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-   -   GH1 & GH2 color issues (skin tones) (http://www.dvinfo.net/forum/panasonic-lumix-g-gf-gh-gx-series/503618-gh1-gh2-color-issues-skin-tones.html)

Guy Smith December 15th, 2011 03:08 PM

GH1 & GH2 color issues (skin tones)
 
I use the GH1 & GH2 at work and have a 2nd GH1 that is my personal camera. Overall the cameras work well and were the best (only) choice for the type of work that I do. At work I produce training and promo videos for a manufacturing company and my personal work is mostly interviews.

My personal GH1 has a couple of issues. It occasionally captures green still images, and when I say green, I mean completely green. This is after a manual white balance, and video recorded under the same controlled lighting and without changing settings or powering the camera off looks fine. This issue is random, and powering the camera Off/On will (eventually) solve the issue.

The other issue is more disturbing: certain skin tones are desaturated. In one interview a young woman had desaturated areas above her upper lip (looked like she had a mustache), on her forehead, and on the side of her face.

I sent the camera to Panasonic's McAllen service center with an 11 x 17 paper printed with three images that showed the issues. I had captions under each image and arrows to point out the desaturated areas in the video frame grab. I received a request to provide them with the original files, which I did. After about two months I received the camera back with a note telling me that for the still image the white balance had been set manually, that I had done it wrong, and to go read my manual. As to the desaturated skin tones, their response was that "images captured from video will be low resolution". I never once mentioned resolution...

About 10 days ago I shot an interview with the GH2. It was shot with a Nikkor 105mm f2.5 portrait lens in partial shade with a soft gold reflector to add warmth. I manually white balanced balanced before adding the reflector, and the resulting video has green tinges in the transition area between highlight and shadow (chin line, neck). Last week I bought a LED video light from Calumet and tried it with our GH2: the green tinges were much more noticeable. The light came with an incandescent filter, and with that in place skin tones were orange - with a very strong green tinge.

I tried the light with our Nikon D7000 (on AWB) and there were zero issues with the color using the same light.

I saw a wedding demo reel here yesterday. It was shot with a GH2 and the work was very nice - except for the slight green tinges in certain skin tones. Not immediately noticeable, but very visible if you are looking for them.

At work I use our GH1 and GH2 with the 14 - 42 and 14 - 140 lenses. For interviews I use a 60's vintage Nikon 105mm f2.5, and I specifically chose this lens over the newer Ai version because the older lens coating renders warmer looking skin tones with the Panasonics.

I've tried manually tweaking the color balance toward magenta, blue/magenta, and yellow/magenta. But then I get orange or purple skin tones... with green tinges. I've also tried using a 3-wheel color corrector in post, but the results are disappointing. The best result I've had with the cameras is setting them to "Nostalgia".

I'm wondering if anyone else has had difficulty rendering accurate skin tones and, if so, how you are mitigating these issues.

Jeff Harper December 16th, 2011 12:06 AM

Re: GH1 & GH2 color issues (skin tones)
 
Hi Guy, I have had serious issues color balancing the camera indoors, and in fluorescent light it can be really bad.

The first thing I did to rectify things was to switch to all Panasonic and Olympus lenses, it helped. A Tamron I used had horrible color rendition under certain conditions, in one church the footage came out so badly it was almost not salvageable for use when mixed with my other cameras later. There were other times it looked fine, but as I learned eventually, the Tamrons really just suck overall for my use.

I do still have a Sigma for Olympus lens, and it too is really warm indoors much of the time. My solution has been, most recently, to run my WB using the K adjustment and to run on the cool side. The footage warms up, usually, very well in post, and is easier to work with than overly warm footage.

Re: the GH1: Lens choice choice can and will have an impact on your colors with the GH2, but with the GH1 the issue is magnified. When I use the Panasonic 45mm F/1.7, the GH1 works pretty darned well in low light, but when I put the Sigma zoom on, it can look pretty bad.

Your issue is very real, and I've just suffered through it, worked around it, no real pat answer that I've found, sorry to say.

Kevin McRoberts December 16th, 2011 10:01 AM

Re: GH1 & GH2 color issues (skin tones)
 
This is only using a GH2, so I'm not sure how it translates to the GH1...

I've also found the green cast, especially at higher ISO and especially when slightly underexposed. My "solution" isn't very elegant: I manually shift the color in all whitebalance settings to +5 magenta.

Guy Smith December 16th, 2011 01:37 PM

Re: GH1 & GH2 color issues (skin tones)
 
I agree that lenses make a huge difference in color rendition. At work I use the Panasonic 14 - 140 and that lens also has a green cast with the GH2. Some Nikkor Ai lenses render a very noticeable purple/green cast, whereas the older non-Ai lenses with the brownish coating render much warmer skin tones. Minolta MD lenses seem fairly neutral but lack the warmth of the older Nikkors.

