GH3 m43rumours Panasonic GH4: can it do 4:4:4 at 1080p?

You can test this now with the GH2 or GH4. Well in fact any camera that shoots 4:2:0.

Take your 1080p video and down convert in a program that handles higher than 8bit internal processing. For example After Effects. Down convert to 960x540 and you will have a video with 10bit precision and 4:4:4 color. Really is amazing. Also cleans up a lot of noise and compression artifacts. Now just imagine the exact same process but ending up with 1920x1080 instead of 960x540.

If you really want to see how a 4k video can work like this from a 4k sensor than take a still image from the GH2/GH3 and crop it to 3840x2160. Then render that still as a 4k video at 100mbps. This will turn it into a video encoded at 4:2:0 similar to how the 4k video will look from the GH4. It is similar because the 4k mode will crop the sensor as well so basically you end up with a similar look. You can then load that video into After Effects and repeat the process above to get a 4:4:4 10bit 1080p video. Granted it doesn't move but you will see how the pixels clean up and result in very high quality HD video.
 
The answer here is "maybe". It depends on what you think the question is.

If the question is: "can you convert a 3840x2160 4:2:0 image into a 1920x1080 4:4:4 image", then the answer is yes. In 4:2:0, color is sampled at the rate of one color sample for each 2x2 block of pixels. So, in essence you have a 3840x2160 grid of brightness information, and a 1920x1080 grid of color information. Each pixel of color information is applied to a 2x2 block of brightness. So, yes, when you downconvert, you should end up with 1920x1080 with each pixel having its own color information, thus becoming 1920x1080 4:4:4.

But -- if the question is "will the GH4 deliver an image that's every bit as sharp as a top-end 1920x1080 4:4:4 camera would", the answer is -- maybe, maybe not. We don't know, until it's been tested. It depends on how sharp the 4K footage is to start with. To see what I mean, consider the HVX200 -- it delivers about 1440 x 810 worth of image sharpness in its 1920x1080 recording mode. That's about the same as a Canon 5D or 7D; none of them are nearly as sharp as, for example, an F55. They're all "1080p", but only the F55 is truly "sharp" enough. So -- the question is, how sharp is the GH4? If it delivers a true honest-to-goodness 4K sharpness level that rivals an F55, then yes, I would say 1080p 4:4:4 downconversion would be a very real possibility. But if it's not all that sharp, then you can't expect the downconversion to be as sharp either.

What I'm saying is -- the 5D, 7D, and HVX all record 1080p, but their images are not as detailed as 1080p is capable of. So the GH4 may record 4K, but if its images aren't as detailed as 4K is capable of, then the downconversion won't be as detailed as 1080p 4:4:4 would be capable of. If that makes sense. But regardless, it should be very, very good 1080p. It may or may not be ultra sharp with full 4:4:4 color sampling, but it should be a darn sight better than any existing DSLR's 1080p, and may even rival the sharpness of dedicated 1080p video cameras.
 
Barry_Green said:
The answer here is "maybe". It depends on what you think the question is.

If the question is: "can you convert a 3840x2160 4:2:0 image into a 1920x1080 4:4:4 image", then the answer is yes. In 4:2:0, color is sampled at the rate of one color sample for each 2x2 block of pixels. So, in essence you have a 3840x2160 grid of brightness information, and a 1920x1080 grid of color information. Each pixel of color information is applied to a 2x2 block of brightness. So, yes, when you downconvert, you should end up with 1920x1080 with each pixel having its own color information, thus becoming 1920x1080 4:4:4.

But -- if the question is "will the GH4 deliver an image that's every bit as sharp as a top-end 1920x1080 4:4:4 camera would", the answer is -- maybe, maybe not. We don't know, until it's been tested. It depends on how sharp the 4K footage is to start with. To see what I mean, consider the HVX200 -- it delivers about 1440 x 810 worth of image sharpness in its 1920x1080 recording mode. That's about the same as a Canon 5D or 7D; none of them are nearly as sharp as, for example, an F55. They're all "1080p", but only the F55 is truly "sharp" enough. So -- the question is, how sharp is the GH4? If it delivers a true honest-to-goodness 4K sharpness level that rivals an F55, then yes, I would say 1080p 4:4:4 downconversion would be a very real possibility. But if it's not all that sharp, then you can't expect the downconversion to be as sharp either.

