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Panasonic GH4 vs BlackMagic Cinema Camera Green Screen Chroma Key Comparision

Paul Shillito Cameras, Editing / VFX 4 Comments

[Update 4th July 2014]

Having just seen that this article has been mentioned in nofilmschool.com, thanks guys 🙂 , there have been a few comments saying that its not a fair comparison, so I’ll say here what I should have said in hindsight in the video.

The video is a comparison as much of two similarly priced cameras as it is about the difference in resolution and which types of codec used to produce the footage is the best for green screen/ chroma key work for the average amateur vidiographer, after all these are cameras aimed at the amateur / Semi Pro market. Professionals will be going for RED’s, Arri’s, Pro Sony’s etc etc with much larger budgets.

There are some saying that the keying technique is not in keeping with the lastest industry techniques and that will affect the keys produced. Yes, again that is partially correct but I was showing what the average person with access to Adobe affects and premier might expect, not what a professional VFX artist / compositor would do with much more knowledge and expensive software. This is a quick and simple comparison showing a simple and very widely used keying techniques that almost anyone can do with out using more advanced techniques like core mattes / multiple mattes.

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Two cameras, the 4K Panasonic GH4 with a standard compressed output and the 2.5K uncompressed Blackmagic Cinema Camera but which one will be the best for green screen / chroma key work.

Normally when working with chroma key or green/blue screen you would look to use an very high quality output like cinemaDNG RAW or ProRes 4:2:2 but can a 4K camera like the Panasonic GH4 with a compressed output work as well.

In this video I do a comparison test in a green screen setup to see which one works the best and show the results in Adobe After effects and Adobe Premier Pro CS6.

Link to Youtube : https://www.youtube.com/watch?v=-bUUNL6Zhvg

 

{Video Transcript}

Two cameras, one green screen Panasonic, GH4 and The Blackmagic Cinema Camera but which one of these two is going to be the best when it comes to chroma key work.

Now if you know anything about chroma key or green screen work you know that once you get your green screen sorted out the next thing is your camera. We’ve got the compressed version output 4K GH4 which records H.264 and chroma subsampling of 4:2:0 not normally the best combination for producing green screen work.

Then we’ve got the Blackmagic Cinema Camera 2.5K cinemaDNG RAW with no compression, no artifacting, no subsampling or ProRes 4:2:2 sub sampling but still no compression. So a lower resolution but no compression camera and a high-resolution compressed camera.

Now to help me i have my erstwhile assistant who as we can see is having a really bad hair day at the moment but seriously hair is one of the more difficult things to actually do a good chroma key on and even if you get a bad background badly lit or your camera cannot handle the actual quality what the actual image is then you can end up losing a lot of detail in the actual chroma keyed output.

So what we’ll do is we’ll actually film this on a rotating stand to have a full 360 degree view will do it in 4K compressed from the Panasonic GH4 and we do in 2.5K cinemaDNG RAW and also ProRes 4:2:2 in 1920 x 1080 from the Blackmagic Cinema Camera.

We’ll put this into after affects and we’ll see what the difference is are between the two cameras and effectively the three types a format

OK, we now in After effects and we got our three piece’s a footage, we’ve got the ProRes, the RAW and the 4k from the Panasonic GH4 in respective comp’s here. As we can see we got this equivalent to probably a mid body or a long body shot here if this was up here the head will be a bit further up but this is a sort of the distance which we are working at for normal sort of person to be green screen onto a background.

First thing we need to do is to mask of this background here go do that by cropping off using the pen tool, a mask area so we can just work on this and get rid of that background at the moment now then, all you need to do now pick background in key light, here we are we’ll just click on that and their way up straight away we’ve got a pretty good key and we haven’t really done anything yet.

What we need to do is actually to refine this a bit now and look at this with the screen matte and see and see what we’ve actually got. We can that’s it is not totally back and white should be completely white here completely back around the edge here so what we need to do is to tweak this although actually don’t need to worry about anything outside but this box here.

So we dont need to worry about what’s going on in here so if we clip this back we only need push it back so its black here. We are about 13 at the moment the fact if we go to status it’ll give us an enhanced version of this so we can actually see it a little bit better will push out so it completely black here and now we want to make this completely white and in the gray but he’s gonna be transparent semi-transparent area around the edges of the hair.

