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Shadows (underexposed image) lift in post
  • apefosapefos

    I did some tests with GH2 and T3i 600D to see what is possible to do to increase dynamic range. The exposure stops was measured by camera meter and exposure compensation graphics in LCD with the camera pointed to the grass in the shadow.

    The GH2 with 128Mbps GOP3 and a good denoise with neatvideo give these results:

    Good quality image when lifting 3 stops underexposed image without idynamic

    Good quality image when lifting 4 stops underexposed image with idynamic

    This is enough for most situations, including clouds in blue sky with foliage and people under the shadow

    The T31 600D in MOV (1.3x CBR = 7.1MBps), HDR and RAW and a good denoise with neatvideo give these results:

    Good quality image when lifting 3 stops underexposed image in MOV

    Good quality image when lifting 5 stops underexposed image in HDR (lifting done in camera by two iso exposures in HDR video function)

    Good quality image when lifting 5 stops underexposed image in RAW

    RAW is more powerfull but MOV and MTS are very good if the datarate is high.

  • 4 Replies sorted by
  • matt_gh2matt_gh2

    @apefos Very good info. When you lift in post with people in shadows, how do the skintones hold up? Any change in skintone quakity?

  • apefosapefos

    Skin tones needs tests, I will do some underexposed close up shoots to see how it performs.

  • matt_gh2matt_gh2

    Great - looking forward to results

  • ShaveblogShaveblog

    Just so we're all on the same page - you're purposefully underexposing GH2 video which tends to produce a noisier image especially in the dark areas. Then you're processing with one pass of NeatVideo noise reduction to reduce this noise. Then you're lifting exposure on post to get back to normal? Do I have this right?

    I have never gotten good results by starving the GH2 sensor of light, or any digital camera's sensor for that matter. If anything, I get the best looking footage by "overexposing" or "exposing to the right" of the GH2's exposure meter, which seems to be between one and 1.5 stops too conservative. Shian and others have also noted this and they too advocate exposing GH2 footage a stop or two past zero when viewing the GH2's meter.

    NeatVideo is miraculous in cleaning up noisy footage but it's far from perfect. Nor does it ever remove noise without also removing a certain amount of detail, even with the sharpening box ticked. I would never choose to use NeatVideo unless I absolutely had to because I was forced to shoot in low available light and noise was objectionable.

    Unless this is just a proof of concept exercise to see if a narrow metric - dynamic range - can be improved at the expense of image quality, post-processing time, and overall rigmarole, I don't see the point in this. Underexposed video means you lost detail you can never recover. Adding a pass of NR means you've now done this twice. How is this supposed to be an improvement?

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