What I'm saying is -- the 5D, 7D, and HVX all record 1080p, but their images are not as detailed as 1080p is capable of. So the GH4 may record 4K, but if its images aren't as detailed as 4K is capable of, then the downconversion won't be as detailed as 1080p 4:4:4 would be capable of. If that makes sense. But regardless, it should be very, very good 1080p. It may or may not be ultra sharp with full 4:4:4 color sampling, but it should be a darn sight better than any existing DSLR's 1080p, and may even rival the sharpness of dedicated 1080p video cameras.
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Wouldn't that be true for stills then as well. To say any of the GH cameras are not detailed enough for 4k also means they are horrible for stills which is not true. They take very good detailed stills at higher than 4k resolution. Since the GH4 will crop the sensor to record 4k it is likely the 4k video would be as good as the stills quality which should be very detailed. Unless they seriously take a giant step backwards in terms of sensor quality. It is my understanding the new GH4 sensor is supposed to be even better for stills so I would doubt the 4k video would be bad.

Isn't grabbing a 4k chunk in a 1:1 ratio the same as grabbing a high quality still from the full sensor at 1:1?
 
You're making some assumptions there that aren't what I said or meant. For example:
To say any of the GH cameras are not detailed enough for 4k also means they are horrible for stills which is not true
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First of all, I never said the GH wouldn't be detailed enough for 4K. All I said is -- we have to see how it performs. Second, I never said anything about its stills performance. But you're linking the two, which is not necessarily a wise thing to do. Look at the 5D, it has tremendous stills performance and (by my standards) awful video performance. How the sensor is read out is not necessarily the same, between stills and video. Have you seen any hybrid camera where the stills look exactly the same as a single frame of video? I haven't.

I never said the video quality "would be bad." I am not expecting it to be bad. I am expecting it to be superb. All I was saying is -- we don't know how detailed it will be, and until we do know, any postulations or assumptions about it are exactly that -- assumptions. We won't know until we get it in our hands and test it.


Isn't grabbing a 4k chunk in a 1:1 ratio the same as grabbing a high quality still from the full sensor at 1:1?
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Maybe, maybe not. Depends on how they're reading it out. It potentially could be, it seems reasonable that it might be, but it might not be. The slower rate of stills might provide an opportunity to do some additional processing on it, where a video frame might have to be quickly grabbed just to get on to the next one.

Simple question to answer though; as soon as a GH4 shows up, we can test that.
 
From my point of view, the interesting thing to see will be how much difference there is between 10 bit 4:2:2 HD from the hdmi and 4K footage down converted to HD. The most exciting thing for me is not the 4K at all, but the new cine profiles, the new high bit rates and that high quality 10 bit output.
 
Thomas Smet said:
Isn't grabbing a 4k chunk in a 1:1 ratio the same as grabbing a high quality still from the full sensor at 1:1?
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Another current basis for comparison/speculation you could use is: ETC mode video (on a GH2/3) vs a still photo cropped to 1920x1080 (since the GH4 essentially implements a new 4k ETC mode).
 
BitMaestro said:
Another current basis for comparison/speculation you could use is: ETC mode video (on a GH2/3) vs a still photo cropped to 1920x1080 (since the GH4 essentially implements a new 4k ETC mode).
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Except in that case you are stuck with a 1:1 pixel readout at 1080p. Some artifacts do go away with ETC mode but you gain others in the process. Less detail a lot more noise and so forth. The advantage to a 1:1 readout for 4k is that it can then be scaled down to HD in post which will bring back that detail and reduce the native noise of the sensor. Shooting 4k on the GH4 and down converting to HD should be vastly superior to ETC on the GH3.
 
Barry_Green said:
You're making some assumptions there that aren't what I said or meant. For example:


First of all, I never said the GH wouldn't be detailed enough for 4K. All I said is -- we have to see how it performs. Second, I never said anything about its stills performance. But you're linking the two, which is not necessarily a wise thing to do. Look at the 5D, it has tremendous stills performance and (by my standards) awful video performance. How the sensor is read out is not necessarily the same, between stills and video. Have you seen any hybrid camera where the stills look exactly the same as a single frame of video? I haven't.

I never said the video quality "would be bad." I am not expecting it to be bad. I am expecting it to be superb. All I was saying is -- we don't know how detailed it will be, and until we do know, any postulations or assumptions about it are exactly that -- assumptions. We won't know until we get it in our hands and test it.



Maybe, maybe not. Depends on how they're reading it out. It potentially could be, it seems reasonable that it might be, but it might not be. The slower rate of stills might provide an opportunity to do some additional processing on it, where a video frame might have to be quickly grabbed just to get on to the next one.