So we’ll pull this in, this is clipping white we don’t do this the face will become semi-transparent and you’ll see things partially showing through it so we’ll pull this back to about there, these obviously the more we pull this back more which pushes it down I’ll show you in a minute what happens.

Now if we combine result me go back to here and that looks quite good now if we put it on a white background we can see now if we turn this on and off we can see where losing our detail in fact hair looks thicker if anything on the keyed out version than it does on the original and that is down to this. If you watch this, this is affecting the white clip which you can see she’s getting lighter here it’s getting lighter because we are letting in more transparency through obviously we need this to block that out and the more we block this back the thicker hair becomes and this is where it starts sort of not look quite so realistic when you have got this thin hair here and you losing the detail but it’s just something you’ve just got to put up with.

Really you gonna be around about there that’s what we were looking on our status something about there we go any further back miss why we’re gonna start getting the transparent face again so we are back to that and that’s come out quite well. So now we’ll do the same on the RAW again we’ll mask this off there, there, there, and there turn off the background pick our color, zap.

There we go and now notice we got a bit of a frizz around the edge, it look s highlighted it looks a bit of the odd looking there and that is really down to this pre- multiplied output and what he’s doing is, where there is semi transparent part is now is multiplying the color of the brightness of the pixels right on the edge with the alpha so they are now darker as the alpha gets more transparent in fact this is left on by default there are left at full brightness and that this adds this highlighted edge on things which you might want, you might not want, I find that if I’m going to put this on this background and when it actually turning it’ll look more distracting than if it’s taken off, it looks a bit better.

There with that detail and as you can see that’s looking quite good I fact on here I’ve also got a simple choker and what that’s doing is you see that it’s pulling it in slightly more as well so it’s getting rid of that little frizzy effect It can start to look at bit sizzly easily as if things turn around and you don’t see it until you actually looking at it in motion and you cant really see it here it you get this sizzling effect right on the edges there.

So too reduce that I’ve got a simple choker and pulling it in just over half pixel nice actually looking quite good on that one and only white Now thats RAW now obviously we got more detail here because this is 2400 pixels and so we’ve got more pixels to build it up see the actual hair.

Now if we come onto the Panasonic GH4 4k version will say that we’ve got more details still and even with the compressed output we not losing really a lot of detail if we pull in here and look at this edge i’m looking individual hairs now and bear in mind we are still pulled out here so she’s any making up a small area of the screen but we can pull into literally see individual hairs.

So lets see how this is going to key out so again we’ll mask this area of and will go there, there apply the background colour and we are a little bit light on there so we’ll take that off the edge there, now we’ll look at our screen matte yes again we need to pull this in and make that the blacks blacker.

We need to make the whites as white as possible quick look at the status how that looking and pull black in little bit more there we are and there we are and as you can see we got more detail in the actual hair you see the highlighting on this artificial hair as well showing up quite well.

If we put it on the background again we’ve got quite a good there is looking nice near the edge looks a little bit artificial the edges there but it’s not too bad and have we got a choker on here yea, we go to choker on here which is pulling it in very slightly see that difference there you can just see it appearing In and Out as I’m pulling in by half pixel and that’s what it needs to do to make that so now we’ve got that we put it on white again we can see and that’s come out quite good so let’s now render these off into some different comps and I will put them in to Adobe Premiere and then we can see the things running in real time and compare the three altogether.

So we’ve rendered off each of out respective comps into an individual files, there are three files here we’ve got the Pro is HD which is on the left which is at 1920 by 1080 Full HD resolution then the cinema DNG RAW version which was two-and-a-half K or 2.4 K and in the center and then we got the Panasonic GH4 4K which is the fully compressed version which is the H.264 output and chroma sub sampling of 4:2:0 so this is actually the worst sort of compression version and these the one in the center will be the best because there is no compression at all and then there’s just the sub sampling on the ProRes HD.

But actually if we look at this straight away we can see that the ProRes has actually come out really rather well actually the some nice detail in in the hair here and in the edges it’s not quite as detailed in the face and in hair as it is in the 2.5K but when we look at the 4k you can see there’s a lot more detail in the face, the eyes look clearer, the mouth.

