-03-2010, 06:46 PM
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Originally Posted by morphinapg View Post

My "belief" is my hypothesis in this experiment. I want to prove it, and I think I think I will prove it, but I just can't right now. My "belief" is more of an educated guess, rather than a completely random guess. There is reasoning behind my hypothesis, however currently I am incapable of proving or disproving that hypothesis.

You're simply not understanding that you're wrong - why you're wrong has been explained a myriad of times, and you don't want to listen. Instead you go on about your beliefs.

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Wouldn't sets calibrated to different standards theoretically have different ranges of colors they are capable of producing?

No, why would you say that?

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Anyway, I was referring to the actual grey point themselves. A color of D93 just seems too blue to be grey.

I've already explained why "true" white doesn't exist, so you're statements about which white seems right is completely irrelevant. Further, most people actually tend to find "cooler" whites to be "whiter" even though - once again - they're simply different whites, not better.

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Yes, you could compensate the source material to appear proper on a D93 monitor (by making the source colors warmer), but that's essentially the same as calibrating the display to D65 and showing D65 material, so what's the point? A color that would register on a meter as D65 on the D65 set would still register as D65 on the D93 set as long as the source material was produced for the corresponding color temperatures.

What do you think the mastering process is all about? You take the source material and alter it in all kinds of ways so that you achieve a desired look. Reference white is not important because of the kind of white it defines intrinsically; it is simply important that the same reference is used throughout the chain. Why we use D65 and not some other standard, I don't know. Whatever the answer, it doesn't really matter as it IS the standard that we use and, if you want to calibrate, it's what you should be using as your white point standard.


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Originally Posted by morphinapg View Post

I'm not doubting the value of calibration, and I agree that on paper everything makes sense, it's just, what's the point of "accuracy" if our eyes adapt anyway? For example, let's say I have a calibrated D65 screen and I stare at a greyscale pattern for a few minutes, and then I go into another room, which has a D93 screen, uncalibrated, and showing the same source grey pattern. I stare at this screen for a few minutes. Now, to my eyes, both screens look virtually identical. Obviously I would be able to tell a difference with them side by side, but when separated like this our eyes really can't tell the difference, they appear identical.

As for that example of skin appearing too pale, that would only happen when comparing it with a calibrated display. When watching the uncalibrated cooler display, our eyes would adapt and make the image seem warmer than it really is, in effect making the skin look just fine, and not too pale. On paper it makes sense, I just don't know if the reality is as clear as it would seem.

I guess calibration, to me, is more of a "well I guess I'll do it because theoretically it makes sense" sort of thing. I just don't know if it's as important as I've always thought it was.

These questions have been thoroughly answered in other sticky threads in this forum. I'd highly suggest that you go read them. However, if you're questioning the reason for calibration, why bother with the process if you're not even going to use an accepted standard to start with?

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post #183 of 208 Old 10-03-2010, 06:58 PM
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Originally Posted by jimwhite View Post

why are all you nay-sayers here? The guy has a passion... and he's not so far wrong... any improvement is good, and if he sees any improvement, then why beat him over the head? let him enjoy the improvement he sees... you all say that his eyes are lying - but if he likes the lie, so what? Need you beat him to a pulp to prove he's "wrong" in his pleasure????

Geeeezzz!

Lighten Up !!

This is the calibration forum. Calibration means accuracy, standards, and understanding the basics of color science and the human visual system. He came here and asked a question - no fault in that - but when he got an answer he didn't like, he simply ignored experts and continued to say that he believes he's right despite a litany of data that contradicted him.

No one has ever said that he can't enjoy the results of what he's done, or that what he's done is wrong for him personally. However we have said that what he's done is no more likely to produce a D65 reference for "free" than eyeballing his greyscale settings.

Why are people like you trying to paint this as some poor guy being bullied for enjoying his set up?

There are 10 types of people: those who understand binary, and those who don't.

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post #184 of 208 Old 10-03-2010, 07:12 PM
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Originally Posted by HogPilot View Post

Why are people like you trying to paint this as some poor guy being bullied for enjoying his set up?

There it is...


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post #185 of 208 Old 10-03-2010, 07:15 PM
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This post makes it #185. There should have been a total of 2 with the second one being one word - "NO"

I stick around for the humor.

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post #186 of 208 Old 10-03-2010, 07:31 PM
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Originally Posted by jimwhite View Post

There it is...


You so eloquently rebutted all of the logical arguments I've laid out. Who cares about facts and learning when we can all just insist we're right and feel good about ourselves?

There are 10 types of people: those who understand binary, and those who don't.

