srgb 2.4?

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  • #39662

    Erica
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    I use my LG C2 OLED TV for desktop use solely to do normal computer things and play video games. I don’t really watch movies. My understanding is srgb’s gamma is not same as “regular” 2.2 gamma because it’s flatter at the end of the curve for near blacks. So if I set it to display gamma 2.2 while the game was mastered to be displayed w/ srgb tone curve, near blacks will be too black. Calibrating for srgb solves this but my viewing conditions are pitch black.

    Also note that many color spaces are encoded with, and labelled as having a gamma of approximately 2.2 (ie. sRGB, REC 709, SMPTE 240M, Macintosh OS X 10.6), but are actually intended to be displayed on a display with a typical CRT gamma of 2.4 viewed in a darkened environment.
    This is because this 2.2 gamma is a source gamma encoding in bright viewing conditions such as a television studio, while typical display viewing conditions are quite dark by comparison, and a contrast expansion of (approx.) gamma 1.1 is desirable to make the images look as intended.

    So if you are displaying images encoded to the sRGB standard, or displaying video through the calibration, just setting the gamma curve to sRGB or REC 709 (respectively) is probably not what you want! What you probably want to do, is to set the gamma curve to about gamma 2.4, so that the contrast range is expanded appropriately, or alternatively use sRGB or REC 709 or a gamma of 2.2 but also specify the actual ambient viewing conditions via a light level in Lux, so that an appropriate contrast enhancement can be made during calibration. If your instrument is capable of measuring ambient light levels, then you can do so.

    Ok, higher gamma for pitch black room. But how do I increase gamma for srgb when it’s just srgb in the options? If I set gamma to 2.4 or BT1886, I run into same issues w/ setting gamma to 2.2 w/ end of the curve not being flattened like srgb and near blacks being too black.

    So correct answer is use srgb option but specific ambient lighting conditions of near 0 nits as measured by light sensor of my Calibrite Plus? Does anyone have experience w/ this setting, and does it do exactly what I think it’s supposed to do?

    Then I guess there’s the issue of whether the game was actually mastered to be viewed on srgb or bt1886 or some such. But what I think isn’t an issue is the ICC profile working as the game is borderless window. Because OLED has ” real black response “, I set Black Output Offset to 0%?

    • This topic was modified 4 months ago by Erica.
    • This topic was modified 4 months ago by Erica.
    #39665

    Erica
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    I can’t edit my post so I’m making a new one.

    Here is a post by Light Illusion about gamma for end users: 

    There is a misconception that the sRGB colour space standard has a compound gamma, with a linear portion close to black.
    This is incorrect, as this is the sRGB Encoding standard, not the target colour space standard for display calibration.
    For display calibration the target colour space should use a simple power law gamma, 2.2.

    …For display calibration it is incorrect to use these standards, and pure power law gamma should be used…

    So what should I, as a end user playing video games and doing random things on my computer in dark room, be using? sRGB w/ ambient light measurement reading of very low lux, or just BT1886, which is identical to “pure power law gamma” 2.4 given OLED display? I am so confused. :^)

    #39697

    NoVoicemail
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    Lg oleds crushes black from the factory, its an issue inherent in wrgb oled technology, samsung rgb oleds dont have it as bad. For LG just set to gamma 2.2 and run profiling with 256 neutral patches as recommended here:

    https://github.com/dantmnf/MHC2#recommendations-for-creating-device-icc-profiles

    “To achieve optimal results, consider creating a custom testchart in DisplayCAL with a high number of neutral (grayscale) patches, such as 256”

    this is the easiest thing you can try. for more advance LG calibration check the LG C8 lut thread and bscpylgtv tool.

    #39707

    Erica
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    Lg oleds crushes black from the factory, its an issue inherent in wrgb oled technology, samsung rgb oleds dont have it as bad. For LG just set to gamma 2.2 and run profiling with 256 neutral patches as recommended here:

    https://github.com/dantmnf/MHC2#recommendations-for-creating-device-icc-profiles

    “To achieve optimal results, consider creating a custom testchart in DisplayCAL with a high number of neutral (grayscale) patches, such as 256”

    this is the easiest thing you can try. for more advance LG calibration check the LG C8 lut thread and bscpylgtv tool.

    How does it crush blacks if in greyscale testing it passed with low delta E? (Calibration profile verification)

    • This reply was modified 4 months ago by Erica.
    #39709

    NoVoicemail
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    check out this oled calibration guide written by flanders scentific, on page 7 it states
    https://www.flandersscientific.com/calibration/CalMAN/FSI-CR100-CalMAN-Resolve.pdf

    OLED Black Level Setup and BT.1886 Calibration
    The default black level of OLED monitors is effectively 0 nits (cd/m2), which is well below the accurate
    or repeatable thresholds of most measuring devices. A BT.1886 EOTF on a display with a black level of
    0 nits is actually equal to a 2.4 gamma response. For both of these reasons it is advisable to calibrate to
    a target of 2.4 gamma when calibrating an OLED with black at 0 nits so that noise or junk readings are
    not being factored into your calibration’s EOTF. Once calibration is complete you can use the “bright”
    knob/key on the monitor to adjust your black level higher if desired. When calibrated to a target of 2.4
    with black at 0 the brightness rotary knob control maintains a BT.1886 response for any given black
    level. The appropriate black level is a function of both viewing environment and personal preference,
    but a range of 0 nits to no more than 0.05 nits is generally advisable

    and this is using a prolevel CR100 meter thats much better than what most people have here. you should also run large verification test chart and post the html here. so we can see what issues youre having.

    #39711

    NoVoicemail
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    during interactive display adjustment click the third cursive “i” icon, theres a black level measurement make sure it shows 0.00 nits. i found the i1displaypro3 has light leakage so make sure youre in a dark environment to get correct readings.

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