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GH4 - curious issue with RAW development? edit - think we've got it narrowed down ...

Discussion in 'Panasonic Cameras' started by jurgen, May 11, 2014.

  1. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    Might be an overanalysis, but I've been shooting a lot of stills on my GH4, and because I normally edit in ACR+Photoshop (for which there is no GH4 RAW support yet), I've pretty much been jpg's only to this point.

    I decided to give Iridient and PhotoNinja a go earlier today, and I had some strange discoveries.

    In both programs, at between 100% and 200% view, there are what looks like dead pixels throughout the frame (maybe 10-15 scattered across).

    They look like this:

    http://imgur.com/FxCJ8rl
    http://imgur.com/5H2RGHU

    And at first I thought I just needed to run the pixel remap, which I did a couple times, to no avail. All spots still there, still in the same position. So then I started to worry that maybe I had a serious dead pixel problem which would show in video, so I shot a bunch of different stuff at 4K, cropped way in, and the image was clean as a whistle.

    So then I got curious, and I started downloading every other RAW GH4 photo that I could find (a whole range of ISO's and shutter speeds) from five different sources, including a couple Spanish sites and imaging-resource.

    Here's what I found on imaging-resource, and every other site (marked with arrows, might need to zoom in a little):

    http://imgur.com/h1sMlyG

    Link to download: http://www.imaging-r...sonic-gh4A7.HTM

    Every single RAW photo from six different GH4's has this black "noise" in it, at shutter speeds from 2 seconds to 1/8000 and ISO's from 200 to 3200 (high as I looked). It looks like dead pixels, and it responds to the dead pixel filter tool in Iridient, but it's weird, because it's pervasive throughout every single photo from every camera I've seen. Is it possible this is an artifact from the GH4's image processing, or perhaps a hitch in the way Iridient processes images? For what it's worth, some of these spots (though not all) also show up in Photo Ninja - this is, again, true for all six cameras, every single photo.

    Any thoughts, anyone?
     
  2. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    First thing I'll say it was a mistake to jump in and run pixel mapping twice on your brand new camera!:its quite possible there was nothing wrong.

    Could it be a problem with Iridient's RAW conversion, and a better GH4 profile might appear in some time?
    I would first look at processing before declaring anything permanently in t'internet by creating your dodgy thread title.

    Your "LarsLeibgott" thread on DPR got the same response as I put forward, and thankfully hasn't turned into an argument. Hope it gets sorted.

    As for pixelmapping when not needed : possible downside : what if the function is strict/keen enough to find false-positive dead pixels : you've lost them forever with two runs.A minor deterioration at worst, but it is a function that should only be done when real dead pixels crop up.
    I remember a very old thread about an e-pL1 user who was wrecking his sensor by running pixelmapping very often, for no good reason. It was a bit bizarre.
     
  3. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    "First thing I'll say it was a mistake to jump in and run pixel mapping twice on your brand new camera!:its quite possible there was nothing wrong."

    Why is this? What are the possible downsides?

    I've spoken with Brian Griffith, the guy who created Iridient, who says that the only change he may make in the future would be to turn on dead pixel filtering by default for GH4's.

    -edit- Perhaps you're right.

    In regards to pixel mapping, I remember the E-PL1 thread as well. I believe (if I'm not mistaken, and I very well could be) that the issue was actually that he was confusing long exposure noise for something else.

    In any event, I don't believe you "lose pixels forever" to the pixel mapping process - the camera takes an image, and then "zeros in" on any hot pixels and maps them out in the future. The next time you pixel map, you don't start from the previous one - it takes a fresh photo, and maps from there. Any "false positives" that were one-offs would come back to life.

    -EDIT EDIT - I should also mention about the user name on DPR - Jurgen is my real life given middle name, and what I go by. "Lars Leibgott" was the name of a character in the video game XCOM, which I was playing when I made my DPR account. "jurgen" was taken :smile:
     
  4. w7ox

    w7ox Mu-43 Regular

    64
    Jun 18, 2010
    Phil Wheeler
    Try a different computer?
     
  5. bg2b

    bg2b Mu-43 Regular

    53
    Dec 22, 2009
    Berkeley Heights, NJ
    You don't lose pixels forever by running pixel mapping, so don't worry about that part.

