The three most misunderstood GH4 settings – PART 2: Master Pedestal

Be careful what you ask for. Adding more “professional” features to a camera means adding features that 99% of users shouldn’t mess with.

In part 1 of this series, I attempted to shed some light on the behavior of the very opaque “Luminance Level” setting. Because of how different applications interpret YUV luminance levels, there’s no cut and dry answer about which setting is best for your workflow. Luckily, the topic of today’s post is much easier to understand.

Master Pedestal

In short, unless you have some very specific production workflow need that requires you to match black levels (like live broadcast for example) then increasing Master Pedestal above zero accomplishes nothing except for wasting some of the precious few 8 bits you have to encode your image. There are people on the Intarwebs suggesting otherwise, so let me say this very clearly: Increasing the Master Pedestal will NOT increase shadow detail nor will it decrease shadow noise.

Rather than try to explain why this setting exists and why you would want to use it, I’m going to use some examples to show you why you almost certainly don’t want to use it at all.

Master Pedestal 0
Master Pedestal +5
Master Pedestal +10
Master Pedestal +15

You may look at the above examples and conclude that increasing the Master Pedestal is a good tool to reveal more shadow detail and maybe even reduce some of that nasty shadow noise, right? Sure looks like it, huh?

Turns out our eyes are notoriously bad at picking out information in shadows (codecs actually rely on this fact.) This is one case where you can’t trust your peepers. We need another way to look at what was actually recorded. Enter the trusty histogram.

Histogram of all four settings overlaid

See, even at zero, my exposure was such that I wasn’t crushing my blacks. (Remember, I was purposely over-exposing.) By increasing the Master Pedestal, I didn’t increase the amount of shadow information recorded…I actually decreased it. The exact same picture information got crammed into fewer bits (that’s bad, that’s how you get nasty 8-bit artifacts like banding) because a nice hunk of the bottom end was wasted. To put it another way, adjusting the Master Pedestal up increases the compression of the data.

The better tool to reveal shadow detail is the “Highlight and Shadow” setting. In the final entry in this series, I’ll demonstrate exactly what that setting does. If you’re used to working with curves on other cameras or in post, you might be surprised to learn what this setting actually does on the GH4.

Take away

  • Master Pedestal should only be adjusted to match cameras or other specialized production needs. If you need to adjust this setting, you already know why.
  • Master Pedestal does not allow you to record more shadow detail, it only shifts the absolute black point.
  • There are better ways to “open-up” shadows that don’t waste the precious little data that can fit in an 8-bit codec.

9 Replies to "The three most misunderstood GH4 settings – PART 2: Master Pedestal"

  • Marshall
    October 30, 2014 (12:27 pm)
    Reply

    This series is really informative, thanks for putting in the work and gathering the data. I had decided to not mess with Master Pedestal because I didn’t understand it, it is nice to know I am not missing out. Looking forward to the next one.

  • Travis Kelleher (@TravisKelleher)
    October 31, 2014 (11:54 am)
    Reply

    I agree with Marshall, this series is very informative. I like your approach to shedding some light on all of the settings in this series.
    The histogram overlays are particularly useful. Thanks for taking the time to do these comparisons.

    • joe12south
      October 31, 2014 (11:58 am)
      Reply

      Glad to hear they’ve been helpful.

      I think for my next post I’m going to show comparative images between the Metabones Speed Booster and the much cheaper RJ Photo Lens Turbo.

  • Dennis L. Sørensen
    February 22, 2015 (8:59 am)
    Reply

    Hi there.

    I absolutly agree with you on this topic. Many times people use the Master Pedestal totally wrong.

    But. As i see it. It’s the same thing as useing TechniColors CineStyle for the Canon DSLRs.. Because.. you are not recording any more information. Infact; You are recording less information, but since CineStyle cramps in the highlights and shadows, it seems that there are more information.

    But sometimes, this can be good. A scene with a lot of contrast (let’s say a sunny beach with a unbrella that creates a very dark shadow. The camera wont be able to record both the very overexposed highlights of the sand and still record the underexposed shadows from the umbrella. In this case, CineStyle will push the highlights and shadows into the histrogram again and thereby recording the data. But obviously you end of loosing som of the midtones because of this.

    And i guess that the master pedestal can be used in this senario. Tho i would use the Contrast setting in the picture profile instead.

    Let me know what you think. 🙂 Thanks! 🙂

  • IEBA
    February 26, 2015 (9:40 pm)
    Reply

    And here you clearly understand the value of every bit in an 8-bit codec, as opposed to the 16-235 luminance value article where that wasn’t mentioned. Hmmm.

  • Sumanth Kuduvalli
    March 3, 2015 (7:53 am)
    Reply

    Wonderful! a real insight to many key things on the gh4. Thanks

  • Andrew
    July 1, 2015 (9:56 am)
    Reply

    Hi, After following some setting advice on the Master Pedestal and Picture Style settings I was seriously regretting buying the GH4. While researching the Luminance Level settings I found your series on these menu options. It’s refreshing to see your explanations backed up by the scope readings. Anyway, the result from dialing back the MP & Picture style settings reduced the noise in the blacks to the point where I’m excited about the camera again. Your advice on exposing to the right is also excellent. I’ve noticed that the zebras in the GH4 are very conservative and show while there is still some highlight info. Now that I’m taking their presence with a grain of salt my exposures are improved and noise is reduced furthermore. Thanks for these posts, they are f* awesome.

    • joe12south
      July 1, 2015 (11:34 am)
      Reply

      Glad the posts have helped.

      I sometimes get the feeling that many of the people releasing special sauce “profiles” into the wild are building their settings based on what they think *should* work from other cameras rather than what they’ve observed actually *does* work.

      The GH4 is a great tool, but its image is very brittle. Hopefully the V-LOG profile will give us a bit more wiggle room.

  • rollibarron
    January 28, 2016 (3:47 am)
    Reply

    what if -15?


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