Then you’ve got the hairs here and if we actually move it around which we can do here if we look at this curl of hair here, this one and you watch it turns and then look at the same in the other one here this is the centre it doesn’t so shine as much and then in the ProRes again it looks quite sort of dull in comparison.

This one has definitely more of a shine to it and it’s on with the rest to the hair it picked up these little shining details more now this is because we we’ve got more pixels at work in here over obviously these are all scaled-down from their respective sizes to full HD.

The source material was higher resolution so the end result gonna look slightly better even if they are still the same Resolution so we can see that the ProRes is lowest resolution of all of them but its actually got still quite that good

edge detail and the edge detail and this is what we are interested in when we are doing Chroma Key so thats done very well there the cinemaDNG RAW again has done it but I know it’s on this if we run it and let it go it does have have this sizzly effect around the edges which I was talking about before you can see there it’s i think it where the key is keying and then losing the key and in and out slightly so it gives it this sort of sizzling effect as if it there and not there.

Then on the actual 4K around the edge it’s really well smooth finish there isn’t a lot of sizzling going on its nice and semi-transparent it’s not quite as defined as the ProRes version but the very fine details here have got a little bit so mushy in there not and i dont know if thats the compression working on that very fine detail.

We are scaled down here and as i say we have a choker on here on the actual alpha here which pulls in the Alpha all the way around and takes off some of the fine detail on all of them so we could actually of brought back out and left in there but I think then we end up with a small sizzling effect in getting the very fine edge as we do with here so I think probably best to pull this in a little bit if you don’t know what the original would look like you would say, yes they look very good but because we know what the original look like we say yes well I can see where it’s been pulled in a little bit it’s not quite as it should be there.

So if we now look at it on a different background and we look at this on a studio background now because you have a darker background it looks very well integrated into this background.

So i would say we’ve got pretty good Key on all of these and really then it’s down to the detail that we are carrying over in the actual image itself and really the 4K does show this up this up as the best so really we’ve got the lowest in theory quality image, but because it’s the highest resolution it’s giving us the best image here in the 4k, it also the smallest file size: so really I think we can say that the winner this as far as overall usability and the quality of the look goes is the 4K GH4.

So the cinemaDNG and the ProRes which both come from the Blackmagic camera are almost redundant now compared to what we’ve got coming out 4K Panasonic GH4 can I this is exceedingly good and also be colour grading if you look at the colour grading on it it’s pretty damn good as well these very nice.

Don’t forget that its actually half its size this could be scaled up to 100 percent and twice as big as this and you’ve still got all detail in we can scale this one up by 20 percent and this one if we scale it up anymore will start losing detail.

So the conclusion I can draw from this is that the Panasonic GH4 4K standard output will make a very good consumer grade camera for chroma Key or green screen work.

The compressed high-resolution output of this camera trumps the uncompression lower resolution of the Blackmagic cameras and with the added benefit a much smaller file sizes will have a bigger impact on your computer and your long-term storage the only reason I can say for using the Blackmagic RAW output is if you gonna be doing a lot of color grading.

There is also the option of the Blackmagic 4K camera but they are still have issues with that. The Panasonic GH4 has a lot more usability options and you can also get a ProRess 4:2:2 output from it if you use a separate recorder but as we’ve seen standard 4k compressed output will do a very good job for most situations.

I hope that you found this video useful and if you did them please give it a thumbs up and subscribe to our video alchemy channel and share it with someone who you think might benefit from it don’t forget to hop on over to Video-Alchemy.com and join our newsletter my name’s Paul Shillito and this has been a Video Alchemy production so until next time byeee

Comments 4

  1. fanis

    hi there.

    i am opening a small production company in new york
    and would love your advice when it comes to building the right green screen.

    I would love your advice on getting the right setup.
    Let me know if you’ve got 5 minutes to shoot some question.

    Where are you located?

    Best
    Fanis
    PS VIDEOS ARE AMAZING

    1. Post
      Author
  2. Brad Simon

    I am very interested in the Panasonic GH4, but would love to first play with the video footage myself. Is there anywhere I can download the 4K green screen footage you shot with the Panasonic GH4 so I can play with it on my end?

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