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Discoloured grayscale

post #1 of 18
Thread Starter 
I cannot seem to correct my discoloured grayscale on my UK VT30 Panasonic.
I tend to experiences green and magenta hints in some of the upper levels, even though Calman is telling me different. I have tried many time to correct this with different pattern types and contrast settings, but still seem to experience this. It is also present whilst watching some blu rays, Batman Dark Knight where there are bright scenes that fade. Other examples are edges to clouds. It can be anywhere on the display.

Any ideas as to what maybe causing this?
Edited by ndaa75 - 5/19/13 at 4:02am
post #2 of 18
Quote:
Originally Posted by ndaa75 View Post

I cannot seem to correct my discoloured grayscale on my UK VT30 Panasonic.
I tend to experiences green and magenta hints in some of the upper levels, even though Calman is telling me different. I have tried many time to correct this with different pattern types and contrast settings, but still seem to experience this. It is also present whilst watching some blu rays, Batman Dark Knight where there are bright scenes that fade. Other examples are edges to clouds. It can be anywhere on the display.

Any ideas as to what maybe causing this?

are you using any 10-pt white balance controls? or just 2-pt? (it's possible there are visible errors between the data points your are measuring... check a grayscale ramp and steps and try measuring 20-pts)

also, try 2-pt grayscale only if you are currently using 10-pt
post #3 of 18
also, it's possible the APL you're calibrating for and the APL you're noticing this discoloration with is different (since some displays vary both color and luminance as the APL changes)
post #4 of 18
Thread Starter 
Quote:
Originally Posted by PlasmaPZ80U View Post

are you using any 10-pt white balance controls? or just 2-pt? (it's possible there are visible errors between the data points your are measuring... check a grayscale ramp and steps and try measuring 20-pts)

also, try 2-pt grayscale only if you are currently using 10-pt

Yep, using and have used both 2pt and 10pt. Full screen grayscale steps show high green at 75 and pink a 85 stim. Have used both levels as high wb correction in 2pt however this does not erradicate the issue in movies!
post #5 of 18
Thread Starter 
Quote:
Originally Posted by PlasmaPZ80U View Post

also, it's possible the APL you're calibrating for and the APL you're noticing this discoloration with is different (since some displays vary both color and luminance as the APL changes)

Yep, thought that too however i have adjusted the 10pt while freezing a movie to see if it has any impact, alas it dd not.
post #6 of 18
is there an option that lets you turn off the 10-pt controls altogether (like on the Samsungs)?

also, try my earlier suggestion of measuring more datapoints


can you tell me whether you see this discoloration on a continuous grayscale ramp and if so, what does it look like?
post #7 of 18
Thread Starter 
Ill post some pics a little later
post #8 of 18
Recently I just happened by chance to have access to a UK model and got to try out autocal. I found nice graphs, but poor results with banding type effects in the upper reaches of the ramps.

I see this also in manual calibration if you adjust controls to extremes between 10% increments. With that in mind check the values of the white balance and gamma around the troublesome areas and you might find full range adjustments here especially look for adjustments in opposite directions. I suspect the culprit is the interface between two points made worse by non linear gamma tracking in plasma designs requiring large 10% step adjustments.

I'll steal Mr Kanes words here, "Extreme caution must be exercised" when making large adjustments with detailed controls.

Sometimes you have to choose the lesser visual effective error over graphical exactness.
post #9 of 18
Quote:
Originally Posted by ndaa75 View Post

I cannot seem to correct my discoloured grayscale on my UK VT30 Panasonic.
I tend to experiences green and magenta hints in some of the upper levels, even though Calman is telling me different. I have tried many time to correct this with different pattern types and contrast settings, but still seem to experience this. It is also present whilst watching some blu rays, Batman Dark Knight where there are bright scenes that fade. Other examples are edges to clouds. It can be anywhere on the display.

Any ideas as to what maybe causing this?

