Two questions about downscaling 4K

[Stokestack]

I keep asking these in relevant threads, but so far no answers. I'd like to have one set of lenses and have the 35mm DOF regardless of what my stored image size is. So...

1. Is it technically possible to scale raw images (hopefully in camera) and keep them "raw" (in other words, keep their raw latitude)? If there are R, G, and B photosites on the sensor, isn't it possible to resample and merge their values just as you would with pixels in a non-raw image? Then store them in a file that looks (in terms of data layout) like a 2K raw file?

2. Why is the RGB storage only 4:2:2? This becomes a bigger deal if the answer to #1 is no, leaving 1080P RGB our only 4K-to-smaller scaling option.

Thanks!

[Rob Lohman]

1. this is not a feature for now. Who knows what will happen in the future with some Graeme magic, but not right now. Shoot 4K and downsample that or shoot 1920 x 1080 RGB which is fairly close to 2K.

2. where did you get this? RGB is "4:4:4", there is no real "4:2:2" format for RGB.

So when you shoot 1920 x 1080 or 1280 x 720 in RGB you will get the full resolution and full sampling!

[Jim Arthurs]

So when you shoot 1920 x 1080 or 1280 x 720 in RGB you will get the full resolution and full sampling!

One important thing to remember for those who are only dreaming of mega-rez 4K... the 1280 by 720 (the other HD) will be SPECTACULAR. Without question, the best in class. And plenty clients want it.

Remember, this is not DVCPRO 100 720 which is an anemic 960 by 720, or exactly 2X SD resolution.

So, since 720p is a viable format, RED will give the worlds best 720p... full raster, and massively downsampled in a bullet-proof 4:4:4. There's plenty of life and demand for 720p, and just think of the long record times on one RED drive...

[Chris Kenny]

Yes, there's going to be a big difference between a lot of the 720p out there now (4:2:2, DCT compressed, 8-bit, 960x720, often created using barely-HD sensors, etc.) and what RED will produce (4:4:4, wavelet compressed, 12-bit, 1280x720, and massively oversampled).

[GlennChan]

Other cameras actually have higher bit-depth A-->Ds behind them than Red (i.e. 14-bit). Compare that to Red's 12-bit A-->D. So in particular numbers, other cameras might have an edge over Red.

2- Alan Roberts has an intriguing post over at dvdoctor.net, claiming the HDX900 has 12 *measured* stops of exposure range. And he's credible, doesn't work for Panny, and definitely knows his stuff. 12 stops is slightly greater than Red (although Red's exposure range might go up once you downsample??????).

http://forums.dvdoctor.net/showthrea...ops#post279767

Not saying that it's necessarily better, but definitely interesting.

[Laco Zamba]

Compare that to Red's 12-bit A-->D

Is it true?
I don't think so.

[Jeff Kilgroe]

And since we're on the subject of best in class 720p...

Can someone clarify for me, is 720p downsampled from the full 4K sensor size like 1080p is? I would assume it is, so we get the benefits of the full sensor size and DOF. Also is it possible to shoot 720p using a windowed sensor area so we can have frame rates in excess of 60fps? In other words, could the 2K windowed sensor area be used to record 720p @ 120fps on camera?

I've seen such things mentioned in various threads here, but have not seen actual clarification of this. 1080p downsampled from the full 4K sensor size and recorded as RGB on camera is probably what I will use for most of my real-world work for clients. It just fits like a glove and a lot of them are starting to ask about BluRay/HD-DVD. But if I could also shoot a windowed 2K area at up to 120fps and record it downsampled to 720p RGB, that would be great.

[Jeff Kilgroe]

OK, I'm assuming what I asked about can all be done based on the format options chart at RED.COM. So correct me if I'm wrong.

[Rob Lohman]

Yes, that should be how it works Jeff.

[Chris Gearhart]

Other cameras actually have higher bit-depth A-->Ds behind them than Red (i.e. 14-bit).

As for 14 bit color depth of other cameras--and I am not up on what cameras are 14, but just taking your statement--I wonder at what cost, SNR-wise? Is their sensor really capable of pushing that much latitude? And if they are not getting 13 or 14 stops, what is the benefit to storing/transmitting that much data? I wonder if that isn't a spec in search of a benefit. I am speaking from complete ignorance, however. :weight_lift:

12 stops is slightly greater than Red

I wouldn't count on that. Graeme has been getting wacky-compulsive in getting the full 12 stops out of the 12 bit space. His posts are very . . . suggestive. As always, everything is subject to change, count on it (including this sentence).