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GH2 showing fixed darker band/stripe 20 pixels high across footage
  • sam_sticklandsam_stickland
    Hi,

    I'm using the settings below on my newly hacked GH2, and I'm seeing a horizontal band of darker pixels in my 24H footage. It's all the way across the image, completely rock solid at around 800 pixels down, and the band is around 40 pixels high. It doesn't move.

    It becomes more and more obvious at higher ISOs, and is next to invisible below 400. The attached screen shot is from some ISO3200 footage, at f/3.5 on the 14-42mm lens. It's very noisy - I've drawn around where the bar is.

    One thing to note is that I'm inadvertently using a Class 6 card (can't believe Sandisk write 20MB/s on the side of it, cheeky buggers!) so I often can't record for very low with these settings (Class 10 card is now ordered!). Would this really make any difference though?

    I realise this isn't a methodical test - I've just gone straight ahead with a bunch of settings, if I get time I'll try enabling settings one by one and see which one causes it.

    I'll edit this post to include a link to the .mts file once it's uploaded, the bar is easier to see on moving footage.

    [Information]
    Comment=1080p 66Mbps, 6 GOP, AQ=3, FB x 3
    SD_Card=Any
    Camera=GH2 v1.0E
    [Settings]
    Version increment=10
    Video Bitrate 24H=66000000
    Auto Quantizer for 1080 modes=3 - Most to details
    1080i50 and 1080p24 GOP Size=6
    1080p24 FB1=2350080
    1080p24 FB2=2952069
    1080p24 Frame Limit=23592960

    [EDITED: This problem also existed on my stock firmware]
  • 186 Replies sorted by
  • rigsrigs
    Nice lines - that makes it imposible to see what you are talking about. try posting without the lines
  • sam_sticklandsam_stickland
    The lines are a good 30 pixels clear of the band top and bottom. They are just to direct the eye as it's very difficult to see in stills. I've attached another PNG without the lines though.

    The MTS files should be available in the next 25 minutes.
    00007 (0-00-02-18).png
    1920 x 1080 - 2M
  • sam_sticklandsam_stickland
    OK, I've gone through my pre-hacked footage and the issue existed there as well, it was just subtle enough that I hadn't noticed it.

    I've found additional info at it here (right click and select "Watch on Vimeo" for the comment thread)




    Jury seems to out on whether this is a sensor issue with some batches or a more general issue.

    There doesn't seem to be much point linking to my MTS files now - these other examples are the same.
  • OedipaxOedipax
    I was noticing the same issue on some ISO 3200 footage I shot yesterday using 3.62. I'm not at my home machine right now but I can attach some stills later if anyone's interested. I haven't noticed it in normal use, and even at 3200 it's not unbearable, but it did make me wonder what was happening.
  • cbrandincbrandin
    I did a little image analysis on your picture. The new patches increase low level resolution quite a bit - so defects are more visible. I can see FPN all over the image (it's not very visible without doing some image processing with Photoshop). The line isn't quite straight - it looks almost like a smear on the sensor. Maybe the sensor is just a little dirty? If it were true FPN I would think the line would be straighter.

    Chris
  • sam_sticklandsam_stickland
    On the DVXuser thread some people report that replacement cameras haven't had this problem, through sometimes they've had to replace it three times or more before getting a clean version.

    I hope that Panasonic will replace my hacked GH2!
  • sam_sticklandsam_stickland
    @cbrandin I tried the sensor clean and pixel refresh and it hasn't made any difference. I'll test and see if it jumps about when the shutter speed is changed (like the guy on Vimeo reports)
  • brudneybrudney
    well, that's a well known (or is it?) 'feature' of GH2. Thankfully it's only visible in high ISOs and is much much less frustrating than GH1s FPN. My previous GH2 (WE09) had it, my recent GH2 has it (WE1C). I wonder what kind of FPN GH3 will have;)
  • sam_sticklandsam_stickland
    @cbrandin Yup, just like the Vimeo video my horizontal band moves up the image with faster shutter speeds, and disappears completely at 1/25.
  • sam_sticklandsam_stickland
    @brudney It doesn't appear to be an issue on some cameras though. This is a message from that dvxuser thread:

    "I am agree with most of your points.i tried 2 gh2 before and i sent them back because of fix horizontal banding.for me it was defect aswell, i didn understand how panasonic can sell camera like this.also so a few people talking about it.there are other issues but you can work around them or technological limitations.
    However i bought my 3rd camera, and seems to be there is no or very litle banding. In low light situation there are still a lot going on,like 8 bit banding , postarization, strange distrubition of noise.but it looks like panasonic silently fix the problem of horizontal banding.I couldn also quite belive my self the difference between cameras i tried.my conclusion is there are good and bad Gh2s out there.may be that is why there were bot so huge reactions on this forum because some people never had this problem.
    I am going to keep this one, in good light image from camera is very good.i will still not use highest isos, but if i need to , i know i can.
    For the information, i bought the camera 2 days ago in Holland, so it is pal and serial number starts with WE1CA
    I hope this helps to some people"
  • cbrandincbrandin
    Wow, that's strange. I looked at the video and it's definitely there, and it does move around. Obviously not dirt!

