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GH2 Color Banding Bashing
  • 54 Replies sorted by
  • @LPowell Aha, that's interesting about Rec.709. It didn't occur to me that the colour space might be encoded in a non linear fashion. I was thinking in RGB terms. But Rec.709 is the colour space used in HDTV, so why doesn't the banding occur on HDTV signals? E.g. broadcast or non deep colour bluerays?
  • @Maxwell77
    As you suspect, banding (or "posterization" as it's called in graphic arts) on the GH1/2 is primarily due to the limitations of the 8-bit color depth of the AVCHD encoder. (The image sensor itself has 12-bit RGB photosensors.) Banding effects are inevitably worse in dimly lit, gradually contoured areas such as an evening sky. The reason this occurs is because the gamma curve used in the Rec. 709 video spec assigns only a 4-bit fraction of the 8-bit color space to the darker colors. As a result, there are far fewer gradations available for encoding darker colors than there are for brighter colors.

    For minimal banding, you'll want to use an AQ4 patch at a high bitrate with -2 Noise Reduction. As @Ian_T points out, this will also preserve more random noise, which may help mask banding contours. I doubt that short-GOP patches will improve banding, as they force the encoder to divide its available bitrate among more frequent I-frames, each of which requires a huge amount of data to encode at the highest quality.
  • EDIT Just seen @sam_stickland comment above. I personally think 8-bit is the cause but equally @sam_stickland may be right.

    @Maxwell77My suggestion is to force a higher ISO (but stop down or use some ND filters) to introduce some noise to dither the image and then noise-reduce in post. Not ideal, I know, but I have shot something to deliberately provoke banding, with both low and high ISOs, and have seen the higher ISO apparently reduce the banding, which is why (like you) I have come to believe 8-bit is the cause. It might be my monitoring, of course, so take this as just an experiment. The problem is that you don't necessarily know when banding will be a problem, but I'm sure you will recognise those situations once you become aware of it.

    I'm pleased you like the GH2 - I think it's great too - so why not try this idea and see if it helps.
  • Are people really sure that 8 bit is the cause of this banding? I've never seen this sort of banding before on my DVD collection (all 8 bit), or on any of my Bluerays (all 8 bit), or on my LCD monitors (8 bit), or on anything played through my 8 bit graphics card (a Nvidia GTX460).

    In fact, even if I had a camera capable of recording 10 bits per channel, I don't actually own any hardware capable of the playing it back at anything greater than 8 bit.

  • @andres
    Hey, I use my GH2 since one year for professional shootings. The results were always brilliant. The GH2 is a very good cam. Be careful what you are saying about the GH2. On Friday I had a shooting with a very blue sky. This was the first time that I realized this banding issue. Certainly it is my fault. I underestimate the problem. But this experience is important. Everybody makes mistakes. Apart from that you do not learn something. And I never said, that the cam is bad. But color banding is a problem. Now I know this. The comparison with the RED was only an example...There are a lot of other cams which do not have these problems.

    And there is still a BIG missunderstanding. I used an UNHACKED GH2 for the shooting. When I saw the banding I hacked the cam to get rid of this problem. I did a few tests with a clear blue sky and realized the problem again. Vitaliys hack is awsome. 8 Bit per channel are a the problem. Not the hack. Higher bitrates will not change this.

    I guess there is nothing more to say. We can close this topic.
  • "I lost much money and my faith in the GH2..."
    @Maxwell77 are you a producer?
    Where did you get the idea that a gh2 could replace a Red in a professional environment.
    And how do you go out on a paid job with a hacked camera that you haven't tested previously?
    This is something that everyone does here. IF it's true what you say... than its completely your fault for not testing your equipment previously.
    Of course there are banding problems and other problems as well.
    ruined shots ? vimeo screengrab
  • @Maxwell77

    As I said, I am waiting for samples from your "ruined" shots.
  • @Alex
    You have to know in which situations the GH2 gets in trouble...Then you get really good results Only the color banding makes me mad... ;) But this is not only a GH2 problem...We cannot expect wonders when filming in AVCHD 8 Bit...This is true. I have to accept it... For many disadvantages I found good workarounds... But not for the banding problem...