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post #187 of 208 Old 10-03-2010, 08:38 PM - Thread Starter
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Originally Posted by HogPilot View Post

You're simply not understanding that you're wrong - why you're wrong has been explained a myriad of times, and you don't want to listen. Instead you go on about your beliefs.

No, why I could be wrong has been explained many times. There's no way to know for sure without proper testing and measurements.

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Originally Posted by HogPilot View Post

I've already explained why "true" white doesn't exist, so you're statements about which white seems right is completely irrelevant. Further, most people actually tend to find "cooler" whites to be "whiter" even though - once again - they're simply different whites, not better.

Isn't there a set scientific standard of what constitutes white? There can't be multiple colors that are scientifically regarded as the same color, that makes no sense. Those other colors might be close to white, and our eyes may be able to adapt to them to view them as white, but that doesn't mean they are white.

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What do you think the mastering process is all about? You take the source material and alter it in all kinds of ways so that you achieve a desired look. Reference white is not important because of the kind of white it defines intrinsically; it is simply important that the same reference is used throughout the chain. Why we use D65 and not some other standard, I don't know. Whatever the answer, it doesn't really matter as it IS the standard that we use and, if you want to calibrate, it's what you should be using as your white point standard.

We use D65 because it's average daylight, the average color we see as white in nature. If we lived in a system with a red star, we'd probably have a reference white of a much warmer color temperature than D65.

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These questions have been thoroughly answered in other sticky threads in this forum. I'd highly suggest that you go read them. However, if you're questioning the reason for calibration, why bother with the process if you're not even going to use an accepted standard to start with?

As I said, theoretically it makes sense, but that is disregarding the human eye's adaptive qualities. I'll read the stickies and see if it helps me further.

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Originally Posted by HogPilot View Post

This is the calibration forum. Calibration means accuracy, standards, and understanding the basics of color science and the human visual system. He came here and asked a question - no fault in that - but when he got an answer he didn't like, he simply ignored experts and continued to say that he believes he's right despite a litany of data that contradicted him.

No one has ever said that he can't enjoy the results of what he's done, or that what he's done is wrong for him personally. However we have said that what he's done is no more likely to produce a D65 reference for "free" than eyeballing his greyscale settings.

Why are people like you trying to paint this as some poor guy being bullied for enjoying his set up?

I never said I was right, and I never said I was achieving a D65 reference. I've only said I think this process has helped, and I think it has brought my greyscale closer to D65, but not all the way there. Who knows, maybe it only brought me 10% there for all I know. Maybe my set was closer to D93, and maybe now it's closer to D85. I don't know, I just think it's closer to D65, that's all.
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post #188 of 208 Old 10-03-2010, 09:13 PM
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lololololololol

You are such an obnoxious troll morph, or morgue, or whatever you call yourself. This is "supposed" to be a subforum about real life serious calibration. Your equipment, may, on a huge long shot, be accurate. lolololololololooololo Sorry, can't help myself. It's not. It's a joke, right? No one could write the longish obsessive posts that you do without wringing his hands in gleeful playfulness.

moderators - time to lock this thread?

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post #189 of 208 Old 10-03-2010, 09:26 PM - Thread Starter
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Originally Posted by buzzard767 View Post

lololololololol

You are such an obnoxious troll morph, or morgue, or whatever you call yourself. This is "supposed" to be a subforum about real life serious calibration. Your equipment, may, on a huge long shot, be accurate. lolololololololooololo Sorry, can't help myself. It's not. It's a joke, right? No one could write the longish obsessive posts that you do without wringing his hands in gleeful playfulness.

moderators - time to lock this thread?

I'm not a troll, I thought the images I posted proved that. I never said this was accurate. This subforum is about calibration, which is used to achieve better color on a TV. I'm attempting to get better color out of my TV with unconventional methods. I see nothing wrong with this thread. If this thread is annoying you, don't post in it anymore and unsubscribe from it if you're subscribed. Not that hard.
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post #190 of 208 Old 10-04-2010, 03:17 AM
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Originally Posted by morphinapg View Post

No, why I could be wrong has been explained many times. There's no way to know for sure without proper testing and measurements.

It's random chance, and that's not calibration, no matter how much you want it to be. So no, what you're doing is not calibration.

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Originally Posted by morphinapg View Post

Isn't there a set scientific standard of what constitutes white? There can't be multiple colors that are scientifically regarded as the same color, that makes no sense. Those other colors might be close to white, and our eyes may be able to adapt to them to view them as white, but that doesn't mean they are white.

So here you are, guessing, rather than knowing. Again, I suggest you do some more reading.

