GH2 Horizontal and vertical lines on GH2 footage - problem

K

katig

Member
I have a problem with new GH2 (model WE1G) - fixed horizontal lines while tilting and vertical lines while panning. I am aware of famous banding issue but this is not it. I am also aware of gradient banding, also not a problem. As you can see on my footage (GH2 WE1G, CANON nFD 1.4@2.8, HBR25p, ISO 160, 1/50, ORION DRIFTWOOD av.95Mbps, LED 5600) when I start tilting on one-color surface (white wall for example), these dark horizontal lines appear. It is easier to spot it when out of focus. Also, not so pronounced, but when I start panning you can see vertical lines (specially at the and of clip on out of focus table footage). I tried every possible setting combination (f-stop, iso, shutter speed, film modes, other patches (sanity, flowmotion, quantum x2...), lights (yes, it is visible at daytime on the sky), other lenses (canon fd 24, 35-105 and panasonic 14-42). To make a long story short, in every situation when filming uniform mid and high tones without special detail (walls, sky and similar) these lines appear - it almost feels like dirty lens but I checked that too. Maybe they even exist in more detailed footage too (like trees, stones, water...) but because of too much detail I cant see it. This is a serious problem for me. In a short period I am about to shoot a commercial and I planned to use the gh2 as main camera (instead of mark II, and because of all those great footage I see from other gh2 owners), but now I am not sure. Did someone else have same problem? Any advice?

http://www.youtube.com/watch?v=TvfgAvaTxO8&feature=g-upl&context=G2c3f4f8AUAAAAAAAAAA
 
You are pushing the memory card with those settings. I've seen similar happen on the GH1 when I was near the limits of the memory card. Perhaps test a lot less aggressive hack settings first to see if the problem goes away? Then you'd atleast know. Also, you should use a flatter film mode settings when shooting and later use 16 or 32 bit color filters in post to adjust for the desired contrast. This should help avoid some posterization a.k.a. "mud" that is present in your material.
 
This was shot with Nostalgic film mode, -2,-1,-2,-2, and I must admit it is not flat enough for proper c. grading but that's the flatest I can get within camera. In Smooth this effect is even more pronounced. My cards is Transcend C10, decent cards, got two of them and with both is the same thing. But, my biggest concern is that this effect is viewable even on panny's own 1.1 firmware (i need 25p), without any 'hacks'. Maybe some other settings in my camera is causing this problem? I tried to tweak all the main ones: iso, shutter speed, film modes, hacks, 25p/50p, f-stops, lenses, light (tungsten/led/sun), an it is still there. Very strange. I am asking this whether to find out is it a fault camera or common GH2 problem with non-static scenes (panning, tilting, handheld...) because I just bought the camera. I know that mark II 'hates' midtone surfaces but this is not gradient banding (gh2 is much better with this common issue).
 
I worked on the GH2 with the original unhacked firmware, but only 24p cinema mode gave good results back then. Did you try that for comparison? 25p is a new feature and may not be ideal for the camera. You could also try a sensor burn in, film a steady and even light source for an hour at ISO-100 with +3 stop over exposure and see if it improves the situation (at own risk, of course). Your material looks a bit muddier than I would expect from a GH2.

Here is a YouTube clip from a GH2 test from last summer: http://www.youtube.com/watch?v=AI4sqyZ-7sw

Do you see anything that resembles what you get? It might be too steady scene for comparison, however.
 
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http://www.dvxuser.com/V6/showthread.php?174654-Low-Light-Streaks-Is-my-camera-faulty/page56

24p same thing. Well, it seems to me this is very similar to known GH1 banding problem. If this is true, I am pretty screwed :)

Quote from the listed thread that gives very accurate description of my problem:

''
Been playing around with the GH1 in extreme low light and I've noticed a few things:
Banding is less likely to be noticeable in highly textured areas that are in critical focus.
Foreground objects are less prone to noticeable banding as they appear higher texture.
The fixed pattern noise, rather than the flickery banding, is less noticeable if you hold the camera very still.
I've noticed that if you're shooting things in very low light and are having banding problems you can try framing closer to your subject, eliminating things that aren't going to be in critical focus...the texture of critical focus makes the banding less obvious. Cameras with a higher bitrate codec will do better because they're going to be resolving more detail. Defocusing your background will not solve banding.
''
 
Do try the sensor burn-in, it helped a bit in one of my GH1's. Just avoid over heating the camera when shooting a light source for an hour. Place something between the camera and the lamp to make the light as even as possible to the camera and adjust the light so that it's barely +3 stops. The problem resides mostly in the red and blue channels in these cameras, so separating the channels in post production allows some cleaning without eating too much of the sharpness.

Sharpness mostly comes from the green channel, which is the only full bandwidth channel. Of course, if your hues rely more on the blue or red channel, it will show as softer and more posterized image in the final result.
 
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Perhaps the Youtube compression hides the symptoms, but the problem doesn't look that bad to me. I think in the context of a commercial, where the viewer is only paying attention to content, and the shots go by in a few seconds, the issue will be unnoticed. However, in the interest of being constructive, banding is lessened when the camera is set to 400 ISO. Lower ISOs actually increase banding. Try shooting at 400 ISO and see if the problem goes away. There are other threads that have confirmed this.
 
That's the equivalent of using a flatter film mode. Pumping up the ISO brings noise floor higher thus lessening contrast and masking other things. Increasing contrast in post makes the noise more visible. This is not always a bad thing and there is usually a sweet spot, which could well be at ISO-400. After spending countless hours of studying the mud problem of GH1, I am finally getting useful results at no higher than ISO-640.
 
Aki_Hartikainen said:
That's the equivalent of using a flatter film mode. Pumping up the ISO brings noise floor higher thus lessening contrast and masking other things.
Click to expand...
I believe it may also have to do with how AVCHD compression works. Lower ISOs have less noise so backgrounds with less detail (blue skies, white walls, etc.) get compressed which causes banding. The raised noise floor of say ISO 400 is a sweet spot that significantly lessens banding because AVCHD sees the noise as detail and doesn't compress it as badly. And at 400 ISO, the noise doesn't look ugly, in fact it looks fantastic.
 
It is possible to lessen the banding in post production using grain management. Here is an example http://www.fourseasonshd.com/blogGradingLarge.png

If you look especially at the shadow part of the image, the graded version with added film grain looks less like DSLR footage. Unfortunately it is very processor taxing and renders slowly, at least on a few year old dual Opteron.
 
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Well, that 'mud' is mostly result of youtube compression. After some more testing, I'll be fine within very slow and very fast pan/tilts. Also +1 and +2 sharpness setting helps, and I really can't explain why. Thank you for your answers.
 
After a lot of head scratching and many days and nights of testing and, of course, having the great hacks available, finally this came out of the GH1:

blogGradingFinal.jpg


Most of the banding and posterization and "mud" has finally been eliminated. No noise reduction filters were used, just color filters on the lens and grading in GoPro Cineform First Light and After Effects. Noise texture was added in Sony Vegas, which was the only software that rendered noise in reasonable time. This gives me great hope for the GH2, now that nearly mud-free video can come out of GH1. Banding and posterization in the beginning made the camera useless for cinematic purposes. Now, not so much. I urge anybody to have a look at the full size image (link below) and see what you think of it.

http://www.fourseasonshd.com/blogGradingFinalLarge.png

And here is the YouTube link: http://www.youtube.com/watch?v=Yh8cKMYiftI
 
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