    @nomad I did not know that the AVCHD standard includes 10 Bit... It is a shame that AVCHD is still 8 Bit...If there is any possibility to hack the GH2 to use 10 Bit instead of 8 Bit Vitaliy definately would did it...
    I also think that the companies have no interst to sell cheap cameras which are as good as professionell camcorders... Perhaps this behaviour will change in the future... We will see...

    My conclusion: The GH2 is a good cam but not for all situations. The main problem seems to be the AVCHD-Codec... Perhaps I will try Motion JPEG the next time... In this mode the color banding should not be so serious as in the AVCHD modes...I will try it...

    @Vitaliy Please be a bit nicer... I have not flout you or somebody else... ;)
  • @Maxwell77 what convinced you that the GH2 is really a good cam?? Its flaws are discussed in all camera forums. Also color banding. Didn't you do a research?

  • All cheap cameras have problems with banding in certain situations. There is a reason why manufacturers are limiting AVCHD to 8 bit – H.264 would be capable of 10 bit…

    The big companies are always holding pro technology back as long as they can – until someone kicks their asses, like Jannard.

    Or Vitalij !
  • @Maxwell77

    It is more and more looks like bashing.
    I am waiting for your examples.
    30-40 seconds upload to Vimeo is enough.
  • I was convinced that the GH2 is a really good cam and can do the job... I do not expected that the color banding is such a huge problem.. Its a really bad experience...Sure...But I have learnt a lot...The comparison with the RED was only an example...There a also a lot of cheaper cams which do not have problems with color banding. ;)
  • @Maxwell77
    "You can use the GH2 for professional shootings...But only for definite situations. The GH2 is not an alternative for a RED. Perhaps my expections were to high."
    [[[[[[[[[[[[[[[[[[[[[[[[

    Who on earth told you GH2 could substitute for a $50,000 cinema cam? And if you're really a pro shooter, why are you going out on gigs with a camera you're not fully familiar with? Every camera, including RED has limitations. To quote Dirty Harry, "A man has to know his limitations..."
  • @Vitaliy The videofiles are to big to upload...Sorry...For the most people the color banding in my shots are certainly ok...But if you want produce professional shots for an applicant this banding is not ok... I will bear it in mind that the GH2 is for some situations not the right choice. For the most normal situations the cam is very good. I dont understand why the AVCHD specification implement only 8 Bit per channel. With 10 Bit we would not have these color banding problems. On the other hand the enterprises must confine their professional produkts form the prosumer products... Its a very difficult situation. I guess in 5-10 years all these problems are out of date. Perhaps you can then shoot broadcast videos with your iphone... ;)

    @nomad You are right. As I say my expectations were to high. Its my fault.
  • ....but when shot and manipulated just right.....it comes awful close. :-)

    Bring on some custom curves.
  • And temporal post noise reduction like Neatvideo can deal much better with banding if it doesn't wander, but stays erratic from frame to frame.

    @Maxwell77:
    I find it quite naive to expect the GH2 ever to be an alternative to the RED. The RED is cheap for what it can deliver. The same is true for the GH2. But please have a look at the prices.
  • Thanks for the enlightenment! I still feel like the "Reference" (P and B) frames do really strange stuff with wandering blocks of garbage, that shows up especially with motion. That's probably the improvement I see, which is a motion thing, I guess. I agree, the blocking is still there in GOP1, its just that it doesn't form clicks like a bunch of middleschoolers and go wandering around the image for a couple frames. The complete image processing for every frame causes macro blocks (if I understand correctly) . . . to be recalculated each frame, rather than only every i-frame in a group of several frames.
  • @Maxwell77

    Can we, please look at the ruined shooting videos?
  • @Ian_T I get what you say about noise creating a dithering effect, but with certain colours I think thats going to be more of a hindrance than a positive (considering the cameras bias to noise in red, and it being more obvious accross different points of an images luminance profile).

    I've not had any banding that really bugged me so far, but if I did I would do what I've done in the past which is to transcode the footage into 10bit or higher, roto shape out the areas of banding (attach the roto to the track if its a moving shot) and then use filters such as various types of blurs to smooth it out accross the higher bit range. Its far from a perfect solution, which would be to somehow resample the area and dither, but its smart enough in most circumstances.
  • Sorry, I really like the GH2... ;) The picture quality is awesom...But at the moment I am very frustrated... Yesterday I had a professional shooting and huge problems with color banding. I thought the GH2 will be good for this job...But the banding made the shots unuseable... Its very disappointing. I lost much money and my faith in the GH2...You can use the GH2 for professional shootings...But only for definite situations. The GH2 is not an alternative for a RED. Perhaps my expections were to high.

