Shooting in Raw

[Dan Keaton]

Dear Friends,

We are looking for some opinions on why users choose to shoot Raw or not.

We produce a video recorder, the Gemini 4:4:4 that can record ARRIRAW from an ALEXA camera, but we are interested in RAW in general.

But specifically for the ARRI ALEXA, we find that many shoot internally in ProRes when shooting with the ALEXA, especially for eposidic television.

Of course, this makes sense to us.

But for others that want higher image quality, one can use an ALEXA with an ARRIRAW recorder to shoot in ARRIRAW.

It is reasonable to assume that one, in the past, may have choosen not to shoot ARRIRAW, due to the cost of owning or renting an ARRIRAW recorder.

Now, the cost of an ARRIRAW recorder with media, has been greatly reduced.

So, we are looking for reasons why a production would, or would not choose to shoot in RAW. And while I have mentioned ARRI ALEXA in this post, I am looking for opinons about RAW in general as there are many RAW cameras available today.

We would like to know if there are barriers, real or imagined, to shooting Raw.

Respectfully,


Dan Keaton
Convergent Design (Designers of the nanoFlash and Gemini Recorders)

[Sareesh Sudhakaran]

I'd like to venture a few guesses by playing the devil's advocate:

1. The average professional photographer deals with situations where lighting conditions are terrible, if not impossible. To make matters worse, he/she has to deliver great looking photographs in print, either for fine art (300 to 720 ppi) or for magazines at 300 dpi. Even a wedding photographer has to consistently deliver great prints. 14 or 16-bit RAW is a life saver.

On the other hand, the professional videographer usually has lights at his/her disposal, and even if he/she were shooting wildlife for broadcast, the delivery specs are not that demanding. DCI for cinema is happy with JPEG compressed images. BBC is okay with interframe or intraframe codecs at 50/100 Mbps in 8 bit, and the color space/dynamic range/resolution of standard display devices/projection systems are worse than what is possible with print. Average television screens push 100-150 ppi.

Only the most demanding productions require RAW, in theory. Let me repeat, in theory. Really good green screen work is possible with 4:2:2 and 4:4:4 sampled 8-bit video. And any advantage RAW has evaporates due to the poor display technology currently available.

If I'm shooting green screen, am I better off with RAW or with an uncompressed TIFF/DPX image sequence in 32-bit float in Wide gamut RGB? Is the dynamic range of ARRIRAW considerably higher than Prores on the Alexa? I don't know. How does footage being in RAW practically translate to an advantage in the traditional video workflow?

2. Software. All still camera manufacturers release dedicated RAW software with specialized algorithms to take advantage of the unique mathematical properties of RAW files.

Is the current line up of ARRIRAW software really on par with still RAW algorithms? Even if the answer is yes, does the market know this? On the other hand, consider BM's Cinema camera and their choice of DNG - now that's a smart choice. Third party developers have an open protocol that encourages development, and has Adobe as backup. The last thing the world needs is another RAW wrapper.

3. Archival. Tape based formats are almost dead. How many more years will HDCAM SR be around? If only a few recorders can 'read' ARRIRAW, what can I expect 20 years down the line?

If I'm forced to choose a color space and image sequence format (or any other compression codec) for post and archival, why not shoot in a format that takes me there more directly? Aren't there too many steps in a video workflow anyway? Is the problem with ARRIRAW that it is too good?

What if a recorder can take ARRIRAW and out-prores or out-dnxhd the internal Alexa software engine? Or better yet, what if it can convert ARRIRAW to a DNG image sequence?

4. Price. Simple question: A production that can afford Arriraw and the hardware required to process it in post is not going to complain about the cost of the recorder, is it? Does the recorder convert ARRIRAW into a cheaper format for post (see point 3 above) that is better than the prores or dnxhd that comes out of the alexa internally?

Just out of the top of my head.

To make things clear: If I had the money, the only camera I would want to shoot with would be the Alexa. And I would shoot in Arriraw.

[Chris Medico]

I have to balance cost and complexity with the budget when working on projects. To put it simply RAW costs more and doesn't always have a benefit equal to that cost for the project.

