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Calibrated LED TV is too bright and washed out

kp278

Active Member
I spent a couple of hours calibrating my new TV last night, it's a Panasonic 42ET5B.
I'm using an i1d2 and colourHCFR, with the AVSHD709 test disc (windows).
This is what I did...
  • Turned all the extra settings off;
  • Set the picture modes to Cinema and Warm
  • Set the contrast on the 100% white to around 35ftL;
  • Set the brightness using basic reference test 1 (the image with the flashing black bars and reference black at 16 or 17);
  • Adjusted greyscale at 80 and 30 with white balance.
But when I ran the greyscale measure my graphs were awful. I tried again but still no where near where they needed to be, despite most of the x and y readings being 0.313 and 0.329 +/- upto 0.003 (IRE 0-20% still a bit off).

So I adjusted the gamma in the tv menu from 2.2 to 1.8 and ran greyscale measurement again. The results were pretty good (the averages at least).

But, the picture is very bright and washed out. I was in a dark room, so I'm wondering if just need to turn CATS on (at work at the moment). I don't really understand how I can get good greyscale readings but have such a bad picture?

1greyscale.JPG

2luminance.JPG

3gamma.JPG

4rgb.JPG

56500k.JPG
 

KelvinS1965

Distinguished Member
I haven't used HFCR for a long time (I bought Chromapure when it came out and got a free upgrade to 'Pro'), but I can see that your gamma is completely out of wack (technical term). IMHO getting gamma right is more important than getting greyscale right regarding how the picture looks: You may not notice a slight colour temp shift as your eyes tend to compensate anyway, but having the gamma wrong or 'bumpy' can be more obvious (IMHO) and spoil the image. FYI your gamma curve will tend to cause the following:

Too low at low IREs will tend to exagerate shadow detail (I actually do this on purpose but only to about 2.1 gamma for 5, 10 and 15 IRE on my projector). The sudden increase to 2.3/2.4 for 30 IRE to 70 IRE would tend to make the image too dark in the midtones (though the opposite of what you said in that it looks washed out in general :confused:). There is something very odd happening at 80 IRE and above, which could be indicating clipping, but you don't seem to be 'running out' of a colour in your RGB chart (I would expect to see one colour dropping off above 90 IRE if this was the case). Perhaps there is some 'contrast enhancement' type setting left on in an advanced menu?

What I would suggest is that you DON'T use the contrast control to set the fL, which is a hamfisted method (IMHO) to adjust the peak fL: This is what the backlight control is for. Use the flashing white bars in to see clipping for 235 or 255 (whichever you prefer, my choice is to clip above 235, but opinions vary on this). Then use the backlight to adjust a 100 IRE pattern to achieve your required fL. Bare in mind that 35fL may be too bright for a darkened room depending on your taste, decor and eyes. It is not 'the law'. ;) If you prefer 28fL or whatever, then use that. Or setup two presets for day and night time viewing.

Whatever you do, you should set the backlight first and then calibrate the greyscale and gamma as the backlight setting may effect the greyscale. I would also recommend not using the 1.8 gamma setting as that would usually give a washed out image compared to 2.2/2.3 (if they both were flat responses all else being equal).

Hope this helps, but don't get too wrapped up in the figures and don't forget to watch your TV as test patterns are pretty boring after a while. ;):D
 
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kp278

Active Member
Thanks for detailed reply, I don't have a back light control, although I've heard there's one in the service menu, just need to find out how to get in there
 

KelvinS1965

Distinguished Member
That's odd...I understand Plasma screens not having this control but usually LCD/LED TVs have this (all mine do, but they are Sony TVs of various ages 1-5 years 32"-40"). Perhaps it is controlled by which mode you use: Cinema would perhaps be a lower back light setting than Vivid (or whatever), but may also change other settings such as colour temp. I'm not familiar with Panasonic TVs sorry.

Actually I vaguely recall reading something about Panasonic TVs not having a proper contrast control so that may be the backlight. You can test this by adjusting the contrast control with the AVS HD709 basic patterns flashing white bars test pattern: If you adjust the contrast and the white bars start to clip (or lower it and more bars appear) then it is a traditional contrast (ie white clipping) control. If the bars stay the same but the picture brightness goes up or down, then it is the backlight. The only way to control the white clipping then would be to reduce the high end RGB controls together.
 

KelvinS1965

Distinguished Member
Apart from trying different modes, perhaps the CATS function you mentioned is the only way of adjusting the backlight, but I imagine it's like the 'light sensor' function on my Sony TVs. It will turn up the BL full in bright sunshine (in my conservatory, in previous years when we actually had a summer :rolleyes:) and then in the evening it lows the BL to minimum. This will effect the greyscale to some degree as the BL colour may shift slightly at higher power, but IMHO it's not the end of the world and at least you can see the screen.

Try turning the CATS on and off while measuring the fL on a 100 IRE pattern in a darkened room to get a feel for what it does. Maybe measure the greyscale and gamma with it off then on to see if it effects anything else. Then I'd recommend taking some baseline measurements in the different modes to see if you can get a flatter gamma response. Then see if the greyscale can be brought to 6500K without messing the gamma up. Otherwise it's a question of choosing the best compromise. FWIW I found my i1D2 wasn't very accurate when I compared it to a new (rented) i1Pro so I'd focus on the gamma, which the i1D2 was accurate at measuring and just aim for a flat greyscale even if it doesn't quite measure 6500K.
 
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kp278

Active Member
I went for True Cinema instead of Cinema and it's flattened out the graphs which is more like what I'm use to seeing. It also opened up a CMS rather than just normal/cool/warm so thats a bonus. I've attached the .chc file from HCFR- If you can't read it i'll get some screenshots up.

I spent a couple of hours calibrating but needs another couple of rounds. Blue is a little below the scale which is the obvious adjustment.
 

KelvinS1965

Distinguished Member
I don't have HFCR installed on my laptop anymore, but just to say that I found HFCR quite poor for gamut work. I'd be wary of making more than very small CMS adjustments using HFCR and an i1D2 (which itself isn't very good for gamut work). HFCR only shows 2D colour gamut results not the 3D ones so you miss out an important element of the colour gamut. You could again end up with a pretty looking chart, but a poor picture quality...

To explain: The warm/cool/whatever setting is for the greyscale colour temp and the CMS should control the six points on the gamut for Red Green Blue Cyan Yellow and Magenta (ie the primaries and secondaries). Typically you would adjust the CMS after you have a flat greyscale and gamma response calibration (then recheck the greyscale and gamma after adjusting the CMS incase of interaction).

Don't make too much adjustment on Blue in the CMS as a) The sensor isn't very accurate with blue anyway b) The eye is less sensitive to blue colour gamut being off a bit.

At least is sounds like you've found a solution to the original question.
 

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