GH2 grain

rigs

There is allot of great progress being done to improve the performance and quality of the recording for the GH2, with many thanks to Vitality and everyone involved in the ongoing testing. I have tried several of the improved hacks and much like the GH1 have noticed significant gains that may convince me to add our current GH2 to future broadcast productions. I only have one concern with the GH2 running along side our GH1’s and that is the low ISO (160 – 400) grain that the GH2 produces. In several well lit interior and exterior tests along side our GH1’s, the GH2 has a definitely more pronounced harsh type of grain. This was noticed before on 2 separate GH2 cameras we had purchased back in Dec 2010 and February of this year. We returned them both as they didn’t stack up to the quality of our GH1’s at the time and they both produced a harsher grain then our GH1’s. We have since purchased another GH2 (in April) with hopes of an upcoming hack but even with the improve quality we still find it to have the same harsh grain as the other 2 GH2's.

Do any of you other GH2 users have the same problem or concerns with grain as us, or are we experiencing a bad lot. Your thoughts would be greatly appreciated as we are thinking about purchasing another GH2 in the next week but are a little hesitant, for fear of getting the same results as the ones before.

Thanks

fatpig

i see no grain in well lit scenes in iso 160. 400 is a different story of course. maybe post some screenshots with grain in iso 160? :)

cosimo_bullo

I'd say if anything, you'll see much more 'grain' from a hacked, high bitrate GH2 than the stock, as the hack is keeping info that before was being turned into mush. Try cinema at 160 for a change. All but grain free. We usually use smooth, but if you're looking for the cleanest GH2 footage it might be a help.

DrDave

I have exactly the same issue, it gets slightly better if you dial back the sharpening and contrast, but it is always there. I have come to terms with this as follows--for certain scenes (flowing motion), I very slightly prefer the GH1--especially now that 24p is pretty stable--but I realize that most people are not going to notice the difference, or, even stranger from an artistic point of view, if you leave the settings at "0000" many people will like the saturated color and pseudo sharpness. And I have to say, sitting far from the screen, it does look good. It looks real good. But I'm keeping the GH1 for two reasons. Reason one is for sure the grain, reason two is, if someone offered me a camera like that for $375, I would buy it no hesitation.
The hack for the GH2 is getting better and better, but I think the grain is just a function of the denser sensor. Hey, quite a few ppl really like the GH2 grain. And in certain situations, it does look filmic. While I was testing the Rigs hack today (thanks again), I just shot a few trees in the backyard at ISO 100, popped it into the media player, and like, wow. But hey, realistically, it is a very small difference and the GH2 is a great cam. We notice it because we live with all the time.
Grain wise, I have been disappointed with ETC. I expected cleaner video. But it is a very handy feature. Cant wait to see the firmware update--maybe they will dial back the in cam processing a tad more and that will split the difference in the grain.
I also think that we haven't squeezed the max out of the GH1.
Down the line, either the Canon 5D Mk3 or something similar will lay the grain to rest--you will only add it if you want it. For now, I'm enjoying both cams.
For sure double check everything in the signal path for and DSP in the chain that might give a bit more grain, but I'm sure you thought of that.

rigs

I do notice more grain with the hack. I use smooth as well and notice it in other film modes. I would rather add grain in post if needed.

DrDave

One more thing--have you tried shooting daylight white balance then adjusting the WB in post for your lights? Could be you are getting a lot of blue channel noise, or other WB noise. A long shot, but sometimes part of the noise is WB related.

Ralph_B

The red channel is actually the noisiest, not the blue.
If you want to completely eliminate it, Neat Video, properly applied, will do it. The only downside is it's slow. Neat Video will also clean up ETC mode and make it look perfect.

Bueller

@Ralph_B

Hey RB

I have NeatV, could you please give me a quick overview of your settings or do you go auto? No rush just when you get a chance.

Thanks

sam_stickland

@DrDave I've never been sure how choosing different WBs can reduce noise. Surely if I pick a camera WB that reduces the noisier channel I'm only going to end up boosting that channel again in post. Only now I'm boosting the channel post-compression - wouldn't it be cleaner to balance the colours before it's compressed?

Ralph_B

Neat Video Guide

The key thing in Neat Video is to get a clean noise sample. If you do this, everything else will fall into place. Ideally you should shoot a gray card when filming. Or you could throw the picture wildly out of focus to get a smooth area of noise. As you know, Neat Video tries to auto-detect a clean area of noise. I would say 80% of the time it does a good job, but sometimes you need to manually move the square around to find a better area. Press the Auto-Profile button again to register the new area. If the lighting and exposure doesn't change, you can use the same noise sample for multiple shots. (Neat Video remembers the last used noise sample)

Here are my recomendations for the Noise Filter Settings:

Noise Levels:
Leave both Luminance and Chrominace at 0. This is the optimum setting if you have a clean noise sample. The only time you would change these would be to compensate for a less than perfect noise sample. But it never works as good as getting a clean noise sample in the first place.

Noise Reduction Amounts:
Neat Video defaults the Luminance channel to 60%. This is good for a still image, but not for video. There will be too much pulsing between frames. Drop it to 30%. If you have Preview turned on, it may look like it's doing nothing at all, but don't worry, it is.
Chrominance channels is fine at it's default of 100%.

I've found no use for "Smooth edges" and I recommend keeping "Sharpening Amount" at 0.
"Very low freq" may be useful if the picture has large blotchy areas of noise. With the GH2, I use it with clips shot with ETC at high ISOs. For most noise jobs though, I leave it off.

