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Calling all colourists - Grade Panasonic GH4 4K ProRes next to Arri Alexa 2K ProRes


Andrew Reid
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I'm a bit worried sharing these, mainly because I'm paranoid I did something wrong on my end, regardless, I think it's good to share. First, I think the shot I used is a "worst case scenario" type of shot - because the shot itself is of a bland, bright sky that contains strong highlights and deep shadows (a real killer for 8-bit codecs as many of you know). Second, I think it reminds us that there is nothing like a true 10-bit codec, as opposed to 8-bit 4K being down-sampled to 10-bit 1080P (which in theory, works, but I think in reality it seems to fall apart somewhat - again, this may be a fault on my end). All in all, I think people shouldn't even begin to pass judgement on the GH4 until we see how it record in true 10-bit. I really hope that someone can show us true 10-bit out of the GH4 soon! I'd love to use the 10-bit 1080P at 60FPS that the GH4 is capable of to complement my Blackmagic Pocket Cinema Camera for slow-motion shots  :) 

Anyway, here are the shots I spoke about above. I simply imported Andrew's 4K ProRes file into Premiere Pro CS6, and did a light "Shadow/Highlight" recovery to see what kind of data I could get out of such an extreme shot - and guys, please remember that it is an extreme shot as it contains both strong highlights and deep shadows - I think any camera would struggle in this situation to be honest. However, the increase in colours that 10-bit brings would have definitely helped in the gradation I think. Also, I should point out - these are 8-bit JPEGS, however, I did render the shots as "Uncompressed 10-bit  YUV" (by way of Blackmagic's Premiere Pro rendering preset for Premiere CS6), and the results (in regards to the gradation) were the same. Anyway, enough of my ranting and raving, here are the shots:

ORIGINAL
33jljps.jpg

ATTEMPTED SHADOW/HIGHLIGHT RECOVERY
kb60eo.jpg
 

 

It is unlikely to be a problem with your methods.

 

I just think the only way to avoid this is raw.

 

Actually as luck would have it I took a GH4 JPEG and a raw still around the same time I took this 4K shot.

 

Try grading those the same and see if they hold up! http://www.eoshd.com/uploads/gh4-tower-stills-jpeg-raw.zip

 

The way to fix this issue is to record 4K via the HDMI port or the YAGH interface box. That is uncompressed and 10bit.

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All the GH4 footage i've seen seems to have incamera sharpening. Can this be turned off?

Also, it seems to have the same sharpening radius whether you're recording 4k ot 1080p which makes 1080p look even worse.

 

Copy.com doesn't apear to be working right now, but I look forward to playing with the footage as soon as it's back up. Thanks for sharing :)

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Maybe it depends on how people are doing the downsampling.

 

Using FFMPEG or just a simple scale in Premiere?

just scaling down and grading in After Effects... I'm not sure Premiere is as reliable as AE (yet it might be as both software are getting closer since "CC" and dynamic link) A few years ago all scaling operations done in Premiere was outrageous crap compared to AE. Morever AE as brand new bilinear filtering option (which I didn't use it this test)

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Hi all, it's been a while!

 

I'd like to do this, but the link appears to be dead...

 

I've been grading Alexa ProRess 4444 footage for an HSBC film this week so it'd be good to have a try with the GH4 now while I'm in the zone...

 

I wonder if Speedgrade will do it natively? I bet I'll have to transcode...

 

I suppose if I downscale transcode to 1080p in a 32-bit environment it's getting on for 444 anyhow? Is that right?

 

I'm a little rusty on sub-sampling.

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Guest Ebrahim Saadawi

Bloody hell! From initial observations: these files grade better than the 1Dc's MJPEGS! Utterly shocked by the image!
(And I've been skeptic about this gh4 hype- convert now and ordering 1 8) ) 

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Bloody hell! From initial observations: these files grade better than the 1Dc's MJPEGS! Utterly shocked by the image!
(And I've been skeptic about this gh4 hype- convert now and ordering 1 8) ) 

 

I agree. The GH4 looks better than most of what I've seen from the 1DC. 

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I agree. The GH4 looks better than most of what I've seen from the 1DC. 

 

I've used the 1DC on pro shoots and I didn't like it. The GH4 (for video) does so much more for less, shooters might as well spend the money on lenses than an expensive body!

 

The biggest issue I found with the 1DC is focusing a 4k image on full frame, its very challenging compared to other cameras. 

 

The only reason I can see a video shooter needing to buy a 1DC is if they need 4k images AND need the power behind the stills capture. 

 

Looking forward to having a rummage around 4k 10bit files! (and 1080p of course!)

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Guest Ebrahim Saadawi

Let's not forget that productions and money have already been made with the 1DC over the past years even before the GH4 ever existed. The 1DC is old by technology terms. It came in an age where we couldn't believe 4K can be acquired by a DSLR body. It was the first one to introduce this capability, a capability that will drive the next generation of filmmaking and improve the quality termendously. So it deserves some respect I say. First 4K TV ever made cost 200K, and now they're 600$.

But nontheless, from these samples and my familiarity with the 1Dc motion JPEGS, hese files truly do look more gradeable. More detail too!

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Actually didn't Red have 4K with the Scarlet around 1D C prices way before Canon launched their 1D C circa $13k?

 

And it isn't old technology. The 1D C is based on the 1D X and that is bang up to date. There's no newer or better Canon tech out there.

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Guest Ebrahim Saadawi

Actually the Dalsa is the first 4K camera if we look at this way, you get my point. Anyway let's just agree this GH4 does blows out every other camera in the market right now. This is a kind of camera that even affects the Red and Arri- class markets. Just like the 5D2 did. I think it's that big. Stupidly excited for the low-light test! :D 

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It's not so much about the age as it's about how you turn all those pixels into video and Panasonic knows how to do that brilliantly. The full readout, double the speed because of 4K to avoid rolling shutter, the 4:2:0 coming AFTER the 4:2:2, these are little things that increase the IQ dramatically it seems.

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Okay, for anyone that already feels their head exploding over 4k to 2k bit depth issue, please do NOT click this link:

 

https://vimeo.com/90836503

 

This is a quick 3d render done initially at high settings, 32bit exr. Then saved as 12, 10 and 8 bit uncompressed dpx @ 4k. Then those renders are reformatted to HD 1080 in a float comp and given a gamma curve nobody in their right mind would ever do. 

 

I wanted to see for myself how much artifacts improve with a  50% 4k resize in a 32bit comp. Short answer, not much.

 

But, I don't want to be a buzzkill.. the GH4 looks awesome and we're getting one here...

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If you're trying to downsample GH4 footage to 2K RGB, this isn't really the way to do it.

 

The proper way is to do the RGB downsample on the original H.264 YCbCr data before it's been meddled with by Compressor or AME or anything else. Posting ProRes files doesn't help because the the original 4:2:0 data was screwed up when it was transcoded to 4:2:2. Furthermore, we're working with a second generation copy, which is a no-no.

 

Post the original files from the camera. I'll have a look and see if I can whip up an app that will do what everyone wants.

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