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Originally Posted by morphinapg View Post

We use D65 because it's average daylight, the average color we see as white in nature. If we lived in a system with a red star, we'd probably have a reference white of a much warmer color temperature than D65.

D65 does is not anywhere close to direct sunlight. It's approximately related to overcast light. The color of our star - which is yellow - has little to do with D65. Again, you're just throwing stuff out there and guessing rather than studying real color science.

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I'm not a troll, I thought the images I posted proved that. I never said this was accurate.

When you patently disregard those who know considerably more than you about this subject, you come off as a troll.

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Originally Posted by morphinapg View Post

This subforum is about calibration,

Yes.

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Originally Posted by morphinapg View Post

which is used to achieve better color on a TV.

No. Calibration is about comparing your display to a KNOWN standard and trying to match it to that standard as close as possible. What you are doing is not calibration. You're stabbing in the dark, hoping that your results are better than what you started with. You might get lucky and you might not. Why do you continue to insist that what you're doing is somehow related to calibration when it's been explained time after time that it's not?

There are 10 types of people: those who understand binary, and those who don't.

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post #191 of 208 Old 10-04-2010, 10:47 AM - Thread Starter
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It's random chance, and that's not calibration, no matter how much you want it to be. So no, what you're doing is not calibration.

Never said it was calibration. Tried to change the thread title but it didn't work. Also, it's not random. It's controlled, so I'll get the same result every time. Whether that result is better or worse can only be determined either by your eyes (which I believe it's better) or more accurately with a meter, which i don't have yet.

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So here you are, guessing, rather than knowing. Again, I suggest you do some more reading.

All I can do is make educated guesses based on what I know. Several colors being defined as white simply seemed illogical to me.

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D65 does is not anywhere close to direct sunlight. It's approximately related to overcast light. The color of our star - which is yellow - has little to do with D65. Again, you're just throwing stuff out there and guessing rather than studying real color science.

I never said direct sunlight. I said average daylight, which can be sunny, cloudy, partly cloudy, etc. It's the average, and that's very much determined by our sun. Also, I watched a show on the history channel recently that said our sun is not yellow. It looks yellow at the horizon due to color filtering in our atmosphere, and it has a peak of yellow, but the overall color it emits is white.

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When you patently disregard those who know considerably more than you about this subject, you come off as a troll.

I don't disregard anything. It seems like you disregard the possibility that this can help. Yes, there were a few factors I didn't do as good as I could have, mainly the color of paper, but if those factors are more controlled, why would you still consider it random chance? It's completely controlled, whether that results in better color or worse color can not be determined at this time by me. But if you have a good quality digital camera, a neutral grey card, and a meter, go a head and try this yourself and give us results instead of automatically shooting something down when there's a chance it can help.

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No. Calibration is about comparing your display to a KNOWN standard and trying to match it to that standard as close as possible. What you are doing is not calibration. You're stabbing in the dark, hoping that your results are better than what you started with. You might get lucky and you might not. Why do you continue to insist that what you're doing is somehow related to calibration when it's been explained time after time that it's not?

Which is what I'm trying to do. I may or may not have succeeded, but that doesn't change the fact that it's what I'm trying to do. I'm trying to get as close to that standard as I can with the tools I have. I know I can't get as close as a real calibration, but the hypothesis is that I have gotten closer.

I find it strange that no one here has helped me test my hypothesis. I don't have a meter, I can't do that testing right now. There's a chance it has improved, so why don't the people with meters and good digital cameras help do the testing? I don't know.

I don't see how you people can so quickly disregard the possibility of this helping. As long as your light source was close to D65, and your paper/card was close to D65, and the camera was white balanced to that, your camera will always be able to calibrate within a certain range of error. The meters you use also have a range of error, it's just much smaller than a digital camera would have.

For example, a meter might have a 0.5% range of error (not a real figure, just an example) and a camera might have a range of error of 5%. The meter would get you up to at least within 0.5% of the standard, possibly closer. The camera will get you at least within 5% of the standard, possibly closer. Every camera is likely to have a different range of error, just as every different meter probably does as well.