Now we come to an important part that most people don't understand, and that's the "Temporal filter." After you hit Apply, you may think you're done, but you're not. In the final dialog box, you see the Temporal filter. What this does is selectively blend areas from frames on both sides of the current frame. This is absolutely essential for video to eliminate pulsing. I find that a Radius of 2 frames to be excellent for all but the worst cases. Threshold is fine at 0. The Temporal filter does slow down rendering time, so don't use any more than you need.

The results of Neat Video can be absolutely astounding and worth the long render time.

NOTE: Feel free to copy this guide anywhere you want.

Lincoln11

Hey, first thanks to Vitaliy and Chris for all the hard work. I've been too busy to post, and had only a few chance to take out the GH2 until recently. I've been in the Philippines all summer and have shot without the hack and with both versions of it. I see the grain too in low ISO settings, which is frustrating. It did not appear in the unhacked firmware footage though. I too want to use the GH2 for broadcast and indie productions, so I hope this can be resolved.

I shot a martial arts class in daylight at 250 ISO and couldn't believe the active grain in the black shirts of the people training. I understand grain in high ISO but it's definitely not good in low ISO's with plenty of light. I'm mainly relieved to see this topic, as I thought maybe I just got a bad camera out of the lot.

Vitaliy_Kiselev

@Ralph_B

Thanks for Neat Video tips :-)

stoney

Thanks @Ralph_B

DrDave

Nice Neat Video tips--I would add that if I am going to add sharpening, I do sometimes use the Neat Video sharpening. I'm assuming it does not sharpen the noise

DrDave

@sam_strickland Some cameras are optimized for Daylight. So just like NR, contrast, etc, you can use the in cam color correction, or do it in post. I've seen very persuasive tests that show you get less noise by shooting daylight, then WB/CC in post. That's because in certain lighting situations--tungsten, fluorescent, etc, you have a strong imbalance in one channel.

stoney

Tell me about it. Geez... using cheap LED lights as the only lighting sources in a dark room wasn't easy task. I looked like Greench. I saw beautiful sunlight today and felt like redemption from Shawshank.

It's possible to shift color for photo in GH. Go to WB and press down. But that didn't work for video.

Ralph_B

@DrDave

Yes, in most cameras the blue channel is the noisiest. But the GH2 is the exception. Here, the red channel is the noisiest - in fact, way noisy.

One of my low light tips is to use indoor white balance for this very reason - it supresses the output of the red channel.

Mihuel

@Ralph_B
Thanks a lot

Ian_T

@Ralph_B: I've been using the indoor white balance for the last few weeks (ever since you mentioned it on this forum) and it works like a charm. All of my images are generally clean. I've even been happily shooting up to ISO 1600 and it looks very good.

This thread is a recent example of what I shot @ ISO 800 using that tip:

http://www.personal-view.com/talks/discussion/723/my-110-mbps-high-contrast-example#Item_10

Oh...and Neat Video... though I have been using it for the last four years I have not had a use for it lately.

sam_stickland

@Ralph_B I'm still not sure I get it.

If I use a WB that's deliberately got less red in it, aren't I just going to have to boost the red channel back in post, and only reintroduce all that noise again? Only now it's boosted post AVCHD compression, which will surely be worse?

Unless some of the WB's are boosting the red channel until it's clipping?

stoney

Ralph, you meant raising color temperature to make it more bluish? The dvxuser link please?

Ralph_B

RE: Indoor white balance

Sorry for any confusion. I'm not saying you should use indoor white balance all the time. That would be absurd. What I'm saying is that when you use high ISO's, using indoor white balance is an effective way to reduce the noise. Now, when you use high ISO's, chances are it's in a low light interior or exterior at night. In both situations, indoor white balance will usually work without any significant color correction necessary.

I just don't want you to knee jerk at night and say, "oh, I'm outdoors. I must use daylight white balance". (Not to be confused with "jerk off at night". That's fine.)

DrDave

Just shoot a few seconds of video using Daylight, Tungsten and a few custom with the lighting you typically use. Shoot a WB card in the frame. Pull it into Premiere or Vegas or whatever you like and just read off the WB card. Then check the frame crops. There should be a difference in noise. Yes, you are adjusting the colors in post, no, it won't look the same, as you won't be using the camera. I tested it on my HV20 years ago, and there was a noticeable difference. As I recall, it isn't just the presets, it is the combinations of the preset and the ambient light. Since your light is different from my light, just take a few minutes to try it out--you may decide it isn't worth it. Downside is your vid may look strange till you get it into post--in a controlled lighting situation that is not an issue, as you can run a few short tests. I'm sure Ralph is right about high ISO, but I'm referring to brilliant set lighting, where you are going for 100 ISO. And there, you may find Daylight works better, or, going with what Ralph has seen in the red channel, tweak the WB with a custom setting with for example less red--or any other color-----just use a gel and a WB card and set a custom WB.

Roberto

@rigs
>I do notice more grain with the hack
Show me the grain. I find it hard to talk about what I cannot see. :-)

proaudio4

I'm finding the RED channel clips a LOT easier than the others. I shot some lower light footage during "magic hour" (the hour before sun is below the horizon). I was using smooth preset with all -2 settings.
The scene was not clipped for luminance and the GH2 reported perfect exposure. I "believe" I was set to less than ISO640 (It may have been even ISO160 - I can't fuckin remember).

Well, a lady's RED dress was noisy. When I brought it into post the illuminance histogram was less than 233, but the RED channel histogram hit and clipped at 255. Green was around 226, and Blue at around 234.

This needs to be remembered when shooting daylight setting; So, Ralph's point and others here is well taken.

bwhitz

Make sure you're using the correct Ptools version... for a while I was using 3.62 patches with the v3.61 Ptools and was getting unexpected noise. I realized my mistake when I was re-organizing my computer... ;)

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