For me to shoot RAW on my average project I would have to have either enough storage to shoot till I could offload or have at least one extra person to data wrangle during a shoot. Increases cost.

When I get back to the shop I have to transfer the footage to the editing system. RAW takes much longer to transfer so I may not be able to get to work right away. I have to plan around what could take a few hours time to copy footage. Possible increase in cost.

Storage space and bandwidth demands. RAW takes up a lot more space and requires much higher bandwidth capabilities in the storage system. You aren't going to get multiple streams of RAW HD from a single drive. You are going to need RAID for your RAW. Increase in cost.

Project archiving. The other issue with the large RAW footprint. Long term storage. It isn't trivial to archive a large project SAFELY. Do we trust old hard drives or stacks of burnt optical disks? How often do we need to go through and refresh our digital archives?? The larger they are the longer this will take and the more it will cost in media. For sure an increase in cost.

My point is this - the project needs must dictate that RAW is the best option for what it is going to cost you in money and time. How many projects need this level of quality in the video? Those that do should absolutely use it. Those of us that don't need it are better served going with reasonable compression and using that capital towards equipment and expenses that help us generate better returns for our business.

[Dan Keaton]

Dear Sareesh,

Thank you for taking the time to post your opinions.

Here are some of my thoughts, then I will respond to your points.

In the case of the ARRI ALEXA, recording to ProRes internally in the camera is easy, and it has proven to be good enough for episodic television.

For shooting features or high-end commercials, we are told that production companies want a higher image quality.

When recording RAW, one gets the highest quality image out of the ALEXA and one also gets lots of metadata.

When one records internally in the ALEXA, the image is debayered in the camera, and certain settings are baked in. Shooting in ARRIRAW, the image is not debayered in the camera, or a recorder like the Gemini 4:4:4. This allows much more processing power (computing power and time) to be devoted to getting the absolute best image possible.

And, Post can pull out more details, in the shadow areas, or in the highlight areas, since the image is not baked in.

An unexpected result, is that if one records HD, 1920 x 1080 10-Bit in full uncompressed 4:4:4, the file size is actually larger than recording ARRIRAW, 2800 x 1620 (photosites) in 12-Bit Log.

Thus ARRIRAW is good for archiving. And, since debayering gets better over time, one may be able to re-debayer the images in the future and get even a better image.

Now, responding to your points.

2. The better the image, the better the key for greenscreen work.
We see this all of the time, even with our nanoFlash. Recording high-quality 4:2:2 makes for a better key.

And of course, we are speaking of much better image quality when we speak of RAW.

When shooting green screen, full uncompressed or RAW should both be great.

When recording in RAW, such as ARRIRAW, one then processes the ARRIRAW to create whatever level of quality one wants. This could be DPX (Full Uncompressed), or a high quality compressed codec, maybe ProRes 4:4:4 or Avid DNxHD 440, or even something else.

This level of flexibility is great, as one can use a lower quality now, and later obtain a higher quality, just by reprocessing the RAW file.

3. Archival. For ARRIRAW specifically, one can reasonably expect programs to convert ARRIRAW to another format for many years to come. Major Hollywood pictures have been recorded in ARRIRAW. And one just needs the data, it does not have to be in any specific medium, such as tape, disk, or other medium, one just needs to be able to read and process the data.

4. Our research, has indicated that the cost of the recorder and media, in the past, which typically cost as much as the camera, was a problem. Now the cost of the recorder and media is a small fraction of what it used to be, eliminating this concern.

Sareesh, I greatly appreciate your post. Thank you for helping us in our research.

[Dan Keaton]

Dear Chris,

I also want to thank you for your thoughts.

When the Gemini 4:4:4 and our new Thunderbolt capable Transfer Station, we can transfer footage from 325 to 375 Megabytes per second (MBps).

To put it differently, 60 minutes of footage takes approximately 30 minutes to upload to a Promise Technologies Pegasus Raid.

iMac with dual Thunderbolt = around 375 MBps
Mac Mini with single Thunderbolt = around 325 Mbps

We agree completely, the project should dictate the need for RAW or not.

[Chris Medico]

Originally Posted by Chris Medico

I have to balance cost and complexity with the budget when working on projects. To put it simply RAW costs more and doesn't always have a benefit equal to that cost for the project.

