Calibration Learning Experience

[ronnie 1.8]

This is more of an observation "light-bulb" moment I wanted to share on the forum. I've had my Panasonic 50" 8UK plasma for just over a year, and recently had it ISF recalibrated (the first cal being upon purchase) via a Denon DVD2910 (component). The picture was amazing. I recently upgraded my player to a Denon DVD3930CI, and the picture, via both HDMI and component, has PQ waaaay below the 2910. What I learned is that a calibration is between 2 components - the monitor/display and the source. I had a perfectly balanced PQ between a monitor and source, and even though the source is the same brand (Denon), that balance is broken. I now need my plasma recal'd to the new source.

 

[agarwalro]

I thought when getting a display ISF calibrated, the source is not used. Meaning, the tech will bring his own devices that will allow him to calibrate the input. This way you can change the source and know that your display is still good.

Am I missing something here?

 

[ronnie 1.8]

I thought when getting a display ISF calibrated, the source is not used. Meaning, the tech will bring his own devices that will allow him to calibrate the input. This way you can change the source and know that your display is still good.

Am I missing something here?

I know the ISF tech will try to get the display as accurate as possible "on it's own", and will only introduce the variables allowed by the DVD player (in my case) as necessary. The installer that did my system must have significantly modified the Denon DVD2910 settings, as when I replaced it with the Denon DVD3930CI, the PQ took a big drop. So bad, I cannot stand to watch it. I've made arrangements to have my plasma recal'd to my 3930 Mon 12/11, and I'm swapping players back to the 2910 until then. One, so that I can enjoy high quality DVDs again, and 2, so that he can see the A/B difference himself. In practice, I do not understand how a display can be calibrated without a source being used. A display is to do just that, display a source. And if that source pushes reds, or has way too high contrast, or low black levels, how can this not be reflected in the display? Taking this further, if the display were connected to 5 DVD players, I would expect the same disc and the same interconnects to produce 5 different images.

 

[ronnie 1.8]

I thought when getting a display ISF calibrated, the source is not used. Meaning, the tech will bring his own devices that will allow him to calibrate the input.

Yes, he brings his own equipment, but uses your DVD player to play his reference disc.

 

[100r1]

When you swaped the DVD players, Did you use the exact same cables & pluged into the exact same in-puts on the TV ?

if you did not use the same In-puts on the TV, you may need to set the settings (contrast, color etc.) the same for both in-puts on you TV. Many TV's have adjustable settings for each in-put on the set-up screen, and other TV's there are no adjustable differences between multiple in-puts of the same kind (Component, composite, S-Video, HDMI).

 

[ronnie 1.8]

When you swaped the DVD players, Did you use the exact same cables & pluged into the exact same in-puts on the TV ?

Yup, I did. I swapped players and AC power cords. I'm using the same component out cables, and of course the the same comp out on my AVR3805 is being used to the same input (3) on my plasma. I did also buy and install an HDMI board and HDMI cable. Though the PQ is significantly different in HDMI vs comp, they are both completely unaccptable compared to the calibrated 2910.

Looking on page 32 of the 3930CI manual, you see it has settings for contrast, brightness, sharpness (high and med range), hue, white level, black level, chroma level, enhancer, mpeg noise reduction, setup level, and others. The 2910 has similar settings. It's easy to see how changing these settings, but keeping the display the same, will produce a different picture.

 

[agarwalro]

but uses your DVD player to play his reference disc.

But that seems a bit illogical since I have the Samsung 841, known to have bad video levels. If this player is used to calibrate my TV, my TV is not truly calibrated. Rather it is the TV + DVD player combination that is somewhat accurate.

IMHO, using the DVD player is a temporary solution... two wrongs making one right, since the TV is made inaccurate to offset the DVD player's errors (assuming you dont have a reference quality DVD player... and most dont).This represents a gross error on the part of folks that dont have reference quality sources, since the minute they upgrade, their setup is no longer calibrated. Which is exactly what happened in your case.

IMHO, the TV should be calibrated to be accurate as a stand alone device, that way, if someone has a bad DVD player, they will be able to identify the device as being such, and upgrade it asap

 

[ronnie 1.8]

But that seems a bit illogical since I have the Samsung 841, known to have bad video levels. If this player is used to calibrate my TV, my TV is not truly calibrated. Rather it is the TV + DVD player combination that is somewhat accurate.

IMHO, using the DVD player is a temporary solution... two wrongs making one right, since the TV is made inaccurate to offset the DVD player's errors (assuming you dont have a reference quality DVD player... and most dont).This represents a gross error on the part of folks that dont have reference quality sources, since the minute they upgrade, their setup is no longer calibrated. Which is exactly what happened in your case.