    By the way, Neat Video is a good program to reduce the banding in the post...But it take too much time...
  • @Stray What I believe B3Guy is seeing is the benefits of added noise in the image. He's right about the fine noise but at the same time I believe the noise contributes to a dithering effect on the image. I could be wrong but that's the way I see it also. It might not completley get rid of it (oh...and I believe the correct term is posterization) but it helps. I have not had any problems outdoors (at least so far) since the hack but indoors...on a clear colored wall...it sometimes shows up.

    @Maxwell77...oh yes the 5Dll does have this problem. From the very first videos that came out on the 5Dll (as beautiful as they looked overall) was when I was first alerted to this problem. I would have never paid any attention to it if "some" people didn't start making a big deal about it. Now I look for it in every shot.... I hate when that happens. But what I don't get is your claim that this camera can't be used for professional use...when there are a plethora of users out there using it....professionally ,,,UNHACKED. I don't get your claim.

    EDIT: Oh....I see that it's your choice not to use it this way. That's Kewl.
  • @Maxwell77

    Sounds extreme.
    You register and after few minutes started bashing GH2 :-)
    All this "useless for a professional use" sounds like crap.
    And I still do not see any single example of this and example of your works.
  • @B3Guy
    Thanks for your response. I will try everything that can help me to solve the banding issue...Where can I download the setting-file?
    @Vitaliy
    Yes I know the problems with cheap monitors... ;) Its unbelievable that you can find this kind of monitors in big production studios...

    My assumption is that the banding appears only in very complex conditions...For example: a clear sky at 12 o´clock. I have to use an aperture at 22...Nearly closed. I guess that the less light which falls at the sensor causes these problems. For this reason a ND-Filter should help. But I have read that this kind of filter will boost the banding...It is really frustrating...The GH2 could be a very good camera...But the banding problem makes this camera useless for a professional use. The Canon 5D Mark II dont have these problems...It seems that Panasonic made not a good job... I have heart that Panasonic knows the banding problem...But there is no firmware update to fix it... What a shame!
  • Okay, but it isnt actually better image quality wise than a longer GOP, the 66M GOP12 for example, in fact its slightly less quality on detailed static elements. None of the advantages of GOP1 actually assist in curing the banding either. The noise will be better thats very true, as it won't get smeared by P and B frames, and motion will look great/very different to a long GOP (fast motion will look shedloads better/different with the GOP1). But we're not talking about a jaw dropping difference over the 66M AQ2 when it comes to image quality. Heh, sorry just got to kill the myth that the GOP1 has better overall image quality, and is therefore better to work with in post. It isn't, it's as good as (well its actually slightly lower quality than the 66M), which is in fact bloody good. See attached images of 'damn nearly' the same shot at both bitrates horribly brutalised with curve adjustments. The difference is negligible, unnoticeable really. The 66M still I pulled was from a P-frame slap in the middle of the GOP.
    66Mstill.png
    1920 x 1080 - 4M
    66Mstill_brutalcurve.png
    1920 x 1080 - 140K
    176Mstill_brutalcurve.png
    1920 x 1080 - 135K
    176Mstill.png
    1920 x 1080 - 4M
    66Mstill_curvewithclamp.png
    1920 x 1080 - 5M
    176Mstill_curvewithclamp.png
    1920 x 1080 - 5M
  • from a PURELY non-specific viewpoint, I think the GOP1 does do better. The issue I had with GOP3 was that I really was still seeing some macro blocking. Don't get me wrong, it is MUCH better than stock or other lighter hack settings, but when it comes down to image manipulation in post . . . if macro blocks are there, color balancing and grading will make those blocks pop out like a bare tit in a cold breeze, no matter how careful you are. GOP1 to my eyes really has no visible blocking. Its all a light grainy noise fuzz . . . every frame. The light noise goes a really long way in breaking up any natural banding, whereas macro blocks simply serve to make banding worse. Don't get me wrong . . . GOP3 is really very impressive. I just personally feel that unless the blocking and other junk can be dispensed with completely, there really is little point in "lessening" it. But that's just me, and I'm no pro, just an art student with (I like to think) a natural eye and knack for this stuff.