Crushed blacks and clipped whites

Discussion in 'ZIDOO X9S' started by Emiliano, Feb 15, 2018.

  1. Emiliano

    Emiliano New Member

    Dear all,

    Anybody is experiencing this issue with our X9S ? I have an Epson Tw9300 perfectly calibrated with my htpc in Ycbcr 4.2.2 10 bit color space 0 -255.When I run Mark Widows patterns to check black and white clipping those look perfect with my htpc settup.
    When I do the same with my X9S native player, black level 17 gets crushed and whites
    bars clip.
    In order to show bar patterns correctly I have to set brightness to 34 and bring contrast to 31.
    Is that a normal behaviour ? Shouldn't the X9S output the same image as my htpc since image output parameters are the same ?
    Thank you
  2. Sarco

    Sarco Active Member Beta test group

    To many parameter unknown, ex: htpc HDMI 1.4 or 2.0, resolution 1080p or 2160p etc...
  3. Emiliano

    Emiliano New Member

    My resolution is 1080p, HDMI cable is 1.4 Nevertheless I don't see why the hdmi should affect picture quality.. the clip is 1080p@24hz. All color parameters are by default in both my pj and tv set. I see blacks crushed in both. Im currently using zidoo firmware 1.5
  4. Sarco

    Sarco Active Member Beta test group

    If you think that HDMI 2.0 is only cable stuff I do not have time to loose...
    Last edited: Feb 16, 2018
  5. n_p

    n_p Active Member

    Read this (maybe youll get a better fit playing around with YCbCR full/limited RGB full/limited):
    Remember, that you have to switch your projector to limited as well, when you change the X9s to limited.

    Otherwise - if _only 17_ black clips (and you are feeding limited)... *meh* ;) (Sacrilege, I know...)

    Afair I dont have this problem with the X9S set up to output YCbCr limited.

    Superwhites and superblacks are clipped in all modes (If you use full, and they start to be clipped below 255, use a limited signal chain - and cross your fingers that whites dont get clipped below 235).

    If you cut Zidoo a little slack, thats actually fine. Movies in all video spec get mastered to 16-235 (or the 10 bit equivalent), superwhite is mostly a thing - if somone did a wrong full/limited match somewhere in postproduction - so that even though the black level is off, signal doesnt get clipped at the high end.

    If you follow the Scott Wilkinson school of "i have this one snowboard movie, and it has superwhites, and boy do we calibrate our TV sets for that" - dont. He mostly doesnt know what he is talking about.. ;)

    Also - I dont remember if Kodi on Android can even be set do display superwhites, I think I remember, that even Kodi always clips, but you can look into that on your own.. :)
    Last edited: Feb 16, 2018
  6. SaskMedia

    SaskMedia Member

    setting to limited fixes the problem. I had super crushed blacks on my OLED panel using auto.
  7. videobruce

    videobruce Member

    It's the version of HDMI that may be the issue. ;)

  8. litlgi74

    litlgi74 Member

    I can't believe he is the editor of the AVSForum!
  9. Emiliano

    Emiliano New Member

    Thank you all for your replies :)
    I have tried everything : changing cable to version 2.0 (the previous one was marked ultra high speed anyway), switching to limited, rgb 4.4.4 ,Ycbcr 4.4.4 but to no avail. There is no way: 17 black bar keeps clipping as well as 234 white bar.
    What do you guys suggest ? Should I live with that or should I return this unit and ask for a new one ?
  10. n_p

    n_p Active Member

    Its not the cable. ;) Now that only those two bars clip, we know, that it is not a limited/full chain mismatch (the only reason I suggested you switching between limited and full).

    I remember, that I fiddled around with the brightness setting in video settings on the Zidoo (which is not a good idea, because it probably does a simple brightness transformation after the fact, which would affect all colors and very likely reduce the overall available levels) to get the first few out of black colors right - but ended up dropping it after a while (two generations of TV and Lut calibrtions later.. ;) ).

    The 234 clipping difference you very likely won't be able to perceive in real world content - even in A - B tests.

    The difference at the 17 black level means, that you've got very slight black crush. Less than all LG OLED owners are living with, btw - because we have the first three or four levels clipping, if we want "true black". :)

    So its not a huge issue, but its definitely strange, since wesk05 didnt measure it.

    Where do you view your test patterns in, so we can do a comparison. :)
    Last edited: Feb 27, 2018
  11. Emiliano

    Emiliano New Member

    I don't know guys, maybe my slight color blindness affects my judgement :) Yes, it's only two bars and I can somehow perceive number 234 flashing in the background. So I would say it's only the black one, the number 17 which upsets me a little :)
    Unfortunately I had to return my tw9300 for a stuck pixel issue and I'm waiting for a new unit. As of now, I'm running my test with a plasma LG TV set. I have the impression that disabling the auto refresh rate and resolution setting might solve the issue but I would like to double check with my vpj once it gets back.
    I'm using the patterns downloaded here
    I have tested both mp4 and avchd iso files with the same results.
  12. n_p

    n_p Active Member

    Im using the same patterns (mp4, but encode shouldnt mater), so thats a good start. :)

    To give you another "metric to go by", both brightness level mismatches would be considered by dE2000 (color difference) standards, well below a just perceivable difference on all colors, but it (brightness (deltaY)) sometimes could be the last little margin that shifts the scale. That said, dE2000 basically doesnt work at <= 5 nits, as it reports all colors as not perceivably different.. ;)

    A new color difference formula is on its way - but as it was developed by Dolby, and Calibrators dont want to have to admit, that they maybe calibrated to a formula, that wasnt the best judge of color accuracy (currently pinheaded by the "mostly in HDR space" catchphrase, so it would be more likely to get universal acceptance - but rec 709 colors are affected as well) - we now enter the realm of politics around it being implemented in the field.. ;)

    The image detail you'll loose in highlights because 234 is clipping will be minimal. :)

    Just bump this thread, if you get your set back - and Ill do the comparison as soon as I see your post. :) (Which can take a while.. ;) )

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