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LG White Balance Pre-Calibration using Service Menu

 
Author ConnecTED
DPS
#1 | Posted: 13 Aug 2020 21:10 
The info about why doing Service Menu White Balance provides a better picture from regular TV menu adjustments is available to that page.

The White Balance in Service Menu has three presets for White balance (Cool - Medium - Warm).

In contrast, the TV regular OSD menu has six color temp selections.

During the LG factory Quality Control process, they will calibrate the White Balance of the panel using an LG software.

It's an automatic calibration procedure since LG software communicates with the TV. It will apply the adjustments based on the readings it will take.

The software will display an 80 IRE full-field pattern and will perform the panel calibration.

These adjustments are directly affecting the panel to count for pane-per-panel variations, before the calibration controls of the regular TV menu.

LG has defined specific coordinates for each color temperature, to make it simple, 6500K for 'Warm', 9300K for 'Medium' and 11000K for 'Cool'.

White Balance settings of 'Warm' in Service Menu will affect the 'Warm 1, Warm 2, and Warm 3' preset of regular TV Menu.

White Balance settings of 'Medium' in Service Menu will affect the 'Medium and Warm 1' preset of Normal TV Menu.

White Balance settings of 'Cool' in Service Menu will affect the 'Cool' preset of Normal TV Menu.

For SM WB, I recommend the users to use:

SM Cool for pre-calibrating the 109% White for SDR (with SDR pattern) and select Cool in the regular TV menu.

SM Warm for pre-calibrating for 100% White (with HDR pattern) and select Warm 2 on the regular TV menu.

We don't want the adjustments of color temp preset to affect a different color temp calibration.



For White Balance calibration using Service Menu, there is a setting 'Test Pattern' with '100IRE', '80IRE' and 'OFF' as options.

The 'IRE' selections will display an internal generated full-field pattern.

These patterns will bypass a lot of signal processing steps.

We don't want this to happen; for that reason, select 'OFF' and use a 109% SDR White pattern with 11% window size generated from your HDMI input from my calibration disk you are using, for example.

When the RGB Gain has values of 192.192.192, it will provide the panel's maximum dynamic range. (RGB Cut 64.64.64 are the default values)

LG in the factory, but users also have to keep the Red Gain @ 192 (to keep max dynamic range) and then reduce only values from G Gain and B Gain to calibrate the RGB balance.



Note: don't press the RESET button to the White Balance menu in Service Menu.

After the WB calibration during factory pre-calibration, the system will send an OK value that the WB calibration has performed.

LG's QC technician will see that White Balance has performed when he looks at the initial service menu screen. See the left side of the following picture where it says ''Adjust White Balance: OK'':



When the user presses 'RESET' to the SM WB menu, it will delete the calibration values stored from the factory for his panel.

A warning with red letters (right side of the picture) will appear, which will say ''Adjust White Balance: NG'' (aka NOT GOOD).

Looking at the left side of the picture, its how the TV should look when someone hasn't pressed 'RESET', after performing manual cal of SM WB (or before any manual SM WB adjustment).

LG is still incorrectly naming the RGB Balance controls as 'IRE', a term which means the ''voltage of the signal in the analog world'', as used in CRT's before 20 years.

TVs, in digital world signaling, have to use '%' or 'code values' for grayscale steps, nor IRE.

When you perform 'basic' pre-calibration from the SM WB menu, it will require fewer adjustments from regular 'multi-point' TV menus later.

While the picture will look better, the required time for the calibration will be shorter.

The regular TV menu has many calibration controls and settings.

When you change all these controls, an LG processing unit with combine all your setting values to and it will calculate a global correction for the TV.

SM Panel calibration + global correction of regular TV Menus will manipulate the signal before it enters the RGB-> WRGB processing unit -> Panel.

LG's controls for manual cal can add artifacts or degrade pictures (even with Luminance controls in RGB Balance) because the algorithm is very complicated.

The additional processing can bring some out-of-valid-range adjustments and can affect the picture.

It's the reason we suggest to users to not use Luminance controls in 20-Point RGB-Balance controls and CMS to some sets.

The problems will appear with real movie evaluation, or when the users will perform an evaluation using static color ramps or gradation patterns of my calibration disk.

The two-color reproduction ramps are useful for quick evaluation.

So after a lot of testing, doing Service Menu White Balance is the best method to pre-calibrate the display before the profiling or before starting a manual calibration using the available calibration controls from the regular TV menu.

It will provide a cleaner picture with smoother gradations.

After the SM WB calibration, the users can continue with multi-point RGB balance calibration from the regular TV menu (skipping the 2-Point RGB balance of regular TV menu).

When you are not calibrating SM WB and using a 2-Point RGB balance of regular menu (or multi-point), this can make the internal processing algorithm more complex.

For example, the SM WB can remove Green while your regular TV menu to add Green.

Two settings which perform similar kind of adjustment have different values, and this fact will add complexity and unnecessary additional processing to the signal manipulator.

The side-effects can be noticed during the evaluation of gradation.

It's a better solution to use a 2-Point RGB balance from one White Balance menu and not apply the same adjustments from both menus (regular TV menu + SM) simultaneously.

Author Johnbar
ZRO
#2 | Posted: 16 Aug 2020 21:19 
Great info as always Ted. Thank you for taking the time to compile and post this information.

Author JR84
ZRO
#3 | Posted: 19 Aug 2020 23:23 
Hi Ted. If I have pushed the reset button what data would I have deleted exactly? Has it removed the factory calibration data?

Can this be fixed?

Author ConnecTED
DPS
#4 | Posted: 20 Aug 2020 13:38 
When you press reset, it will clear the custom White Balance factory values from the SM WB menu.

Then, it will have 192.192.192 @ RGB-High and 64.64.64 @ RGB-Low.

I have described to the instructions above that it will appear an NG red text to the SM menu as a flag, when you press 'RESET'.

When you calibrate your White balance with your meter, you will improve the factory (basic) calibration.

Just the NG flag can't be restored to the standard 'gray' color, but it's not affecting the TV performance.

However, users should not press RESET.

Author JR84
ZRO
#5 | Posted: 20 Aug 2020 14:36 
I have pressed reset previously and the values returned to 192.157.125 RGB- High and 64.64.64 RGB- Low.

I'm not suggesting people should be pressing reset, I just wanted to know if I had lost any factory calibration data.

Author ConnecTED
DPS
#6 | Posted: 20 Aug 2020 16:48 
Do you see NG?

Author JR84
ZRO
#7 | Posted: 20 Aug 2020 23:09 
I have a CX and the service menu looks different to that.

Author ConnecTED
DPS
#8 | Posted: 20 Aug 2020 23:49 | Edited by: ConnecTED 
Check IN-START menu.

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 LG White Balance Pre-Calibration using Service Menu

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