Josh Bendavid

  • Sure I’ll have a look.

    aiopylgtv is not doing any level mapping itself aside from applying the offsets present in the cube file if present, according to the cube file format…[Read more]

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 2 months ago

    Is aiopylgtvcommand able to set the peak luminance values for HDR10 and DV on the 2019 models? I took a look at the source on github and found “set_tonemap_params” and “set_dolby_vision_config_data”. I’m just not sure what to do from here. Is it as simple as running the following if I wanted to change peak luminance to 750.0 and change nothing e…

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  • A few more details I’ve managed to work out for the image pipline (for the C8 and in SDR mode at least):

    With brightness and contrast at 50/100, a 10 bit input signal 0-1023 is mapped onto internal values of 0-4092, but with some clipping and not perfect alignment.    The  (33^3) 3D LUT maps an input of 0 onto the first entry, and an input of 40…[Read more]

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 8 months ago

    The 2.2 and 0.45 variables are not really LUTs but rather booleans that switch on and off two (opposite) gamma transformations.

    These correspond to the “De-gamma” and “Re-gamma” steps in the signal processing pipeline here:

    https://displaycalibrations.com/lg_2018_oled_profiling_using_lightspace.html

    Calman sets both of them to 0 (disabled) for…[Read more]

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 8 months ago

    Thanks for catching the typo (this issue was introduced recently as part of other changes unrelated to calibration)

    The valid picture mode strings are listed in the documentation, as well as a warning about ddc_reset (I’ll make it bigger :),  but indeed the mapping to the picture mode names in the TV UI is not written anywhere.  In fact it may d…[Read more]

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 8 months ago

    Ok I see your point, but for the moment I was intending to encourage users to call the library from a python script as in the documentation examples, rather than using the command line tool.  (The use of named function parameters is less error prone, and aiopylgtvcommand is not really a proper client, but just a thin interface to call functions…[Read more]

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 8 months ago

    The documentation is intended to live in the Readme.md on github.

    I was intending to write a full end to to end guide for using this with DisplayCal once I’m satisfied that I have a consistent procedure.

  • You can use the ddc_reset function in aiopylgtv to reset to a consistent state.  It has an additional boolean parameter reset_1d_lut to control whether the 1D LUT is reset or not.  Since the 2018 sets at least behave differently once the 1D LUT has been set/reset you may want to keep the factory 1D LUT, ie call ddc_reset(picMode, False)

    As soon a…[Read more]

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 9 months ago

    Ok, is that also true if I’m reading the .cal file directly to upload to the 1d lut in the TV?

  • Josh Bendavid replied to the topic LG C8 Lut in the forum General Discussion 9 months ago

    In order avoid DisplayCal and/or ArgyllCMS from messing further with the ranges, I needed to hack the code in DisplayCal, changing https://sourceforge.net/p/dispcalgui/code/6382/tree/trunk/DisplayCAL/madvr.py#l638 to always return (0., 255.) regardless of what level is actually set in madTPG.  (@fhoech is there a proper way of dealing with this,…

    [Read more]

  • I think I uploaded the LG C8 .ccss but I can’t find it in the database.

    And I just remembered I was wary about using a ccmx because it’s a WRGB panel, so the pure R,G,B readings (captured for the gamut mapping) will be drifted by including W in the ccmx calculation. CalMAN didn’t show me by how much but DisplayCAL gave me an idea (probably de~0.…

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  • I test this by setting the 1D lut to all white except for the first and last elements which are set to output black, and the 3D LUT to unity.  The first and last RGB values which produce black are then as follows:

    SDR Black Level Low Brightness 50 Contrast 85: 66-1014

    SDR Black Level Low Brightness 50 Contrast 84: 65-1017

    SDR Black Level Low…[Read more]

  • And with the rest of the attachments.

     

  • Hi,

    A few more technical things.

    1. In order for any of the calibration and profiling to work properly, there has to be a proper mapping from 0.0-1.0 values being sent by ArgyllCMS and the first and last entries of the LUTs on the TV.  In order to get the proper alignment of values, I found that the following combination of black level,…

    [Read more]

  • Ok, at least one mistake I was making with Profile Only was to use Absolute colorimetric rendering intent.  Using Absolute Colorimetric with white point scaling seems to do something much more sensible when the white point is not pre-calibrated.

  • One thing to be aware of.  One shoudl NOT run “profile only” unless the white point is correctly calibrated to start with.

    Ie, even if one wants to use only the 3d lut for the TV, then one should still run the calibration step in DisplayCal (but in this case check enable “Apply calibration” in the 3D lut settings.)  Doing things this way with t…[Read more]

  • Are you sure the dithering behaviour is not changing when resetting the 1d LUT ?

  • The 1D LUT can be created by running the calibration procedure (ie by having Tone Curve set to anything other than “as measured” in the Calibration tab in displaycal).  Then the .cal file created with the profile can be uploaded.  Or was the question something different?

  • My understanding of the behaviour is that the 3d lut does not affect the tv menu/GUI (and I think also the GUI in smart tv apps)

  • In DV mode, the DV chip shall be allowed to handle all the 3D color mapping (dynamic metadata based tone mapping and color space conversion), so any such processing should be bypassed in the TV’s processor. It looks like it was more convenient for LG to leave these steps (like the 3DLUT processing) in the chain and use (most probably) neutral f…

    [Read more]

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