Did you check uniformity of screen? My TX-P50VT30E have some green blobs on screen which you can see in some specific scenes. May be this is your case too? The easiest way to spot them- to use 10% full grey screen pattern. Also be carefull with gama controls during callibration, In VT30 they are not on the same level (implemetation) as in new models (50/60 series). I just calibrated TX-P50GT60E and all WB and gama controls works nicely (properly). My VT30 in comparison to GT60 is like nightmare from point of callibration frown.gif.

P.s. I would like to thank you a lot for your Callibration disk for Calman!!!
post #10 of 18
Thread Starter 
Quote:
Originally Posted by IcetomLT View Post

Did you check uniformity of screen? My TX-P50VT30E have some green blobs on screen which you can see in some specific scenes. May be this is your case too? The easiest way to spot them- to use 10% full grey screen pattern. Also be carefull with gama controls during callibration, In VT30 they are not on the same level (implemetation) as in new models (50/60 series). I just calibrated TX-P50GT60E and all WB and gama controls works nicely (properly). My VT30 in comparison to GT60 is like nightmare from point of callibration frown.gif.

P.s. I would like to thank you a lot for your Callibration disk for Calman!!!

No green blobs, this is completely random and dependent on whats on screen regardless of position.

I have tried all settings - calibrated, no calibrated, THX, photo, cinema, makes no difference - im beginning to thinks it the nature of this particular panel - there is nothing I can do to remove it.
In respect of the VT30, yes, calibration controls are as buggy as hell and low light in pro modes just makes no sense at all. Just adds horrid contouring.
Its a real shame Panasonic do no support firmware updates for this set any more as im sure these issues could have been overcome.

Glad you like the disc!
post #11 of 18
Regarding to APL patterns you may read article from Master Of All Calibrators here
post #12 of 18
Thread Starter 
Quote:
Originally Posted by prsut View Post

Regarding to APL patterns you may read article from Master Of All Calibrators here

Great article.
post #13 of 18
Quote:
Originally Posted by prsut View Post

Regarding to APL patterns you may read article from Master Of All Calibrators here

The other side of that is, if it's just as easy to use APL patterns, it certainly does no harm to use them. You could also take Michael's argument to the extreme and say, why not just run full field patterns on a plasma. But the main thrust of his article is quite accurate. In spite of all the hand wringing, APL's effect on grayscale calibration is subtle.
post #14 of 18
Greetings

We want to try to avoid a situation where we are simply cherry picking the results to give us a happy graph. Regardless of whether you can actually see a difference or if such an action resulted in some real tangible end result.

Remember ... one of the points here is to try it out for yourself and not take anyone's word based only on faith.

Regards
post #15 of 18
I have not seen anyone claiming that pattern size significantly affects grayscale dE on either pannys or samsungs, in fact Tom and I concluded just the opposite about a year ago. gamma has a more measurable variability but this is a matter of taste for the shifts we measured so yes, pick the ones that you like. There is however a theoretical argument to be made for staying within a range of APLs that represent typical movies (if movies are what you are most concerned with regarding maintaining stable gamma).
post #16 of 18
Thread Starter 
Quote:
Originally Posted by zoyd View Post

gamma has a more measurable variability but this is a matter of taste for the shifts we measured so yes, pick the ones that you like.

Gamma and plasmas. Mmmmmm. Ive learnt to set your target gamma with the dispay and then leave well alone unless there are any unusual spikes in your readings. It is only at this point do i adjust using the 10pt system to try and correct the anomaly in order to achieve a flatish line. Cant say i take much notice of the numbers, within reason.
post #17 of 18
obvious question if your eyes see different things than what the software reports (which reads data from your meter):

what meter are you using, and if it is a colorimeter, are you profiling to a spectro ?

- M
post #18 of 18
Thread Starter 
Quote:
Originally Posted by Iron Mike View Post

obvious question if your eyes see different things than what the software reports (which reads data from your meter):

what meter are you using, and if it is a colorimeter, are you profiling to a spectro ?

- M

Yes meter i1d3 is profiled from my i1pro spectro.
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