grayscale calibrating

[D65]

hey all,

I was wondering if there is an experienced isf calibrator here, who could answer some of my questions. regarding greyscale adjustment.

I just took an isf course and began calibrating my 436 pioneer. but I can't seem to get the grayscale accurate. so my question is: what errors should I favor in the grayscale?, either high or low readings?. when I measure at 30 and 80 IRE, the middle of the scale drops to 6000 K and the low end is never right too.....but I was told that the lowest numbers can't be accurately measured anyway.

Maybe somebody with some experience can enlighten me?....

Thank you

Dimitri

[Piers]

The Pioneer 436 range usually calibrates well and you should be able to get close to D65 across the range. Calibrating the 30 IRE point is critical.

What equipment are you using?

[Neil Davidson]

Hi Dimmie,

What course were you on? Was it one of Tom's?

Cheers
Neil

[D65]

Originally Posted by Piers

The Pioneer 436 range usually calibrates well and you should be able to get close to D65 across the range. Calibrating the 30 IRE point is critical.

What equipment are you using?

Thanks for the reply, I'm using datacolor 6 with the spyder2.

I'm usually at 30 and 80. But I found out today that I can get an accurate grayscale when I put the color primaries and secundaries back in the middle position.....does that sound familiar?. It's not the way to go I know, but it could shed some light on the problem.

dimitri

p.s. I get a very dark picture after calibration also, the wizard in datacolor takes me all the way in the - area of the pioneer, in between -30 and -10 for all rgb levels.

[D65]

Originally Posted by ceenhad

Hi Dimmie,

What course were you on? Was it one of Tom's?

Cheers
Neil

Yes it was

dimitri

[Neil Davidson]

Hi Dimmie,

The xx6 models do not track the greyscale very well when you adjust the primaries. The best thing to do is leave the primaries at default and then correct the greyscale then adjust the secondaries only for best colour accuracy. The xx7 models do not show this behaviour and can be made to track an accurate greyscale whilst having almost perfect primaries and secondaries for SD or HD material.

I would repeat the calibration using the greyscale wizard rather than the calibration wizard as I always find this a little more flexible and less restrictive. All of the required instruments are available so you can check your accuracy against a number of different parameters.

ColorFacts 7.0 is released on Monday and an upgrade is available. It adds a couple of features you may find useful.

Cheers,

Neil

[Piers]

To put it bluntly if you adjust the primaries you totally screw up the grey scale - my ISF colleagues will no doubt comment.

[Gordon @ Convergent AV]

Hi guys,

Sorry, been on the road working. yes as has been noted. DO NOT ADJUST primaries on the 5th and 6th gen Pioneers. Is a waste of time. You can adjust secondaries though and achieve colour accuracy and greyscale. 7th gen have different colourspace settings that allow you to have it all and correct primaries.

Gordon

[D65]

thanks guys,

I'll do that, but when is a good time to stop adjusting the grayscale?. It seems that when I calibrate the grayscale and than go back to br./contr.
I have to turn the brightness way up to compensate for the grayscale adjustment, and when I go back to the grayscale it takes me further down in brightness. In the end I wind up with my low rgb levels in the lowest possible position and the brightness controll at +18?!?!?. That can't be right.

Should I maintain the rgb levels for high and low somewhere in the middle of the pioneer scale(around 0)? or should the highs be in the + range and the lows in the - ?. Or is there no preferred position?.

Thanks

dimitri

[Piers]

When you adjust the greyscale it has an impact on both white and black but in my experience it shouldn't be huge - one or two clicks to put it right.

I don't use ColorFacts here so cannot comment on your other questions.

[Gordon @ Convergent AV]

My top tip is to NOT adjust GREEN unless you really, really have to in the CTEMP settings. It has the largest affect on luminance and will mean you'll have to re-adjust brightness and possibly contrast..but not by the huge amount you are talking about. The other thing could be that you have power saving modes turned on that should ideally be off.

Gordon

[Mr.D]

Originally Posted by Gordon @ Convergent AV

My top tip is to NOT adjust GREEN unless you really, really have to in the CTEMP settings.

Gordon

Totally agree with Gordon on this . I only adjust green if I really have to. I also tend to drop levels rather than add them to reach my aims. If I've lost too much luminence I'll then bring them all up together. Some displays even have ganged "all cuts , all drives" controls for this very purpose. If you drop too much luminence the meters can start to get inaccurate at the low end

Although you will likely have to readjust to meet your target aims as the luminence increases , its never uniform.

This is also how you control your luminance aim for a given gamma at the low and high ends of the grayscale , although a lot of displays can be flakey in this regard. I generally just get the D.65 aims correct and then model the gamma and see if the luminance is badly off for a given target gamma at the relevant intensity reference points. Usually I'm close enough to the target gamma to not bother readjusting it. Rechecking black and white points and readjusting if necessary is usually sufficient.

[D65]

Thanks for the tips guys!

I'll take them all in consideration when I trie again!

Dimitri