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Trouble with high-end Gamma on PN58B650

post #1 of 13
7/22/12 at 7:06pm
Thread Starter 
Hello,

I have recently calibrated my PN58B650, using an i1Display Pro and ChromaPure.

The grayscale looks great, the color gamut chart looks great. The high-end gamma drops off pretty severely.

I have tried dropping the RGB gain together, but this just seems to lower the overall contrast and total output.

What can I do to fix the gamma on the high-end?

Attached is the detailed report from ChromaPure.

Settings:

Picture Mode: Movie
Picture Temp: Warm 2
Contrast: 95
Brightness: 54
Color: 50
Hue: 50/50
Sharpness: 3
Backlight: 10
Red Gain: 28
Green Gain: 25
Blue Gain: 31
Red Offset: 24
Green Offset: 25
Blue Offset: 24
Gamma: -1

CMS:
Red: 52, 4, 2
Green: 0, 48, 0
Blue: 3, 0, 51
Yellow: 49, 50, 0
Cyan: 0, 48, 48
Magenta: 51, 3, 48


CalibrationSummaryDetailed-Samsung-PN58B650.pdf 2437k .pdf file
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post #2 of 13
7/23/12 at 9:07am
What size and type of measurement windows are you using? I just checked some of my past B650 reports and none of them show a significant gamma drop at the high end, and your settings don't look unreasonable. So I would suspect either the widow size/type or check to make sure if you're running the video through a receiver that it is neutral.
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post #3 of 13
7/23/12 at 9:14am
Try lowering your contrast and/or backlight to see if that will help.

I own a PN50B450 and this technique works for me.
Edited by vincentfam - 7/23/12 at 9:22am
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post #4 of 13
7/23/12 at 9:21am
Thread Starter 
Quote:
Originally Posted by Chad B View Post

What size and type of measurement windows are you using? I just checked some of my past B650 reports and none of them show a significant gamma drop at the high end, and your settings don't look unreasonable. So I would suspect either the widow size/type or check to make sure if you're running the video through a receiver that it is neutral.

I'm using the ChromaPure Windows test patterns for Gamma from the AVS Calibration disc.

I am running everything through a Denon AVR-2310.

Should I try calibrating the TV without the Denon?
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post #5 of 13
7/23/12 at 9:23am
Thread Starter 
Quote:
Originally Posted by vincentfam View Post

Try lowering your contrast and/or backlight to see if that will help.

I will try that, but I'm already only getting about 29.5 Fl, with my current settings. I guess I will have to make a choice about gamma vs. overall image output.
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post #6 of 13
7/23/12 at 9:27am
Alternative method: Keep the contrast/backlight the same, and try lowering your gains (which should raise high end gamma).
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post #7 of 13
7/23/12 at 9:35am
Thread Starter 
Quote:
Originally Posted by vincentfam View Post

Alternative method: Keep the contrast/backlight the same, and try lowering your gains (which should raise high end gamma).

I actually did try the "ganging" method of lowering the RGB gains together. All it did was drop the contrast and the total light output. Functionally, it seemed to be identical to lowering the contrast.
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post #8 of 13
7/23/12 at 9:44am
Quote:
Originally Posted by tbell_oc View Post

I actually did try the "ganging" method of lowering the RGB gains together. All it did was drop the contrast and the total light output. Functionally, it seemed to be identical to lowering the contrast.

that's because it is
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post #9 of 13
7/23/12 at 9:44am
Quote:
Originally Posted by tbell_oc View Post

I'm using the ChromaPure Windows test patterns for Gamma from the AVS Calibration disc.
I am running everything through a Denon AVR-2310.
Should I try calibrating the TV without the Denon?

try the APL small windows
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post #10 of 13
7/23/12 at 10:28am
I use the apl small windows as well, in part because of PlasmaPZ80U's recommendation and in part because I cannot download the new gamut calibration disk (in this forum) which has better patterns to use for plasma tvs.
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post #11 of 13
7/23/12 at 12:22pm
Thread Starter 
I'll give the small APL windows a try and report back. Thanks for the suggestions everyone.
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post #12 of 13
7/23/12 at 12:47pm
Here is the link to the recommendations for patterns: http://www.avsforum.com/t/1420057/what-pattern-for-what-display-type

This link is recommending 10% windows 22%apl patterns for plasma tvs, which is included in the gamut calibration disk.
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post #13 of 13
7/26/12 at 4:15pm
Thread Starter 
Thanks everyone. I sacrificed a bit of brightness and used the patterns from the Gamut Calibration Disc to get a substantially better Gamma curve.

Here's the final report.
PN58B650-20120725.pdf 2422k .pdf file
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