Is it possible to calibrate a display using a high quality digital camera? - Page 7

Originally Posted by morphinapg

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.

Originally Posted by morphinapg

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

Originally Posted by morphinapg

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

Originally Posted by morphinapg

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.

Originally Posted by morphinapg

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.

Originally Posted by jimwhite

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 !!

Originally Posted by HogPilot

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

Originally Posted by jimwhite

There it is...

Originally Posted by morphinapg

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

Originally Posted by morphinapg

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.

Originally Posted by morphinapg

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.

Originally Posted by morphinapg

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

Originally Posted by morphinapg

This subforum is about calibration,

Originally Posted by morphinapg

which is used to achieve better color on a TV.

Originally Posted by morphinapg

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.

Originally Posted by HogPilot

Everyone just needs to leave this thread be....

Originally Posted by dlarsen

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

Dave

Originally Posted by morphinapg

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.

Originally Posted by morphinapg

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

Originally Posted by GeorgeAB

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"

Originally Posted by morphinapg


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.