>only a higher bitrate will allow the codec to not through out all that graduation

are you sure?
i thought the 8-bit codec itself causes the contour banding. this will never change.

I've seen this gradation step issue, although normally it's almost unnoticeable. In one case though the steps were actually moving across the picture (in one direction, diagonally) where there was a flat area of white wall in the image. This was with a manual lens and fixed exposure, so the exposure wasn't changing. Therefore I'm not sure what was happening there and why the steps were constantly moving across the image. That's the only time I've really noticed it, and it was in a shot with a single bright area (a window) elsewhere in the frame, so maybe that was affecting the exposure enough to make the gradation steps visible. Still don't know about the movement, though.

Dkitsov's idea about changing exposure is an interesting one - not one I've tried. But then, I've not seen the gradations on the LCD, only afterwards, probably because the LCD seems to go to a slightly lower quality during recording, so I wouldn't have been aware of it at the time I shot the footage. But something now to watch out for in particular scenes.

@dkitsov, you mention that this is essentially a LF effect - which I suppose it is - so I wonder if there's any post-treatment (chroma blur?) which can improve it?

Also, do you think that by changing the in-camera contrast settings, it could help to use more of the values available where it matters?

Finally, Vitaliy, any chance of the hack making it possible to record 10 bits per channel? One can always hope!!!

Edit: have looked again at the shot with the moving banding. I was very slightly changing exposure during it (just playing around with a new lens). But in a more conventional shooting situation, I could see how you might get that effect of changing exposure with lighting / shadows that vary during a shot.

Let's make a separate thread for the gradient problem, we should continue talking about it but just not in the hack thread.

//Moved from original location//
Exposing to the right saves the trouble of using LCD for anything but framing (EVF is better for focusing). the point of exposing to the right using the histogram is precisely that ( I would also turn on the highlights blinking) you will get a good exposure without picture confirmation. Good exposure in that sense that you record maximum tonal information, the image might look washed out unless you grade it in post. Low contrast Nostalgic or Cinema are always good. Though honestly I rarely see gradient problem with what I get out of GH2. For me the real reason to expect the hack is so that codec would give more attention to the areas that are below the mid-tones so when I try to grade them up if needed there would be actual detail and not just areas of flat fill with squared edges.
There is no fix for sky banding short of 8bit>16bit>color key for the sky color>blur keyed region>apply noise to the keyed region only and it must match unaffected areas or will look fake. And it is very tedious and slow, and painstaking. So no - there is no fix.
To answer for Vitaly no probably there is no easy way that 10bit color can be enabled (as he only tweaks existing firmware and does not write new one, it also may be hardwired so no firmware may change it)

Hey - my 2 cents: when the 5d2 first came out I scoured videos online to see if it was worth buying, and it was then that I first noticed banding in DSLRs as it was obvious in quite a few 5d2 videos I saw. I've seen banding in my GH2 in one shot. So I guess they're similar.

Edit: 2 shots. Both of them were areas of plain, light (not white) wall.

Exposing to the right is not a euphemism for anything. It is a name of a technique that allows one to employ the maximum dynamic range of a linear sensor. While the technique came from the digital photography world it is especially important for digital SLR video as we have only 256 step of gray to work with as opposed to possible 4096 steps possible with some still cameras.
There is a good write up on the exposing to the right on the luminous landscape. http://www.luminous-landscape.com/tutorials/expose-right.shtml

Thanks for that link. Really useful. While I've intuitively tried to do this anyway when shooting, the explanation makes huge sense to me. Relating it to audio, it's like recording at a high enough level that you hit max without distorting anything (and you can get away with the odd bit of clipping on transients). So you use all the bits you can. It's probably an exact equivalent.

A big plus is that the GH2 clips in a pretty good way, so there's no excuse not to keep that histogram going all the way up to the right hand side.

Since we can't increase the sample size, the only other way the banding could be improved would be to have more dithering. Basically you need 1 bit's worth of noise prior to being encoded into 8 bits per channel, which then effectively removes the banding but at the expense of image noise. We do the equivalent with digital audio, but in audio we have at least 16 bits to play with so we're not sacrificing significant S/N ratio.

Here's some stuff about video dither: http://en.wikipedia.org/wiki/Dither#Digital_photography_and_image_processing

With audio, some cheaper systems don't add dither because the self-noise in the system is enough to act as dither prior to A-D conversion, so if there's a video equivalent, maybe the fact we're noticing banding in these cameras is down to both the low (8-bit) sample sizes and also the low sensor noise / lack of dither. I'm only speculating - audio I know about, but not video! Anyone know?

@Mark_the_Harp

thanks for the test.

Is that situation true of film as well? As you go higher ISO does the exposure lattitude narrow and noise increases? I guess it doesn't really matter since no one uses film anymore. Just curious. I never played with varying ISO films to understand the tradeoffs.

How are you going to get the kittens to walk in slow motion. :)
don

donf,
This situation is not true with film. It is actually the opposite but for completely different reasons. For all intents and purposes, with film it is impossible to change the dynamic range of the emulsion - you have to use a different sensitivity film to do so. (changing the development time of the film (push/pull) doesn't count).
The lower film sensitivity the lower it's dynamic range, the higher the film sensitivity the higher it's dynamic range. Although for certain reasons (ie photographic emulsion non-linear response to light) the effect of ISO on the dynamic range is not very pronounced.

@xsa

What do you think about making topic for 4x5 and other medium and large format film cameras?
It is interesting to see real difference and talk about it.

Anytime one of the young kids on any production I am involved with ask me about what can they do to become a better filmmaker I say "Go buy a cheap 35mm camera with a 50mm lens and take an introduction B&W photography at the community college"