    I suspect Panasonic is just not overwriting the mapped-out pixels in the RAW file with interpolated data (i.e., that the RAW data is really exactly what came off the sensor, probably compressed, but not RAW+pixel fix). I don't have a GH4, but I know for sure that this was the case on the GH2. I had one of the early ones and found a similar issue in the GH2 RAW files after processing under Lightroom. In that case the GH2's sensor architecture tended to produce diagonally adjacent pairs of stuck pixels which Lightroom didn't fix correctly. The same issue happened in dcraw, which doesn't do anything fancy, so it was definitely coming directly from the sensor. In that case I went so far as to write some little utility based on dcraw that could be used to patch up the GH2 RAW files to fix the stuck pixels; I and a few others used it for a while until Adobe fixed Lightroom's processing for the GH2.

    I'm sure once the various vendors get around to dealing with the GH4 properly, it'll all be sorted; just be patient.
     
    • Like Like x 1
  6. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    For sure. A friend on a different forum hex edited some files from imaging-resource to open in ACR, and the black spots completely disappeared. Perhaps it's Iridient, perhaps not; either way, not something I'm going to get worked up over (especially considering it's happening in every camera).

    Cheers!
     
  7. w7ox

    w7ox Mu-43 Regular

    64
    Jun 18, 2010
    Phil Wheeler
    What results do you get with SilkyPix?
     
  8. GFFPhoto

    GFFPhoto Mu-43 All-Pro

    Feb 24, 2013
    I'm glad you found a fix! I sure would like it if you edited the attention getting thread title. It seems misleading since you found a fix.

    Thanks Jurgen :smile::2thumbs:
     
  9. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    Done and done. I didn't intend for it to sound attention seeking (though in retrospect I certainly could see how it might come across that way) - I tried to do my due diligence and narrow down on what was going on, especially when I saw it in all the files from a bunch of different sources.
     
    • Like Like x 1
  10. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    SilkyPix is clean - not a single spot from any photo, any camera.

    EDIT - Also just did a 600% punch in on 4K video - no sign of any dead pixels/strange noise.
     
  11. w7ox

    w7ox Mu-43 Regular

    64
    Jun 18, 2010
    Phil Wheeler
    Interesting -- and once you were able to use ACR you saw no spots. That is encouraging!
     
  12. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    Encouraging, certainly.

    Most (or least, depending on how you look at it) encouraging to me is that fact that it occurs on every GH4 - if it were just mine, or just any particular one on a review site, I'd write it off as a poor copy and get it swapped under warranty. But it's all six copies I've looked at! Which to my mind has to mean something's up in the processing chain somewhere, either in-camera or in RAW development through Iridient/PhotoNinja.
     
  13. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    More interesting:

    I've just downloaded some GX7 files off of various review sites and opened them in Iridient. Guess what?

    http://imgur.com/BkBdBYe

    So every single Panasonic RAW file I've opened it Iridient has displayed these spots. Perhaps it's not the camera after all.

    -EDIT- make that GH3 files as well.
     
    • Like Like x 1
  14. GFFPhoto

    GFFPhoto Mu-43 All-Pro

    Feb 24, 2013
    Good to hear, and I imagine its quite a relief!
     
  15. w7ox

    w7ox Mu-43 Regular

    64
    Jun 18, 2010
    Phil Wheeler
    That is reassuring since I have a GH4 coming (one day). I've never seen an issue with the GH3, so .... .
     
  16. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    Do you by any chance have any of your GH3 RAW files handy that you could put into a Dropbox link? I've looked at GH3 photos from four different sources now - imaging-resource, photographyblog.com, and two people who had hosted online - and found these in all of them on Iridient.

    If you've got any that you'd be willing to share (and if not that's okay too!), I'd love to take a look.
     
  17. w7ox

    w7ox Mu-43 Regular

    64
    Jun 18, 2010
    Phil Wheeler
  18. jurgen

    jurgen Mu-43 Regular

    120
    Jan 27, 2014
    Yup, they're there -

    To the right of the cord running in the corner (left of the vertical wooden post):
    http://imgur.com/XSZdiyh

    On the TV remote:
    http://imgur.com/w81Ap4I

    Wall above the cords:
    http://imgur.com/Z0XoWIH

    There are more scattered throughout the frame - though, again, I'm hesitant to say whether they're actually there at all. I think it's a RAW developer thing.

    EDIT - I should also note that the file looks great, with no signs of any black dots, in ACR.
     
  19. w7ox

    w7ox Mu-43 Regular

    64
    Jun 18, 2010
    Phil Wheeler
    No surprise, after your earlier posts.
     
  20. Ulfric M Douglas

    Ulfric M Douglas Mu-43 Hall of Famer

    Mar 6, 2010
    Northumberland
    Good man Jurgen :thumbup:

    What? some kind of command-line utility, or something useable inside another RAW processor?