I've been looking at showreels and movie trailers shot with the GH1 and GH2 and have seen the same image defects I've noticed with my cameras. The cameras work great for my day job, but I've pretty much lost the desire to shoot interviews because I can't get the nice skin tones that I was able to get with my XL1 and HV20.

Here's the last interview I shot with the GH2 and Nikkor 105mm that shows the green tint in the transition area between highlight and shadow (I did some cc work in Vegas to reduce the green cast): Roxy - YouTube

There has to be a way to deal with this in post...

Jeff Harper December 16th, 2011 02:29 PM

Re: GH1 & GH2 color issues (skin tones)
 
You guys really do help me with this discussion. I had to reshoot an entire video with my XA10 because it was all interviews that looked like crap on my GH2, and this discussion helps me to see it is not because I'm doing something wrong that my interviews can look weird. Thanks.

Roy Feldman December 17th, 2011 06:26 AM

Re: GH1 & GH2 color issues (skin tones)
 
The roxy video looks a little overexposed and the areas you mention look to me like what happens if you try to pull down over exposed highlights where there is little room to move because it is an 8 bit file.I see artificial color in the transition area from over exposed to exposed. On the GH1 I have set my white balance to have a +1 magenta bias, the GH2 with the new firmware seems to be remarkably better in this and the old "go to" setting (smooth -2 everything) needs to be looked at again because of changes to the NR and the fact that the color does not change when record is pushed anymore.I hope the "personal view"(hackers) guys get into this.
Some have suggested that the avchd transformation of color space is improved by the chroma upsampling found in 5dtoRGB (free), if you still have the original footage perhaps you could give it a try and let us know.I would bet that the histogram goes off the right hand side on the raw footage.

Guy Smith December 20th, 2011 06:04 PM

Re: GH1 & GH2 color issues (skin tones)
 
<<The roxy video looks a little overexposed and the areas you mention look to me like what happens if you try to pull down over exposed highlights where there is little room to move because it is an 8 bit file.>>

There's an area on her forehead that's overexposed, but that's not the problem area in terms of green tint. The areas I notice are the mid-tones along her jawline and on her neck.

Her fiancee had the same issues in the same mid-tones. I wanted to see exactly what shade of green I was dealing with so I screen captured a frame of video, brought it into Photoshop, and sampled an 11x11 pixel area with the eyedropper tool. The result? The sampled color was flesh tone, not green. I created a box and filled it with this color and it did not look green at all.

At this point I'm seriously beginning to question my sanity. I had an opportunity to buy a brand new GH2 with 14-42 two weekends ago for $600 and passed on it because of the (apparent but possibly imagined) tint. Any idea what may be happening here?

Thanks for the heads-up on the GH2 firmware, I'll get it installed.

I'm not familiar with 5dtoRGB, what is it and where can I find it?

Colin Rowe December 20th, 2011 06:58 PM

Re: GH1 & GH2 color issues (skin tones)
 
Quote:

Originally Posted by Guy Smith (Post 1703864)

My personal GH1 has a couple of issues. It occasionally captures green still images, and when I say green, I mean completely green. This is after a manual white balance, and video recorded under the same controlled lighting and without changing settings or powering the camera off looks fine. This issue is random, and powering the camera Off/On will (eventually) solve the issue.

Just a thought. This exact same green problem cropped up on the EX1 back in the summer. I also used to get it on my 550D, always on bright sunny days. The problem was being over exposed whilst manually setting the white balance. Correct exposure on the white card solved the problem, well at least on my EX1 and 550D. It may be worth a try.

Guy Smith December 21st, 2011 02:56 PM

Re: GH1 & GH2 color issues (skin tones)
 
I don't think it's a WB or exposure issue as it only happens randomly, only with still images, and the effect is extreme, like only the green channel is being captured.

I do wonder though if over exposure might be the culprit on the GH2. I've found that setting the GH2 to Nostalgic or smooth greatly reduces the propensity to have a green cast to the mid-tones. Something for me to try and I appreciate the suggestion.

I uploaded a sample of my GH1 image issues here: https://skydrive.live.com/?cid=7c786...DD73245C94!509

Colin Rowe December 22nd, 2011 09:09 AM

Re: GH1 & GH2 color issues (skin tones)
 
That linked example is exactly what happens when white balance is executed manually, whilst over exposing on the white card. Try knocking down a stop or two when balancing, to see if it solves your problem.

Guy Smith December 23rd, 2011 12:26 PM

Re: GH1 & GH2 color issues (skin tones)
 
<<That linked example is exactly what happens when white balance is executed manually...>>

The white balance looked fine on the LCD and it also looked fine on the video that I captured (same settings) immediately after snapping the still image. Also, after cycling the power a couple of time it captured still images that looked like what I saw in the viewfinder - same settings.

I do appreciate your suggestion though and look forward to proving that pilot error is indeed the culprit.

Any thoughts on the desaturated areas in the video frame grabs?


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