New Red cameras – resolution glut?
The new cameras from RED were announced last week. There has been a lot of anticipation, especially towards the cheaper camera, named Scarlet. The announcement does bring up some questions, though.
http://www.red.com/epic_scarlet/
New cameras
I guess most people were happy with the announcement: 8 different cameras (”brains” and a whole slew
of attachments, accessories and modules. The “brains” come in two different flavors, Scarlet is the smaller, “lowend” (called professional) unit, Epic is the “master professional”, high end unit. Both come with several models, with different lens mounts and sensor sizes.
If you have not acquainted yourself with RED-technology, look at the presentation I made earlier this month: http://www.thingamagic.net/jussi/?p=7 Here is a recap: the RED One is a digital cinema camera, that captures images in up to 4K resolution (4096×2580) using a proprietary “raw” format, called Redcode or r3d. The camera is very cheap compared to other professional digital motion picture cameras, with the price starting at 17500 USD.
At the same time I found this interesting article, Redfacts. It is especially interesting considering that it is the first piece to really heavily criticize the RED camera that I have read. Not being too familiar with any of the systems discussed in the paper (Red One or Sony F23), I will not go into details of the paper too heavily. It did however raise some valid points, which I would like to ponder about.
Redcode
Redcode is a proprietary compression technology. It is heavily compressed, with bitstreams of either 25MB/s or 36 MB/s. Redcode can contain a 2K stream at 113fps or 4K at 30fps. As a comparison a datastream of 4K in an uncompressed form (like the DPX-files we use for post production) would be around 885 MB/s, and this with 10bit color, not the 12bit Red captures. This means only 1/25th of the data is left in the Redcode file. In the still-camera world, a raw-file means that all the information from the sensor is put in the file. Red has somehow turned that around, and here “raw” means that they have discarded most of the data available.
Processing Redcode needs a very powerful computer. Some NLEs support the files directly, but most systems require the file to be conformed into a format that tools in the post-production workflow can actually use. Sony makes most of this processing in the camera (which is definitely one of the reasons there is such a huge difference in the cost of the camera). Putting the processing outside of the camera itself seems like a prudent choice, with all the cost benefits and versatility connected to normal desktop computers.
Resolution
4K is the current highend standard for Digital Cinema, with 2K (2048×1300) being the norm for post production work and display. Most DCI projectors that theaters are equipping themselves with are 2K, the HD screens customers are buying for their homes are nearly 2K (2K=2048×1080, HD=1920×1080). In fact, the biggest digital films to date (Star Wars episodes II & III) were filmed with HD resolution cameras.
Red One was the first camera with the capability to shoot 4K inside any reasonable budget. 4K has been more prone to come into the postproduction workflow originating from normal 35mm film via a scanner. Now we will see more and more projects done in 4K, because Red makes acquisition possible and relatively affordable. This is reasonable, since 4K can be handled by most of the vfx and grading solutions used in a modern workflow, and it can be printed to film using up-to-date film printers. My colleagues also say that there is a visible difference material printed with 4K to 2K when projected from 35mm film.
The new Red cameras vary in resolution from 3K to 28K. Yes, 28K. Everybody can probably guess that the 28K camera is meant for very specialist uses. It creates a image with 261 Megapixels (28000*9334).
I just can’t figure out why the normal Epic cameras that are designed for motionpicture work also have a resolution between 5K (5120×2700) and 9K(9334×7000). Yes, we can print 8K to film using our Celco Fury, but will any one see the difference between 4K and 8K? There will be few uses for 9K in it’s native resolution, which means that the images from these cameras will be downsampled into 4K or 2K resolutions for display. Sure, the end result will be an extra crispy image with hardly any noise, but I’m still left wondering…
Red also came out with a new, higher datastream versions of Redcode, Red42 (Scarlet) and Red225 (Epic). This means that we are cramming a huge amount of data from the sensor into a comparatively tiny space. This means there will be more compression on the images than there was before. Earlier I came up with 1:25 with Red36 and 4K, now we will see compression ratios more to the tune of 1:78 (6K Scarlet) or 1:35 (9K Epic).
8K resolution is not a real option for a postproduction workflow either. A single 10bit 8K picture in DPX is about 249MB, which means a data stream of almost 6 GB/s. We are not likely to see realtime 8K performance from any workstation and hard drive combination in the near future. This means that the data will be downscaled to 4K in order for it to make it thru the workflow.
Wouldn’t everyone be better off using the same compression techniques with smaller resolutions? Capturing 4K @ 225MB/s would only result in a compression ratio of about 1:4, which is a huge difference. Less compression is always better, no matter how good the compression is. Does it really make more sense to oversample the image by a magnitude of 4 and then discard 97% of that data?
I appreciate any comments and ideas.