Color Compression with Redcode Raw

[Musashi]

Hey,

well long story, our company is just thinking about jumping on the "HD Train" but is still hesitating. Iam currently the responsible one for the main Information about the new workflow with HD or even 4k material.

And okay, i took quite a while to get all the information that i need, but after a shot time i was quite sure, that Red is the one camera, that will fit our needs.
I'm allready quite exited about when we will order it, but first i would like to know some details i never found on the page...

Okay so the actual Datarate of 4k Redcode RAW Footage is actually about 30MB/s.
But we gonna work with a lot of keying... So uncompressed Footage would be desireable. But i think capturing a ~880MB/s für uncompressed 2k footage would blow our credit card in a few shots ;)

So to get the point: At what level is the Color compressed in Redcode Raw Footage? I know i can choose between 4:2:2 or 4:4:4 via Dual HD-SDI, but i never found information regarding Color Compression with RedCode Raw or RGB!


Anyone can reveal the fog in this mistery?

Musashi

[Stephen Gentle]

REDCODE RAW is 4:4:4. It's also excellent for keying, and I highly doubt that you'll ever need to pull uncompressed data off the camera, unless you want 120fps @ 2K. Some people have suggested that REDCODE RAW 4K will give you a better key than uncompressed 2K.

There are some greenscreen grabs from a really old RED prototype here. They're all a one click key in After Effects with Keylight form me. Apparently REDCODE has improved significantly since then too.

-Stephen

[Musashi]

4:4:4?
This seems nearly impossible to me, since we have a datarate of ~30MB/s.
This is only slightly more than the compression of a DV Tape, and Red contains ~16 times more Pixel than DV, even no color compression...

Can someone give me the hint, where the fault in my thoughts is?

Well if there is none, maybe the RED Team should next answer questions like "What was first - Chicken or egg" or "What is the sense of life", they seem to be the only one who are capaple of solving big problems

Musashi

[Lucas Wilson]

4:4:4?
This seems nearly impossible to me, since we have a datarate of ~30MB/s.
This is only slightly more than the compression of a DV Tape, and Red contains ~16 times more Pixel than DV, even no color compression...

Can someone give me the hint, where the fault in my thoughts is?

Hi Musashi,

I think your main misconception was in your first e-mail - 880MB/s.

The RAW data that will come off the RED ONE is only 323 MB/s. It is raw Bayer data - a greyscale image that only needs one value for each pixel to represent red, green, and blue.

A really good brief and basic explanation of how sensors deal and interpret RAW data is here...
http://www.adobe.com/digitalimag/pdf...rawcapture.pdf

REDCODE compression is approximately 12:1 - which turns 323 into about 26MB/s.

Lucas
-----
ASSIMILATE, Inc.
LA, CA, USA.

[donatello b]

" impossible to me, since we have a datarate of ~30MB/s.
This is only slightly more than the compression of a DV Tape"

DV is 25Mbs ( that is b not B)which is about 3.5MBs ...

[Graeme Nattress]

Easy - DV is 25Mbits, whereas REDCODE RAW is somewhere between 24MBytes and 27MBytes, well over 8 times as much data.

Next, REDCODE RAW is neither 4:4:4 or any other number designation of chroma subsampling. It's RAW, and that means it just records a copy of whatever information hits the sensor. No data points are directly thrown away, just compressed with a modern wavelet based codec set at 12 bits.

Hope that helps,

Graeme

[IAN SUN]

To my understanding it is not really 4:4:4 as we are originating from a bayer sensor. There are two green pixels for every blue or red. So perhaps it is closer to 4:2:2, (but with some interpolation ?). There is no difference between RAW RAW and REDcode RAW in this respect, REDcode does not reduce the color information.

The Keys are indeed magnificent, I doubt you will need uncompressed unless you are a dedicated FX house.

[Graeme Nattress]

It's even more complex than that, Bro, as you're interpolating with the goal of full RGB in such a way that it looks good. Bayer algorithms are clever and give great looking resolution in both green and red and blue, so really, it's not a worry.

Graeme

[IAN SUN]

Thanks Graeme, if I had seen your previous post I wouldn't have even bothered responding!

[Andrew M.]

Ian, the best explanation that works for me about RAW is that RAW for Bayer sensors is one channel stream of data.

RGB will have 3 channels and 3XCCD RAW will have 3 channels.

The way you get RGB out of one channel is by exploiting the fact that Bayer pattern is always RGB (hast minimum one red two green and one blue pixels ) pattern each time you offset your reading by only one pixel on the sensor no matter what direction your offset will go.