BMCC 4K is Quad HD not 4K

[Alister Chapman]

And to think that once upon a time 4K used to mean 4K resolution, not 4K pixels. So very few of the 4K or Quad HD cameras can resolve anywhere near 4K. 4K pixels = 3.2K resolution on a good day.

But, then I'm also curious as to what 4K means in terms of the pixels on a TV screen. If it's 4K of individual pixels then the TV's won't show 4K of luminance resolution either. The TV/Monitor would need 4K x3, one of each R, G and B or around 25MP, so far I'm only seeing 8MP screens, but what does that mean, the TV manufacturers are deliberately vague. OLED technology looks very interesting as a single pixel can output R, G or B (although cheaper OLED's use 3 x white LED's each with a printed color filter above). About the only thing that is certain is that using todays definitions 4K is a bigger number than 2K.

[John Brawley]

It's all marketing speak isn't it.

There's another 4K camera maker out there that ended up going to a 5K camera so they could at least get 4K of recordable resolution on the screen. Their first effort could only get to a smidge over 3K on an actual resolution chart and 3.2K theoretically when taking the debayer in account. But it was recording a 4K file with that 3K worth of information.....so they got to say it was 4K.

Meanwhile, as pointed out, we've been projecting 1920 as 2K for a long time as well. HDCAM output 1920 but was pre-filtered to 1440 and had even less chroma sampling PLUS compression. Sony always fibbed about it too.

The whole chroma subsampling argument is also a bit misleading. For starters, it only applies to encoded video. Raw sensor data shouldn't be used in association with that kind of description, though it's a convenient leap to make.

I'm pretty sure we'll see a compressed RAW option on the 4K camera as well as the already announced ProRes 422. Personally, I'd rather see the 444 ProRes, not for 444, but for 12 Bit. Something that makes a bigger difference in my view to the end result.


jb

[Bob Hart]

I think I am developing morbid depression from future-shock in contemplating all this 4K stuff and lately have been beset by these weird throwback dreams of childhood, seeing kids at school playing hopscotch on a courtyard of green,green,red,blue repeating block patterns which flicker at about 25Hz. - Too much pixel-peeking I guess.

The scramble after being up with the crowd is like running a barefoot race over double-gees. It can be done but there is usually some pain involved in the process for the leader and everyone trying to play catch-up.

I'll leave my shortsight eyeglasses off at the cinema and then I won't know what I am missing if the camera artist has done his job. I won't then see the "calico look" or the repetitive swirl patterns from the artificial grain.

( I will have to speak to my local multiplex manager about that dreadful voice channel in Cinema 5. A handheld cop radio breaking squelch sounds better. )

In short, I guess I am rabbiting on about not being able to see the real art if one stands too close to the painting.

[Sareesh Sudhakaran]

Originally Posted by Bruce Schultz

I still like the 4K camera and feel that it is a great, inexpensive camera tool for TV broadcast work in Ultra/Quad HD, but I would be hesitant to promote it to any clients expecting cinema 4K resolution footage.

Anyone with a different take on this, please correct me or chime in.

We should welcome clients who won't tolerate a 6% difference, and can't be bothered with facts. We should tell them they are absolutely right, and charge them 60% more for a 'true' or 'legitimate' 4K camera.

What percentage of Blackmagic Design's market will actually produce work that will find a theatrical release? I am happy the BMCC 4K camera conforms to 4K TV - it is so easy to scale down to 1920x1080. And it shoots RAW in 12-bit. And I really don't see how anybody with a '4K' camera can make imagery better than this gem just by it being '4K'.

[Thomas Smet]

I guess some DV cameras were not SD because they shot 704 pixels instead of 720 pixels. Oh how I fooled my clients for years. Shame on me.

I'm sorry but 4k on a RED is still considered 4k regardless of the aspect ratio used. The BM is just limited to only one type of 4k. We used to shoot 16x9 4k on RED all the time.

Would an odd 6% anamorphic adapter help here? Honestly I don't think it is a big deal. Even film was shot at multiple aspect ratios. Even in a theater the amount of pillar boxing is so small I doubt anybody would notice.