These are facts, these are not debatable. What is debatable is whether my TV's color was already outside my camera's range of error, or inside that range. That would determine whether or not my camera has improved my color or not.
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post #192 of 208 Old 10-04-2010, 11:40 AM
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i never said...
i believe...
educated guesses....
several colors being defined as white simply seemed illogical to me
i never said...direct sunlight but average daylight that's far to avarage..
But if you have a good quality digital camera your camera is not a good quality one because it's not shooting RAW
Neutral greycard... that's one thing that you need for instance and... ONLY THAN you can "calibrate" your cam to shoot neutral grey in presence of THAT clowded or sunny day ( do that ring a bell now???) so nothing to do with D65.....
Even the cheaper meters do not have THAT high 0,5 % error so that's a bad example (you should read more about meters)These are facts, these are not debatable you are not showing facts but educated guesses(these are your own words)

Have you ever trying to shoot your "white" paper under different daylight ?? , try that and use your image program to see the different RGB

If that does not result in different RGB your camera is doing something with the white balance wich prove its not possible to set CLOSER to D65.
If it does result in different RGB on the same paper THAT also is a prove you are aiming closer to D65 with different whitebalance thus your camera is not going to help you getting closer to D65 ( i am NOT using the word calibrating).

So both is not gonna help you to aim closer to D65 ( ring ring )
Meters are calibrated before coming to the store and that is someting that you can't do with random daylight ( whatever that is )


regards,


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Never said it was calibration. Tried to change the thread title but it didn't work. Also, it's not random. It's controlled, so I'll get the same result every time. Whether that result is better or worse can only be determined either by your eyes (which I believe it's better) or more accurately with a meter, which i don't have yet.


All I can do is make educated guesses based on what I know. Several colors being defined as white simply seemed illogical to me.


I never said direct sunlight. I said average daylight, which can be sunny, cloudy, partly cloudy, etc. It's the average, and that's very much determined by our sun. Also, I watched a show on the history channel recently that said our sun is not yellow. It looks yellow at the horizon due to color filtering in our atmosphere, and it has a peak of yellow, but the overall color it emits is white.


I don't disregard anything. It seems like you disregard the possibility that this can help. Yes, there were a few factors I didn't do as good as I could have, mainly the color of paper, but if those factors are more controlled, why would you still consider it random chance? It's completely controlled, whether that results in better color or worse color can not be determined at this time by me. But if you have a good quality digital camera, a neutral grey card, and a meter, go a head and try this yourself and give us results instead of automatically shooting something down when there's a chance it can help.


Which is what I'm trying to do. I may or may not have succeeded, but that doesn't change the fact that it's what I'm trying to do. I'm trying to get as close to that standard as I can with the tools I have. I know I can't get as close as a real calibration, but the hypothesis is that I have gotten closer.

I find it strange that no one here has helped me test my hypothesis. I don't have a meter, I can't do that testing right now. There's a chance it has improved, so why don't the people with meters and good digital cameras help do the testing? I don't know.

I don't see how you people can so quickly disregard the possibility of this helping. As long as your light source was close to D65, and your paper/card was close to D65, and the camera was white balanced to that, your camera will always be able to calibrate within a certain range of error. The meters you use also have a range of error, it's just much smaller than a digital camera would have.

For example, a meter might have a 0.5% range of error (not a real figure, just an example) and a camera might have a range of error of 5%. The meter would get you up to at least within 0.5% of the standard, possibly closer. The camera will get you at least within 5% of the standard, possibly closer. Every camera is likely to have a different range of error, just as every different meter probably does as well.

These are facts, these are not debatable. What is debatable is whether my TV's color was already outside my camera's range of error, or inside that range. That would determine whether or not my camera has improved my color or not.


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post #193 of 208 Old 10-04-2010, 12:00 PM - Thread Starter
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Wow your post is ugly as hell but let's see what I can make of it

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i never said...direct sunlight but average daylight that's far to avarage..

It's supposed to be average, that's the point. D65 is the average color of daylight in the world, and is closest to an overcast day (mid day is better because too early or too late would produce a much warmer image due to the color filtering of the horizon.)

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But if you have a good quality digital camera your camera is not a good quality one because it's not shooting RAW

RAW wouldn't help me anyway. I need to be able to white balance the camera, and RAW mode disables that. RAW mode would help with the exposure, but that's it. I can compensate for that by using a lower exposure.

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Neutral greycard... that's one thing that you need for instance and... ONLY THAN you can "calibrate" your cam to shoot neutral grey in presence of THAT clowded or sunny day ( do that ring a bell now???) so nothing to do with D65.....

It'll be pretty close to D65, even if it's slightly off.

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Even the cheaper meters do not have THAT high 0,5 % error so that's a bad example (you should read more about meters)

Did you miss the part where I just gave a random example, not basing the number on any facts. The actual number wasn't important in that example, just the fact that is was much lower than the camera's number. Good job missing the point completely.

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These are facts, these are not debatable you are not showing facts but educated guesses(these are your own words)

The educated guess was for a completely different issue. It's a fact that a camera will have a range of error bigger than a meter, and it's a fact that any TV with color off by a margin greater than the camera's range of error will be improve when using the camera. Those are facts and not debatable.
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post #194 of 208 Old 10-04-2010, 12:20 PM
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morphinapg,

I think the assumption that you're making here is that Warm/Warm2 on most sets is drastically different from D65.