IMHO, the TV should be calibrated to be accurate as a stand alone device, that way, if someone has a bad DVD player, they will be able to identify the device as being such, and upgrade it asap

I could not agree with you more. You've said it all. A person should be able to upgrade, especially within the same family (Denon 2910 to Denon 3930), and enjoy, theoretically, a better picture. Certainly no worse! I would imagine the 2910 is not considered reference, so the display would need to be adjusted to offset the inherent errors of the 2910, right? And now, if the 3930 does not have those errors, and is more "accurate", then problems arise. So as long as the DVD player is not reference, two wrongs are being used to make one right. That's gotta happen all the time, all over the place. Otherwise, why do manufacturer's allow their DVD players to be adjusted?

 

[JackT]

Calibration traditionally means acheiving a correct response to a KNOWN input. Is there no way to provide a known calibration input to a TV set? It seems like that should not be very difficult, especially if the TV is DIGITAL.

What you are basically saying is that it is unknown what the DVD is doing to the calibration signal, so the calibrator is making the TV look "correct" when receiving this mystery signal. That seems a little half-assed to me.

 

[ronnie 1.8]

Calibration traditionally means acheiving a correct response to a KNOWN input. Is there no way to provide a known calibration input to a TV set? It seems like that should not be very difficult, especially if the TV is DIGITAL.

What you are basically saying is that it is unknown what the DVD is doing to the calibration signal, so the calibrator is making the TV look "correct" when receiving this mystery signal. That seems a little half-assed to me.

So let's then say that a calibrator provides a known input, and calibrates a given display. The display is 100% accurate to the proper industry definition (not sure what that is, but you know what I mean). The display is now properly calibrated to that known input. Now, you connect your DVD player, your cable box, your game platform, etc.. Do you expect them to all produce an accurate image? Will "red" on the PS3 = red from the DVD player = red from the cable box?

 

[JKL1960]

I was actually doing the training to become ISF certified (but had to leave the job for health reasons) and have performed a few calibrations.

We used a signal generator, some sensors and a laptop loaded with software. At no point did we use any other signals.

It was also disturbing to see customers turn up their noses at a properly calibrated display to a 'hot one' out of the box. Seems people's eyes are as easily fooled as their ears.

 

[JackT]

So let's then say that a calibrator provides a known input, and calibrates a given display. The display is 100% accurate to the proper industry definition (not sure what that is, but you know what I mean). The display is now properly calibrated to that known input. Now, you connect your DVD player, your cable box, your game platform, etc.. Do you expect them to all produce an accurate image? Will "red" on the PS3 = red from the DVD player = red from the cable box?

You could only expect the various sources to produce properly calibrated images if they were properly calibrated. Fortunately, if your display is calibrated, those sources can now be calibrated to the display.

Here's a sort of related question: how do you calibrate television broadcast sources like a set-top box? Do they have adjustments? Are there calibration channels? Just wondering.

Interesting topic!

 

[JackT]

I was actually doing the training to become ISF certified (but had to leave the job for health reasons) and have performed a few calibrations.

We used a signal generator, some sensors and a laptop loaded with software. At no point did we use any other signals.

It was also disturbing to see customers turn up their noses at a properly calibrated display to a 'hot one' out of the box. Seems people's eyes are as easily fooled as their ears.

Interesting. That conforms to my expectation of a calibration procedure. The sensors are presumably optical sensors that measure color?

 

[agarwalro]

We used a signal generator, some sensors and a laptop loaded with software. At no point did we use any other signals.

Yes, that is what I would expect if I decided to get my TV calibrated. I am glad my expectations are in allignment with what seems to be the correctly instructed method of calibration. I imagine the tech's that use the DVD players either dont have the signal generator or are too lazy to spend the time using it... specially since reference images from DVE and Avia on the DVD player have the same effect, albeit not always accurate depending on the players errors.

Fortunately, if your display is calibrated, those sources can now be calibrated to the display.

I think that is the only way to do it and ensure that all your devices are performing at optimal level.

how do you calibrate television broadcast sources like a set-top box? Do they have adjustments? Are there calibration channels?

Probably via service menus.

 

[ronnie 1.8]

You could only expect the various sources to produce properly calibrated images if they were properly calibrated. Fortunately, if your display is calibrated, those sources can now be calibrated to the display.

That makes sense. So my calibrator, once ensuring my plasma was properly calibrated, then calibrated the DVD2910. Once I replaced it with a DVD3930, the total picture chain is no longer calibrated. Now the 3930 needs calibration.

