Improving color gradients and static noise!

V

VeEuzUKY

Member
Despite the huge improvements with the new Firmware hacks, noise in color gradients and static noise seems still to be as bad as ever. This is my main gripe with the GH1. The camera also consistently seems to have a Gamma gain that is too high, making noise in shadow areas much more obvious and displaying most blacks as dark grays but not full blacks. To my knowledge there is no way to control the Gamma gain... one can use the Custom Film modes and increase contrast, that crushes the blacks somewhat but at the cost of loosing a lot of shadow detail and blowing off all highlights so, its not really an option.

Are there any "better" settings on the current firmware hack to improve the color gradients and static noise or a future possible path to make it possible and is there any way to somehow control/lower the Gamma gain on the GH1?

PS- Im talking about AVCHD, not MJPEG.
 
I have found a post-production technique for reducing Fixed Pattern Noise (FPN) in dim areas of a video. I shoot in AVCHD 720p 60fps, and use After Effects to convert to MJPEG at 30fps for editing. The trick is to turn Motion Blur on, but keep Frame Averaging off. The FPN is particularly noticeable when panning the camera, and Motion Blur conceals it pretty well. Frame Averaging is undesireable, as it would actually emphasize the FPN.
 
Cross posting this from the pulsing I-Frames thread:

Here is my 2 cents:

The GH1 has some AVCHD codec issues, pretty nasty at times, a painful thing because often the picture is very good. The GH13 has the same exact codec issues, regardless of gop or bitrate setting, but they are much more mitigated due to brute force bitrate increase. So this is the same stuff as seen on stock firmware. The codec in the GH1 seems to hate large areas that are in focus but are simple, such as solid wall colors, and like to put 'pulsing' or noticeable artifactyness there. I wish we could replace the codec with the code from x264, which is better than many commercial coders, how impossibly hard this might be I don't even fathom, even with hardware encoding many routines could still be tweakable, but finding them and changing them in the way we are changing values now in the firmware... I can only hope.. anyway I digress, I just don't think some of the pulsing, and artifacting on blank surfaces is fixable with the existing bitrate and gop tunables.
 
I would like to say, I've done some testing with the hacked firmware and very low light dealing with half black scenes and such.. I have some advice on how this kind of thing can be mitigated, or what the codec might be up to, from my experience with xvid and x264 encoding..

Its not so much an issue of things or the scene being 'underexposed', but rather underexposed in comparison to the rest of the scene, because if the whole scene is underexposed, don't really get the problem.

For example, bright foreground, stuff on the right side of the scene, in the left side you can see a colored blank wall in the background. Everything looks great, except the colored wall in the background, which appears fairly artifacty and nasty, and it makes u cry a little because the entire rest of the scene looks incredible.

If you download low bitrate xvid dvd rips you see this kind of thing all the time. h264 is different, but it can end up doing the same thing. Its not seen to much in x264, because x264 is such a good encoder..

I don't think this can be fully fixed by just the GOP and bitrate tunables, however the bitrate does mitigate it to some extent.

One thing that does help mitigate, besides having your scene evenly lit throughout and without solid colors or gradients that are very large (which is a silly thing to limit yourself by), is just shallow DOF blur, the GH1 codec seems to encode blury stuff very nicely... its just those very simple solid / gradient in focus areas...

Just my 3 cents.
 
We need to increase I frame in order to get better codec and higher bitrate in low light/detail situations...
 
Have you tried adobeRGB setting?

Have you tried adobeRGB setting?

This flattens the response, well it seems too, use std settings and shoot some footage first with srgb, you'll see it camera set-up, first icon, menu pg 4, 2nd icon down. Shoot the footage with that and then flick to Adobe rgb, shoot that, see what you think, then try with the smooth and bringing the contrast down and sharpness.

Edit, have just tied it again myslef to make sure am not goin blind, just replayed in-camera, the differnce is there to be seen, see if this helps with the static noise-gradients?
 
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The GH1 is also a very clean sensor; this can be very tough with 8bit codecs. Dithering slightly is also a way to handle gradient banding. Either in post or in camera by shooting at 160 or 320iso. With the new AVCHD, the one thing you notice is the GH1's noise used to look like clumps of mud when increasing ISO; now the noise with higher ISO's is recorded as noise that is more grain like then mud clumps of the old AVCHD.

Also shooting AdobeRGB is good.


Pappas
 
Pappas, am seeing the fine noise too, its

Pappas, am seeing the fine noise too, its

gorgeous, LOL, honestly though we are seeing real quality with the GH1 AVC, my only request would be CBR rather than VBR though, then we could step up a gear, 40mb/sec CBR 25/24P would be incredible.

Note: have got my eye almost pressed to my plasma and my HD screen laptop and the IQ is incredible, it really looks top notch HD. Vitaliy has set the bar very high for Panasonic GH2.
 
jobless said:
We need to increase I frame in order to get better codec and higher bitrate in low light/detail situations...
Click to expand...
Great! how do we do that or at least move towards that direction? Im all game for it. We need to find a way to make it happen!:2vrolijk_08:
 
Adventsam said:
This flattens the response, well it seems too, use std settings and shoot some footage first with srgb, you'll see it camera set-up, first icon, menu pg 4, 2nd icon down. Shoot the footage with that and then flick to Adobe rgb, shoot that, see what you think, then try with the smooth and bringing the contrast down and sharpness.

Edit, have just tied it again myslef to make sure am not goin blind, just replayed in-camera, the differnce is there to be seen, see if this helps with the static noise-gradients?
Click to expand...

Can't find the SRGB or Adobe RGB settings on my GH1 anywhere. Went through all the menus. Is this something that is added with one of the later hacks?

Best,
-Tim
 
Its under the camera icon?

Its under the camera icon?

Press menu, camera icon at top, goto pg4, drop down 1, colourspace , SRGB or AdobeRGB, click on it, AdobeRGB?

Cheers
 
Adventsam said:
This flattens the response, well it seems too, use std settings and shoot some footage first with srgb, you'll see it camera set-up, first icon, menu pg 4, 2nd icon down. Shoot the footage with that and then flick to Adobe rgb, shoot that, see what you think, then try with the smooth and bringing the contrast down and sharpness.

Edit, have just tied it again myslef to make sure am not goin blind, just replayed in-camera, the differnce is there to be seen, see if this helps with the static noise-gradients?
Click to expand...

What do you mean by std settings? Are you talking about the Standard film mode? Or are you talking about a mode other than Creative Movie Mode? Adobe vs sRGB seems to have no effect in CMM, so maybe you're talking about another mode?
 
PappasArts said:
Hey Chris,

I shot side by sides while ago , and the AdobeRGB was different- flatter than sRGB.

Pappas
Click to expand...

Was that videos or photos, because the setting for Adobe RGB and sRGB is in the photo menu. And any of this make any difference when transcoding footage (as in would Adobe RGB be not compatible with FCP 7 or something)?
 
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