The truth is that the warmest setting is generally ball park D65.

If you are trying to hit the pitchers mound and you start in the ballpark, but your accuracy with the camera is the size of another ballpark, there is a very good chance your answer ends up way outside the ballpark (it could end up closer, but your can't be sure at all).

You're right that high quality CCD's sensors with the right electronics could eaisly be used for calibration. But the package would need to be calibrated.

I just grabbed a sheet of paper off my printer and checked it with my i1Pro, it's color temp is 7137, and is x,y location is x=.3044,y=.3155. Which is easily as close as any TV is out of the box.

What our doing in theory can work, but you'd need some sort of control to calibrate the system to. Currently you lack that control. So when you boil your comments down to a proffesional calibrator, they basically sound like, "I made a guess, and I'm sure that it's better than when I started". I say this because you guess that the paper is able to reflect the complete spectrum of light evenly, you guess that the daylight in your location is D65, you guess that setting up your camera to D65 is actually accurate (To this point why not believe that Warm is properly calibrated in your TV) and you guess that the RGB filters in the camera match the XYZ curve for the Standard obeserver function.

You have 4 extremely important variables in your equation that are unkown. Sure they maybe in the ballpark, but so is the TV from the factory.

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post #195 of 208 Old 10-04-2010, 12:27 PM
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post #196 of 208 Old 10-04-2010, 01:20 PM
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PlasmaPZ80U - agreed. Things have been explained a myriad of times, and the OP is clearly not interested in listening or learning. Everyone just needs to leave this thread be so it can die the quiet death it deserves.

There are 10 types of people: those who understand binary, and those who don't.

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post #197 of 208 Old 10-04-2010, 05:58 PM
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Everyone just needs to leave this thread be....

After you've posted to it at least 18 times.

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post #198 of 208 Old 10-04-2010, 06:03 PM
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Originally Posted by dlarsen View Post

After you've posted to it at least 18 times.

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Ha, touche salesman I think by this point your average lurker will be able to see what's up. The horse has been thoroughly pulverized, so no sense in feeding any annoying creatures any more.

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post #199 of 208 Old 10-04-2010, 08:26 PM - Thread Starter
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Originally Posted by sotti View Post

morphinapg,

I think the assumption that you're making here is that Warm/Warm2 on most sets is drastically different from D65.

The truth is that the warmest setting is generally ball park D65.

If you are trying to hit the pitchers mound and you start in the ballpark, but your accuracy with the camera is the size of another ballpark, there is a very good chance your answer ends up way outside the ballpark (it could end up closer, but your can't be sure at all).

You're right that high quality CCD's sensors with the right electronics could eaisly be used for calibration. But the package would need to be calibrated.

I just grabbed a sheet of paper off my printer and checked it with my i1Pro, it's color temp is 7137, and is x,y location is x=.3044,y=.3155. Which is easily as close as any TV is out of the box.

What our doing in theory can work, but you'd need some sort of control to calibrate the system to. Currently you lack that control. So when you boil your comments down to a proffesional calibrator, they basically sound like, "I made a guess, and I'm sure that it's better than when I started". I say this because you guess that the paper is able to reflect the complete spectrum of light evenly, you guess that the daylight in your location is D65, you guess that setting up your camera to D65 is actually accurate (To this point why not believe that Warm is properly calibrated in your TV) and you guess that the RGB filters in the camera match the XYZ curve for the Standard obeserver function.

You have 4 extremely important variables in your equation that are unkown. Sure they maybe in the ballpark, but so is the TV from the factory.

Did you measure the paper under D65 light? Paper doesn't emit light on its own so you would be measuring the color of whatever light hits it x the color of the paper.

What you're saying about unknown variables is correct, and I'll make sure to get a more proper D65 reference card to work with, but I think all the other variables are pretty much given that they'd be within acceptable range for me. Overcast daylight is pretty damn close to D65. I know my camera white balances properly, I've tested that to make sure. I know the camera doesn't have the same filter curves, but that's why there's a greater range of error on the camera than the meters.

btw, my camera did determine that "Warm 2" was the closest color temperature setting, but there was still quite a way to go after that.

The default values for RGB Cutoff and Drive were all 32, and this is what I came up with after the process:

Cutoff:
R=44
G=27
B=33

Drive:
R=60
G=29
B=35

So as you can see, while Warm 2 got me the closest of the presets, and I used it as a base, there was still more to go from there.
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post #200 of 208 Old 10-04-2010, 08:44 PM
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Quote:
Originally Posted by morphinapg View Post

Did you measure the paper under D65 light? Paper doesn't emit light on its own so you would be measuring the color of whatever light hits it x the color of the paper.