Just to clarify this is in relation to the Sony 4k RAW which will have similar storage requirements as 1080 uncompressed.

[Alister Chapman]

One of the key benefits of a raw workflow is that normally you will be working at a higher bit depth, at least 12 bit if not 14 bit or 16 bit. This in turn allows the use of linear capture as opposed to the log capture normally associated with conventional video.

Don't get me wrong, log capture and recording (even things like hypergammas and cinegammas are closer to log than linear) is very good and works remarkably well. But it is limited as it compresses highlight information. Each extra stop of over exposure with a linear recording will contain twice as much data as the previous, while with log each stop contains the same amount of data, so as a result each brighter stop only has half as much information as the previous. Log does allow us great scope when it comes to grading and post production image manipulation, but the higher up the exposure range you go, the less data you have to work with, so how much you can manipulate the image decreases with brightness. As our own visual system is tuned for mid tones this log behaviour goes largely un-noticed. But as modern sensors achieve greater and greater dynamic ranges log starts to struggle while linear copes much better.
It's not until you try linear raw with a camera like the Alexa or F65 that you realise just how forgiving it is. In log mode the Alexa (and other log cameras like the F3) need to be exposed accurately. Over expose and you risk not only your highlights blowing out but also it becomes harder to get good looking skin tones as these may be up in the more compressed parts of the curve. However with linear, it doesn't really matter if faces are higher up the range, jus as long as they are not actually at sensor overload.
When you shoot with a log camera it must be treated like any other conventional video camera. Exposure must be correct, you need to watch and protect you highlights, expose to the left etc. A camera shooting raw behaves much more like a film camera, you can afford to push the exposure higher if you want less noise, just like film.

But linear raw comes at a cost, mainly a time and storage cost. We have become very used to the simplicity of working with video. Modern file based workflows are fast and efficient. Raw needs more work, more processing, more storage (compared to compressed at least). But computers are getting faster, storage is getting cheaper. Right now I believe that raw is only going to be used by those that really do need and want the very best flexibility in post production while log will become more and more common for episodic and documentary production. But, the time will come when we can handle raw quickly and easily and then perhaps we will look back at legacy codecs and wonder how we managed. Although saying that, while we still broadcast and distribute programmes using backwards compatible legacy gamma with it restricted dynamic range for display on devices with only 6 stops of display latitude, a general shift to raw with all it's extra overheads may never happen.

[Sareesh Sudhakaran]

Originally Posted by Alister Chapman

One of the key benefits of a raw workflow is that normally you will be working at a higher bit depth, at least 12 bit if not 14 bit or 16 bit. This in turn allows the use of linear capture as opposed to the log capture normally associated with conventional video.

Please correct me if I'm wrong but essentially 12-16 bit RAW is not the same as 12-16 bit RGB - the RAW converter still has to process the individual data for each pixel and create an RGB image, and assign it a color space, gamma, etc - there's a lot of potential for voodoo here.

At least as far as Blackmagic is concerned, I'm sure Resolve will handle the native cDNG files well - SpeedGrade does too, supposedly. It's everything else I'm worried about - effects, titles and other stuff have to be natively added to RAW, but how - if one is editing native?

[Alister Chapman]

Your quite right that raw is different to RGB, not sure why you think I'm saying otherwise?

With a native raw editing workflow the software will have to decode the raw image on the fly and convert it to RGB or YCbCr. Your titles etc will be in RGB or YCbCr. This will be extremely processor/GPU intensive and may require reduce resolution or other shortcuts to make it happen in real-time especially if your building up layers of clips or effects.

[David Heath]

Originally Posted by Dan Keaton

In the case of the ARRI ALEXA, recording to ProRes internally in the camera is easy, and it has proven to be good enough for episodic television.

For shooting features or high-end commercials, we are told that production companies want a higher image quality.

When recording RAW, one gets the highest quality image out of the ALEXA and one also gets lots of metadata.

I think it's highly important to make it clear that RAW won't necessarily give any higher image quality in the end - what it WILL do is allow for far greater versatility in the post process.