[Jon Fairhurst]

FWIW, here is CEA's definition of Ultra High-Definition display characteristics:

TV/Video - CEA

A display system may be referred to as Ultra High-Definition if it meets the following minimum performance attributes:

Display Resolution—Has at least 8 million active pixels, with at least 3840 horizontally and at least 2160 vertically.
Aspect Ratio—The width to height ratio of the display’s native resolution is at least 16:9.
Processing—Has at least one digital input capable of carrying 3840x2160 resolution video and supports presentation of 3840x2160 resolution video from this input in a 3840x2160 or higher format. A qualifying display may not rely solely on up-scaling high-definition video content for presentation in a 3840x2160 or higher format.

[Daniel Epstein]

While we are putting links in. Here is Wikipedia's definition. Seems to justify Blackmagic's use of 4K even if it is not the same as 4K as defined by other organizations.

4K resolution - Wikipedia, the free encyclopedia

[Bruce Schultz]

So we have 3 items in play here with the BMD 4K Cinema camera;

1. Quad HD resolution at 3840 x 2160
2. Aspect ratio of (16 x 9) 1.78:1 vs 4K aspect of 1.90:1
3. 4:2:2 color space

None of these are to me a deal breaker, but of the three issues listed I am most concerned about the limited color space at 4:2:2 which would be OK for general green screen compositing but not for serious VFX work.

I started the thread to inform that these were the actual facts, not fanboy hopes and dreams. This camera will be a very handy small tool in any camera kit. I'm most curious though about the timeline for any raw capabilities and what those specs might end up being.

BTW, the Scarlet shoots it's motion 4K at Quad HD frame size 3840 x 2160 also. At least the inspector of any Scarlet 4K footage I've seen indicates this. Seems most post supervisors I've talked to lately like this frame size because of the easy 2:1 squeeze down to 1920 x 1080.

[David Heath]

Originally Posted by Daniel Epstein

While we are putting links in. Here is Wikipedia's definition. Seems to justify Blackmagic's use of 4K even if it is not the same as 4K as defined by other organizations.

4K resolution - Wikipedia, the free encyclopedia

I posted that link a little while ago. And there is no question that 3840x2160 is a form of 4k - it may be somewhat down to semantics but 3840x2160 seems to be taken to mean "television 4k", 4096x2160 "cinema 4k" and (as I said before) the difference is aspect ratio more than resolution.

Hence, I think Black Magic are completely justified in using "4k", but a "4K cinema camera" could be considered misleading.

Does it matter? In real life terms probably not that much. But then is it acceptable for a company to market a product as something it may not justifiably be described as? A bit like selling meat as organic, even if it isn't, then saying "so what? hardly any difference in taste, and just as good for you in health terms."

Originally Posted by Bruce Schultz

So we have 3 items in play here with the BMD 4K Cinema camera;

........
3. 4:2:2 color space

None of these are to me a deal breaker, but of the three issues listed I am most concerned about the limited color space at 4:2:2 which would be OK for general green screen compositing but not for serious VFX work.

As said before, irrelevant. The 4:2:2 figure applies to recording format. 4:2:2 is far better than what a 3840x2160 Bayer chip is capable of delivering, which in the same terminology is probably equivalent to about "3:2:0" Exactly the same applies to most of the 4k cameras on sale today, even such as the F5/55 - with 3840x2160 Bayer chips, they don't give what may be thought of as 4:4:4 4K. As Alister said earlier "About the only thing that is certain is that using todays definitions 4K is a bigger number than 2K"

[Douglas Call]

Originally Posted by David Heath

As said before, irrelevant. The 4:2:2 figure applies to recording format. 4:2:2 is far better than what a 3840x2160 Bayer chip is capable of delivering, which in the same terminology is probably equivalent to about "3:2:0" Exactly the same applies to most of the 4k cameras on sale today, even such as the F5/55 - with 3840x2160 Bayer chips, they don't give what may be thought of as 4:4:4 4K. As Alister said earlier "About the only thing that is certain is that using todays definitions 4K is a bigger number than 2K"

Does the Sony F65 have the capability to output true 4:4:4 4K in your opinion. I believe it has and 8K Sensor.