What you're saying about unknown variables is correct, and I'll make sure to get a more proper D65 reference card to work with, but I think all the other variables are pretty much given that they'd be within acceptable range for me. Overcast daylight is pretty damn close to D65. I know my camera white balances properly, I've tested that to make sure. I know the camera doesn't have the same filter curves, but that's why there's a greater range of error on the camera than the meters.

btw, my camera did determine that "Warm 2" was the closest color temperature setting, but there was still quite a way to go after that.

The default values for RGB Cutoff and Drive were all 32, and this is what I came up with after the process:

Cutoff:
R=44
G=27
B=33

Drive:
R=60
G=29
B=35

So as you can see, while Warm 2 got me the closest of the presets, and I used it as a base, there was still more to go from there.

Yes the paper was illuminated with a refrence light source. The tool was an i1Pro, in reflectance mode it blocks out all light and then illuminates the target with a reference light source. I write color calibration software for spectracal and have access to everything up to a Konica Minolata CS2000.

The only thing you know is that you made your set redder and less green, you have no idea where you are in relation to your target though since every scientific step in your process is an unkown.

I've never seen a TV in warm mode need double the amount of red to get to D65, it's likely your set is overly red now. You're dealing with two in the ballpark sized guesses, when you really need to be inside the baseball diamond to even be considered close to the pitchers mound.

The catch22 of calibrating with a camera is you need the tools to do calibration to accurately setup the camera.

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post #201 of 208 Old 10-04-2010, 09:37 PM
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Quote:
Originally Posted by morphinapg View Post

....I'll make sure to get a more proper D65 reference card to work with....

There's no such animal. What would be needed is a completely neutral reflective surface- one which reflects all colors equally- such as a Kodak 18% gray card or a Munsell neutral gray reference sample.

Then you would need a D65 reference illuminant that is the same white point as video white. You can't use just any old official CIE D65 illuminant, either. The standard range of tolerance to qualify as CIE D65 in the lighting industry covers a narrow oval on the CIE chromaticity diagram, running from approximately 5500K up to around 7500K. You need a CIE D65 illuminant that is nearer the video white point at x.313/y.329. The closest solution I know of is an Ideal-Lume Pro bias light. I have provided them to NIST, THX, the ISF, Deluxe, Technicolor, Dolby Labs, Joe Kane Productions, etc. We filter the lamp used in the product to within +/-.005 x/y.

I have been watching the course of this thread and just couldn't let this issue go uncorrected. This discussion has been akin to passing an automobile wreck, or a house fire, which I usually am tempted to slow down to watch. It's a common human weakness.

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.
A Lion AV Consultants Affiliate

"Advancing the art and science of electronic imaging"
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post #202 of 208 Old 10-04-2010, 10:04 PM
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Quote:
Originally Posted by GeorgeAB View Post

There's no such animal. What would be needed is a completely neutral reflective surface- one which reflects all colors equally- such as a Kodak 18% gray card or a Munsell neutral gray reference sample.

Then you would need a D65 reference illuminant that is the same white point as video white. You can't use just any old official CIE D65 illuminant, either. The standard range of tolerance to qualify as CIE D65 in the lighting industry covers a narrow oval on the CIE chromaticity diagram, running from approximately 5500K up to around 7500K. You need a CIE D65 illuminant that is nearer the video white point at x.313/y.329. The closest solution I know of is an Ideal-Lume Pro bias light. I have provided them to NIST, THX, the ISF, Deluxe, Technicolor, Dolby Labs, Joe Kane Productions, etc. We filter the lamp used in the product to within +/-.005 x/y.

I have been watching the course of this thread and just couldn't let this issue go uncorrected. This discussion has been akin to passing an automobile wreck, or a house fire, which I usually am tempted to slow down to watch. It's a common human weakness.

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.
A Lion AV Consultants Affiliate

"Advancing the art and science of electronic imaging"

And this is my point. If you had an ideal lume and a munsell gray card, then you could take a picutre of that. That is a know quantity. Now we have captured what D65 looks like, so you can calibrate the camera for that to be 255, 255, 255. Now when you go to calibrate your TV at least the only unkown factor is the difference in the CCD filters between the spectrum of the TV vs the Lamp. Now we'd be inside of the ballpark at least on the playing feild.