 

[ronnie 1.8]

Yes, that is what I would expect if I decided to get my TV calibrated. I am glad my expectations are in allignment with what seems to be the correctly instructed method of calibration. I imagine the tech's that use the DVD players either dont have the signal generator or are too lazy to spend the time using it... specially since reference images from DVE and Avia on the DVD player have the same effect, albeit not always accurate depending on the players errors.

I think we're talking about the same thing. If a display is calibrated via a signal generator, some sensors and a laptop loaded with software, this does not apply to how a display is used. So calibrating a display in this manner gives one a properly calibrated display. Then what? We don't watch our displays, we watch a source viewed through the display. So now, the tech must do what? He/she must tweak the source to give the best picture possible. I don't think this is "lazy". You can have your properly calibrated display using only signal generators, but will enjoy an accurate picture only if the source is already accurate. And like someone already said, how many are? In my case, I am certain the tech calibrated my plasma, then put a disc in my DVD2910 and made adjustments to it. Now, with my DVD3930 in place, adjustments need to be made to it, but not to my plasma. This is not lazy, just the necessary process (calibrate the plasma, then make necessary adjustments to the source).

 

[JKL1960]

Interesting. That conforms to my expectation of a calibration procedure. The sensors are presumably optical sensors that measure color?

Yes they are. (One type for TV and another for projection.)

I don't recall any information about calibrating playback devices only display devices. So I'm not sure about that. I have been in the service grid for my Motorola HD cable box and don't recall any colour setting or adjustments being available.

I would be tempted to call Denon and see what they have to say. Ask them directly about calibrating their playback devices.

 

[JackT]

I think we're talking about the same thing. If a display is calibrated via a signal generator, some sensors and a laptop loaded with software, this does not apply to how a display is used. So calibrating a display in this manner gives one a properly calibrated display. Then what? We don't watch our displays, we watch a source viewed through the display. So now, the tech must do what? He/she must tweak the source to give the best picture possible. I don't think this is "lazy". You can have your properly calibrated display using only signal generators, but will enjoy an accurate picture only if the source is already accurate. And like someone already said, how many are? In my case, I am certain the tech calibrated my plasma, then put a disc in my DVD2910 and made adjustments to it. Now, with my DVD3930 in place, adjustments need to be made to it, but not to my plasma. This is not lazy, just the necessary process (calibrate the plasma, then make necessary adjustments to the source).

No, you really have to have something that is calibrated to an absolute standard. Especially in the case of a digital display, where basically you're feeding the diplay numbers. A given number is meant to produce a particular output.

The problem with calibrating the aggregate system is that you are hoping for miscalibrations to cancel out resulting in a calibrated result. This may not always be possible, and it seems you are just asking for trouble. If one or the other is miscalibrated enough, you may not be able to get back into a calibrated position.

Also, if you have more than one source, you will have to calibrate those other sources individually ANYWAY, so you really aren't gaining anything by calibrating your display to a particular uncalibrated source.

 

[ronnie 1.8]

No, you really have to have something that is calibrated to an absolute standard. Especially in the case of a digital display, where basically you're feeding the diplay numbers. A given number is meant to produce a particular output.

The problem with calibrating the aggregate system is that you are hoping for miscalibrations to cancel out resulting in a calibrated result. This may not always be possible, and it seems you are just asking for trouble. If one or the other is miscalibrated enough, you may not be able to get back into a calibrated position.

Also, if you have more than one source, you will have to calibrate those other sources individually ANYWAY, so you really aren't gaining anything by calibrating your display to a particular uncalibrated source.

I agree with this completely. So if a tech does calibrate a display to an absolute standard, and then tests the image from a particular source, a DVD player, is't it then possible that tech may need to adjust the DVD player's settings to produce said absolute standard? I think this is what happened with me, though I cannot reach the tech to confirm. Or are you saying that, no matter what the DVD's settings are, the plasma calibrated to an absolute standard should continue to produce an absolute standard image? I have to believe the source's settings would effect the display.

 

[JKL1960]

I agree with this completely. So if a tech does calibrate a display to an absolute standard, and then tests the image from a particular source, a DVD player, is't it then possible that tech may need to adjust the DVD player's settings to produce said absolute standard? I think this is what happened with me, though I cannot reach the tech to confirm. Or are you saying that, no matter what the DVD's settings are, the plasma calibrated to an absolute standard should continue to produce an absolute standard image? I have to beleive the source's settings would effect what the plasma displays.

You are right that the source can effect the image quality, so could a loose wire. If your DVD player was hooked up via component cables and one of them was poor it could effect your picture. This is why I would think that you must use a signal generator to calibrate to eliminate these scenarios.

I am curious about calibrating playback devices and I am going to do a little research.