Simple question to answer though; as soon as a GH4 shows up, we can test that.
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Didn't mean anything by it Barry. Was just partially asking how you felt the detail would hold up if it was similar to the stills capability.

I agree we don't know for sure. The one thing I do believe is that it should look better. By how much is debatable. Maybe it will not beat the best native 4:4:4 camera in the world but I do feel for budget people (And even a lot of pros) the 4:4:4 HD we will get will be better than most of the stuff in this price range or even much higher in price. 4:4:4 HD is pretty unheard of for most people and even if the detail isn't great should be better than some recent native 1080p bayer sensor cameras.
 
Thomas Smet said:
Shooting 4k on the GH4 and down converting to HD should be vastly superior to ETC on the GH3.
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Yes. Obviously 4K down converted to HD should be superior to "regular" HD. I was pointing out that, according to the theory that 4k video displayed at 4k (not down coverted) would have a similar level of detail as a still photo cropped to 3840x2160, an ETC mode video should also have a similar level of detail as a still photo cropped down to 1920x1080.
 
Hoping Barry might pipe in as I wrap my head around the Gh4... Can anyone clarify some GH4-ness for me? Without the YAGHE but with these supposed next-gen cards, and with, say a Ninja2 via HDMI... what do we have?

As I understand it, 1080 at usual frame rates, to new-class internal cards: 8 bit, but a bit rate of 100 or 200? Sort of a quantum leap from AVCHD & current DSLRs IQ?

1080 at usual rates to Ninja/etc at 10 bit (444? 422?) & even higher data rate?

4k to internal card at 8 bit - does the data rate/quality compare to 1080 in this case? Or is there a quality drop to capture this much data to card?

4k to recorder - Can a Ninja2 handle this? And what's the image improvement with a recorder? 10 bit? Or are we waiting for HDMI-capabale 4K recorders, in the sub $1k zone ("affordable")?

High frame rates - 96 fps @ 1080? What's the tradeoff to internal card with this much data? Lower bit rate?

High frame rate to external - again, can, say Ninja2 or current affordable recorders handle this? and what do you gain externally in bit depth or data rate?

GH4 & a recorder could really be the commercial/beauty cam I've been hoping for vs/ Epic rental...(yeah I know it's no Epic, but a "you-own-it" lightweight & simple camera could allow me to deliver more creative ideas to mid-level clients - compositing 4K for 1080 output and very good 1080 slowmo.)
 
Michael Carter said:
1080 at usual rates to Ninja/etc at 10 bit (444? 422?) & even higher data rate?
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Option 1: Recording to Both Card + Output to HDMI - you will get 8Bit 422 (to both)
Option 2: 'Creative Mode' Output only to the HDMI - you will get 10 bit 422

On both you would specify if you want 1080p or 4k to the HDMI - if you set 4k, the ninja wouldn't accept it.

As to bitrate - I presume its not capped - but 1080p ALL-i to the internal card is now 200Mbps.

Michael Carter said:
4k to recorder - Can a Ninja2 handle this? And what's the image improvement with a recorder? 10 bit? Or are we waiting for HDMI-capabale 4K recorders, in the sub $1k zone ("affordable")?
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Ninja2 can only handle max 1080p 10bit 422 (and only at 29.97fps/30fps)
 
Barry_Green said:
You're making some assumptions there that aren't what I said or meant. For example:


First of all, I never said the GH wouldn't be detailed enough for 4K. All I said is -- we have to see how it performs. Second, I never said anything about its stills performance. But you're linking the two, which is not necessarily a wise thing to do. Look at the 5D, it has tremendous stills performance and (by my standards) awful video performance. How the sensor is read out is not necessarily the same, between stills and video. Have you seen any hybrid camera where the stills look exactly the same as a single frame of video? I haven't.
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However Panasonic in this category is miles ahead of Canon as far as hybrid cameras. Starting with GH2, Panasonic video performance is far better implemented then any Canon out there. In this case it will be safe to assume GH4 will be better then Canon.
 
Jim Simon said:
Wouldn't that depend on the software doing the downconverting?
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Not really. The down conversion method may affect the overall quality of the 4:4:4 video but it is still 4:4:4. The ratio of luma to chroma samples is what matters. The down conversion method will determine how clean each of those pixels are. Even nearest neighbor would leave you with 4:4:4. Granted an ugly 4:4:4 but it would still be 4:4:4.

You can test this now by down converting 1080p material to 960x540.
 
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