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post #203 of 208 Old 10-05-2010, 12:52 AM - Thread Starter
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Originally Posted by sotti View Post

Yes the paper was illuminated with a refrence light source. The tool was an i1Pro, in reflectance mode it blocks out all light and then illuminates the target with a reference light source. I write color calibration software for spectracal and have access to everything up to a Konica Minolata CS2000.

The only thing you know is that you made your set redder and less green, you have no idea where you are in relation to your target though since every scientific step in your process is an unkown.

I've never seen a TV in warm mode need double the amount of red to get to D65, it's likely your set is overly red now. You're dealing with two in the ballpark sized guesses, when you really need to be inside the baseball diamond to even be considered close to the pitchers mound.

The catch22 of calibrating with a camera is you need the tools to do calibration to accurately setup the camera.

This TV was very badly green/blue tinted, and I noticed that long before doing this procedure, so it's not strange that I had to increase the red so much. This TV really isn't a great TV. In fact, it's an old CRT HDTV from 2004 that I'm only using because my LCD died last month. I have to use this until around the end of the year, when I'm buying a new tv. This TV was always bad since i got it, it was a floor model and had a lot of picture problems.


Quote:
Originally Posted by GeorgeAB View Post

There's no such animal. What would be needed is a completely neutral reflective surface- one which reflects all colors equally- such as a Kodak 18% gray card or a Munsell neutral gray reference sample.

Then you would need a D65 reference illuminant that is the same white point as video white. You can't use just any old official CIE D65 illuminant, either. The standard range of tolerance to qualify as CIE D65 in the lighting industry covers a narrow oval on the CIE chromaticity diagram, running from approximately 5500K up to around 7500K. You need a CIE D65 illuminant that is nearer the video white point at x.313/y.329. The closest solution I know of is an Ideal-Lume Pro bias light. I have provided them to NIST, THX, the ISF, Deluxe, Technicolor, Dolby Labs, Joe Kane Productions, etc. We filter the lamp used in the product to within +/-.005 x/y.

I have been watching the course of this thread and just couldn't let this issue go uncorrected. This discussion has been akin to passing an automobile wreck, or a house fire, which I usually am tempted to slow down to watch. It's a common human weakness.

Best regards and beautiful pictures,
G. Alan Brown, President
CinemaQuest, Inc.
A Lion AV Consultants Affiliate

"Advancing the art and science of electronic imaging"

Well that's what I meant by the reference card. I'm not going to go as far as getting a D65 light though as I believe I can get a "close enough" reference light given the proper weather conditions outside. It may not be D65, but for me it's close enough for now, until I get a meter for a more proper calibration later. The idea of this experiment was to use what I already have. The grey card is probably cheap enough to not really qualify as an expense for this experiment, so I can probably get that.

It might be of note that using my cameras default 6500K setting has my paper showing as almost perfectly grey under the same sky conditions as before. However, I didn't trust presets when doing this as I figured they could drift over time.
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post #204 of 208 Old 10-05-2010, 05:04 AM
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Actually you will do better just buying a high CRI 6500K lamp than with daylight. Trust me, I have experimented with it. George is right, the IdealLume is the closest that you will find. He does his homework. The fact is, however, that you are likely to get closer with other lamps than with daylight, which is VERY variable.

I think the misunderstanding of the problems here goes back to the fundamentals of color science. When we match colors, we are dealing with a spectrum of light. Our eyes, the sensors in light meters, and the sensors in cameras all see that spectrum differently AND different displays (between technologies and even within the same model) and lamps produce different spectra. The meters we use in calibration account for this by using filters that attempt to match the Standard Observer functions, sample enough frequencies to get an actual spectral density, or some combination of the two with calibration tables to correct for response across the spectrum. Unless you know what the process is for getting from the light to the data that the sensor collects you just don't know what the numbers mean in terms of the color of the light collected. That is why we have meters and software designed for measuring color.

You said in the beginning that you did not know anything about X,Y,& Z and only knew about RGB. Since that point, in spite of being told many time that there is more to measuring color than you thought, you still don't seem to get it. What you assume are references, like daylight, or what you think you see, are not references at all. What you think are measurements, like the values you get from your camera, are not measurements of what you need. Until you start with a reference, you just will not know where you are. And until you learn the basic science, this thread will continue.

Alan is right again regarding the train wreck. I have made fun of your intransigence enough. This is my final explanation and comment on the matter. When you get a measurement, please post the results comparing your current settings and the measurements with a reference device. Just do not assume that the results will be any more repeatable than a visual comparison, and even if they turn out to be close for your display technologyand your camera , do not assume that they generalize to others, until you do the experiments to find out.

Yes, calibration is important...every user should be calibrated.