    Chris
  • brudneybrudney
    sam_stickland: yes, seems like. although it's funny that the guy's serial number is the same as mine, yet I can still see the horizontal banding at high ISOs ;) anyway, it may be a similar situation as the one with GH1. Some reported very heavy FPN, some said they could hardly notice it. So it's either Panasonic selling batches of both good and bad cameras or just a difference in people's perception:)
  • sam_sticklandsam_stickland
    FYI, I've been able to significantly reduce the visibility of this banding in After Effects like this:

    - Create an adjustment layer over your footage, masking out the band
    - Raise the gamma in the adjustment layer until the band is less visible (I used Colorista, and it's a very slight raise in the midtones 1 -> 1.0321)
    - Duplicate the original footage, place it above the adjustment layer, then set the adjustment layers Track Matte to "Luma Inverted"

    The final step is necessary because the band is more visible on dark areas than light areas. If you don't do this the raise in the gamma will brighten the lighter areas of the image too much.

    What a pain in the arse! But at least the settings should be the same for each shutter speed.

    I think I will return the camera as other people have had luck doing that :/
  • brudneybrudney

    dark spot that was the main reason why I sent my previous GH2 back. Thankfully the new one doesn't have THAT particular issue anymore.
  • sam_sticklandsam_stickland
    @brudney Nothing like a bit of quality control!
  • sammysammy
    i see that line also, at high iso and little underexposed ..by the way what is the best way to clean the sensor,what products to use?i have a few dust particles that seem not to want to leave with internal pixel refresh and sensor cleaning option , i see them most at f11 and up
  • sam_sticklandsam_stickland
    @sammy Don't touch the sensor - the manual recommends to use a gentle air blower. Check the manual for the exact instructions, IIRC it's near the back.
  • cj7cj7
    hello, I just wonder, what happens if you set the zoom to the widest? (14mm in case of my LUMIX G VARIO 14-42mm/F3.5-5.6).

    I have had the better chance to see the stripe in movies shot in a darker room with few lights on, high ISO etc.

    (note: the preview image you see in the LCD seems to change accordingly depending on video recording status. what you see in the LCD is probably close to what you get as a result. So, if you see the banding while recording, you are very likely to have movie files with the band stripe).
  • sam_sticklandsam_stickland
    @cj7 The images I attached where shot at 14mm, f/3.5 on the 14-42mm/f3.5-5.6 lens.. I was doing these shots to get a feel for how much light I need, so I wanted the aperture as wide as possible.

    I'm going to get the f/1.7 20mm pancake which is two stops faster than the 14-42mm so hopefully I won't have much need for 3200 ISO. To my eye it's too noisy for use, particularly all the FPN.

    Oh, I don't think the LCD has the resolution to show this sort of FPN.
  • cj7cj7
    @sam_stickland

    hello, nice to talk to you & thank you very much for a response!

    >f/1.7 20mm pancake
    I heard a lot of good reviews about the lens. So I am also thinking to buy one. Hopefully the lens does not have the problem of banding stripe....

    >>LCD
    Maybe the stripe was only obscure with the lens at 14mm, which was not just showing (or visible) on the LCD screen.
  • brudneybrudney
    cj7-> it does, as it's a sensor issue. obviously 20mm 1.7 is a fast prime, so you have to be pretty heavily underexposed at high ISO to start noticing it, but it's there:)

    and yes, the stripe is visible on the LCD (when you know what to look for).
  • sam_sticklandsam_stickland
    @cbrandin What process did you apply in Photoshop to reveal the FPN? Would you say it was excessive or average for a GH2 at this ISO and exposure (high and under exposed)?
  • cbrandincbrandin
    @sam_stickland

    I just take a screen grab and use Photoshop "levels" setting the endpoints around the edges of the histogram. It's ugly as hell, but you can see everything.

    I think the FPN noise with the GH2 is actually pretty good. All digital cameras have FPN unless they have just crushed the blacks.

    Be prepared to be unsettled when you do the levels thing, though - it looks terrible no matter how good the camera is.

    Chris
  • sammysammy
    @sam_stickland
    is this what you seeing?this is my gh2 ,high iso,changing shutter speed makes that line go up

  • driftwooddriftwood
    I read somewhere its a prob with the 14-42 lens, can you confirm the problem on any other lenses? I have two early version gh2s and get no problems with an array of different lenses inc 14-140, 7-14 and OM 50/1.2, FD 50/1.2 etc...
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