[Alister Chapman]

The F65 has 4K of green, 2K of blue and 2K of red in each row (the rows are arranged diagonally). So the nearest analogy to this at 4K would be 4:2:2. But it's not as simple as that. No real world object is ever pure green, pure blue etc so there is always some overlapping response in the other pixels. That's why a 4K bayer sensor which only has 2K of green, 1K red and 1K blue can resolve well over 2K, typically 3.2K. Given the right subject it could resolve higher. So the F65 is more than capable of filling a 4:2:2 output with data.

[Douglas Call]

Originally Posted by Alister Chapman

So the F65 is more than capable of filling a 4:2:2 output with data.

Alister thanks for that clarification. That would imply a definite benefit in capturing at 4:4:4, Now I need to get the workflow down for the F65 in the Adobe PP CS6 environment.

[David Heath]

Originally Posted by Alister Chapman

That's why a 4K bayer sensor which only has 2K of green, 1K red and 1K blue can resolve well over 2K, typically 3.2K.

I think it's important to add the clarification to that that what Alister describes (resolution of a 4k Bayer sensor to typically 3.2k) is true for LUMINANCE. Hence it will resolve white-black detail far better than if the same detail was red-black or blue-black, say. That's why it can never give a 4:4:4 output. That implies by definition equality of black-white and colour resolutions.

So the F65 is more than capable of filling a 4:2:2 output with data.

Hmmm. Not sure about that. The F65 is certainly likely to be capable of true 4k luminance resolution, and likewise for 2k chroma in the horizontal direction. (The requirement for 4:2:2) But vertically, I don't think so, We can take 4:2:2 to mean equal luminance/chrominance resolutions in the vertical direction and I don't see how the F65 can achieve that.

(For anyone interested in the F65 technology (Q67), there's a good link at Pixels vs. Pixels by The Sony Tech Guy . Looking at the initial diagram, the coloured squares represent corresponding coloured photosites, the white squares show how the output pixels are derived from them. So each pixel has it's green contributed by one unique green photosite, but the red and blue are an average of two each red and blue photosites diagonally either side of the green. That's why the chrominance resolution cannot be equivalent to luminance. To really get 4:4:4 4k, you would need either a 3 chip camera with 3 3840x2160 chips - unlikely to be practical - or something like a 40 megapixel Bayer chip with 7680x4320 photosites, processed on a 2x2 block basis. Practically, I doubt the improvement over Q67 would be worth it.)

[Dave Perry]

Don't forget that the Blackmagic 4K camera is not named a cinema camera. It's called Blackmagic Production Camera 4K. It really is semantics because the 2.5k camera IS called a cinema camera. Either way, we all agree that the final image is what matters most, not how it was achieved. Having said that, I can't wait for my Blackmagic Production Camera 4K to arrive!

[David Heath]

Originally Posted by Douglas Call

Does the Sony F65 have the capability to output true 4:4:4 4K in your opinion. I believe it has and 8K Sensor.

I've heard it referred to as an 8k sensor - but to do so requires a change of definition, and consequently I think it's misleading. Using the same terminology as "4k", "8k" implies 4x as many photosites, twice as many horizontally and twice as many vertically. (So if 4k is 3840x2160, 8k should be taken to mean 7680x4320, yes?)

Unfortunately, no - not here. The F65 sensor has TWICE as many photosites as such as the BlackMagic or the F5 etc - NOT 4 times as many. The link I referred to earlier makes it clear, and it is (as Alister has said) because the photosite rows are arranged on the diagonal. (See http://provideocoalition.com/sony/st...els_vs._pixels ) That makes it very difficult to give a simple AxB number. If you count 8k horizontally, the photosites will overlap, and without double counting, will mean it has 7680x2160.

It makes far more sense to refer to the F65 sensor just as a "16.5 megapixel" sensor. Using the terminology of "8k" would lead you to expect about 33 megapixels.