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post #205 of 208 Old 10-05-2010, 09:32 AM
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Originally Posted by morphinapg View Post


It might be of note that using my cameras default 6500K setting has my paper showing as almost perfectly grey under the same sky conditions as before. However, I didn't trust presets when doing this as I figured they could drift over time.

That's the point!

Camera's do that, they take the whitest thing they see, and make that color white (just like your eye). That's why this "experiment" doesn't work.

Camera's are designed to be perceptual.
Colorimeters are designed to be objective.

You need objective references to calibrate.

Do you need me to go measure daylight to see how far off it is? The color of daylight varies as much as anything else.

On a 2004 CRT that is dying, I'd likely agree that the set may be so far off that you are simply in the city and not the ballpark. But your results using your camera are likely no better than holding the paper up next to the screen and using that as a reference and tweaking by eye.

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post #206 of 208 Old 10-05-2010, 11:11 AM - Thread Starter
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Originally Posted by lcaillo View Post

Actually you will do better just buying a high CRI 6500K lamp than with daylight. Trust me, I have experimented with it. George is right, the IdealLume is the closest that you will find. He does his homework. The fact is, however, that you are likely to get closer with other lamps than with daylight, which is VERY variable.

I think the misunderstanding of the problems here goes back to the fundamentals of color science. When we match colors, we are dealing with a spectrum of light. Our eyes, the sensors in light meters, and the sensors in cameras all see that spectrum differently AND different displays (between technologies and even within the same model) and lamps produce different spectra. The meters we use in calibration account for this by using filters that attempt to match the Standard Observer functions, sample enough frequencies to get an actual spectral density, or some combination of the two with calibration tables to correct for response across the spectrum. Unless you know what the process is for getting from the light to the data that the sensor collects you just don't know what the numbers mean in terms of the color of the light collected. That is why we have meters and software designed for measuring color.

You said in the beginning that you did not know anything about X,Y,& Z and only knew about RGB. Since that point, in spite of being told many time that there is more to measuring color than you thought, you still don't seem to get it. What you assume are references, like daylight, or what you think you see, are not references at all. What you think are measurements, like the values you get from your camera, are not measurements of what you need. Until you start with a reference, you just will not know where you are. And until you learn the basic science, this thread will continue.

Alan is right again regarding the train wreck. I have made fun of your intransigence enough. This is my final explanation and comment on the matter. When you get a measurement, please post the results comparing your current settings and the measurements with a reference device. Just do not assume that the results will be any more repeatable than a visual comparison, and even if they turn out to be close for your display technologyand your camera , do not assume that they generalize to others, until you do the experiments to find out.

I'm sure a 6500K lamp would be more accurate than using daylight, but this experiment is about achieving the best color I can without spending any extra money.


Quote:
Originally Posted by sotti View Post

That's the point!

Camera's do that, they take the whitest thing they see, and make that color white (just like your eye). That's why this "experiment" doesn't work.

Camera's are designed to be perceptual.
Colorimeters are designed to be objective.

You need objective references to calibrate.

Do you need me to go measure daylight to see how far off it is? The color of daylight varies as much as anything else.

On a 2004 CRT that is dying, I'd likely agree that the set may be so far off that you are simply in the city and not the ballpark. But your results using your camera are likely no better than holding the paper up next to the screen and using that as a reference and tweaking by eye.

It sounds like you're thinking of auto white balance which I didn't use. I used a custom white balance. However, it would be interesting to see what your measurement of daylight reads, under the same conditions: Mid-day, overcast but still sunny (aka clouds not too dark, just dark enough to diffuse the sun's rays) You could also try measurements in other conditions and report which ones are closest to D65, that could definitely help. Holding a paper against my screen wouldn't help as the light in my room is very warm and so that would result in an overly warm color temperature.
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post #207 of 208 Old 10-18-2010, 06:03 AM
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I have read D65 is not daylight. Daylight is D50, D55, D65, or D75 depending on the time of day and sky conditions. A sunny day is apparently closer to 5600. D65 is allegedly light reflected off snow on an overcast day. So the season of calibration by eye or camera will soon be upon us.
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post #208 of 208 Old 10-18-2010, 01:04 PM - Thread Starter
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I have read D65 is not daylight. Daylight is D50, D55, D65, or D75 depending on the time of day and sky conditions. A sunny day is apparently closer to 5600. D65 is allegedly light reflected off snow on an overcast day. So the season of calibration by eye or camera will soon be upon us.

Interesting about the snow, I would have thought snow would reflect a higher color temperature. Though I was saying D65 was "average" daylight, which does cover a large variety of ranges, which is why I chose an overcast day like I said before, since Wikipedia said that overcast was closest to D65.
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