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Activity Forums DaVinci Resolve weird artifact while adjusting luma curve

  • weird artifact while adjusting luma curve

    Posted by Alessio Occhiodoro on November 24, 2013 at 2:36 pm

    Hi all!
    I just started using davinci, i filmed with a Canon 5D mkII, technicolor cinestyle profile, i’m poasting the magiclantern log here
    ISO : 160
    Shutter : 1/203.907s
    Aperture : f/4.0
    Focal length : 50 mm
    Focus distance : 0 mm
    White Balance : 1 – Sunny, Magenta 2, Blue 0
    Picture Style : CineStyle (3,0,0,0)
    FPS : 25.045
    Bit Rate (CBR) : 1.0x

    aaaand i’m having this horrible artifact when i bring down the lowlights in my luma curve;
    before applying the curves

    after (see fullscreen):

    you can see a lot of grayish noise in the blacks, that was not present in the source file, nor comes up with other cc programs (premiere, looks)….what can this be? program bug? anyone encountered the same problem? found solutions?
    thanks in advance
    Alessio

    Marc Wielage replied 12 years, 8 months ago 3 Members · 2 Replies
  • 2 Replies
  • Peter Chamberlain

    November 25, 2013 at 1:18 am

    How does it look on the grading monitor? Could this be 8 bit sampling on the UI monitor?
    Peter

  • Marc Wielage

    November 25, 2013 at 5:46 am

    [Alessio Occhiodoro] “aaaand i’m having this horrible artifact when i bring down the lowlights in my luma curve”
    What happens if you try to adjust it without curves, outside the log mode, in the normal liner mode? What about if you eliminate the LUT?

    Anything with an ISO of 160 is gonna have to have a lot of light. What do the histograms look like? You’re going to need a good meaty exposure and lots of fill in order to get detail out of the blacks on something like this. I don’t see this as a Resolve problem; this is a question of aesthetics and technical decisions.

    I do find you have to be very, very careful doing anything with curves in 8-bit material, and sometimes extra points can give you greater smoothness and less “steppiness.” But in truth, I think you can often get there just with lift, gamma, and gain 90% of the time, unless it’s really a problematic exposure.

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