The question then becomes whether that versatility is worth the disadvantages? And here it's worth being clear what the downsides of RAW are - fundamentally that all the footage needs work done to get a viewable product, and that can add extra cost

So is RAW worth it? For such as news the answer must be no, for such as a feature film the answer is far more likely to be yes.

If it's possible to get the "look" right in camera, RAW offers little extra, and adds disadvantages. If you want to keep options open - and the "look" of a scene in a feature film may not be finalised until late in production - RAW offers a great deal.

What it does NOT offer is better image quality per se.

[Dan Keaton]

Dear David,

For practical, high end cameras that are available today, ones that can output raw and can record internally, the raw output can provide higher image quality.

Using the ARRI ALEXA as an example of such as camera, the internal ProRes recording is limited by the fact that the debayer of the image must occur in real time, and the processing power in the camera is limited by the amount of electrical power available.

The image can be debayered in real-time, but a better debayer, and thus a higher quality image, can be obtained when a faster, more powerful computer can be used, and additional processing time can be devoted to each frame of video.

[David Heath]

Point taken, certainly in principle. I can't pretend to have any figures but I wonder just how big any such quality improvement will be? My suspicion is nowhere near big enough to normally compensate for the more complicated workflow.....?

Whereas the gain from potential extra flexibility from RAW is an order of magnitude higher.

[Sareesh Sudhakaran]

Originally Posted by Dan Keaton

Using the ARRI ALEXA as an example of such as camera, the internal ProRes recording is limited by the fact that the debayer of the image must occur in real time, and the processing power in the camera is limited by the amount of electrical power available.

The image can be debayered in real-time, but a better debayer, and thus a higher quality image, can be obtained when a faster, more powerful computer can be used, and additional processing time can be devoted to each frame of video.

Dan, in your opinion, what is the Lightroom/CaptureOne Raw processing engine equivalent for the ArriRaw?

[Dan Keaton]

Dear David,

We have been working on images that show the actual difference.

As soon as possible, we will post them here.

[Jim Arthurs]

A couple weeks ago I decided to do a simple test of the Alexa recording in camera Prores vs ARRIRAW via the Gemini 4:4:4 with upgrade.

I had not seen ANY public tests anywhere and suspected the reason for this was that the difference was so slight that you'd need to do 2X magnification, image differencing, and all kinds of viewing enhancements in order to see something, anything.

After all, most TV series and even a few decent budgeted feature films have opted for Prores recording over ARRIRAW. So, to my mind, if they're NOT shooting ARRIRAW it was because the picture advantages aren't worth the significant extra expense for a recorder costing half or more the camera with a complicated workflow and the associated hassle of extra data and file management.

I was wrong in my assumptions! ARRIRAW reproduces fine detail that is completely blurred over by the in-camera de-bayering, processing and recording to Prores.

http://ftp.datausa.com/imageshoppe/o...RAWexample.png

http://ftp.datausa.com/imageshoppe/o...SvsARRIRAW.png

Simply put, if you record Prores you're "blind" to a good 25% of what the camera is capable of giving you in terms of detail. Is that important? Depends, of course! If you're making a web video or some project that has limited shelf life, then maybe not. But even here, if you're doing green screen you're compromising by not having what the camera is capable of giving you.

But, now, with an inexpensive recording option for ARRIRAW called the Gemini 4:4:4, one that is lightweight, doubles as a monitor and uses media that per minute is many factors cheaper than my first P2 cards with the prosumer HVX200 I owned generations back, then the case for NOT shooting ARRIRAW on any project that needs to have shelf life is greatly diminished. And, I have to wonder how many DP's are getting to see true side-by-side comps and how many producers are then making informed decisions?

And for the test I did, the workflow was simple and straightforward and no more complicated than shooting with any outboard recorder combo like an EX1 and a nanoFlash. An added bonus, as mentioned, was that the Gemini was the only on-camera monitor as well (no viewfinder on this particular Alexa). The SSD cards recorded by the Gemini played straight into Premiere CS6 from the eSata reader I was using, and I had good full frame rate playing the native ARRIRAW files. Obviously you need a RAID for serious work, but the ARRI "Shoot and Edit" mantra is still a valid one with ARRIRAW due to the acceptance of the file format in editing apps and the reduction in size, cost, media and power requirements for the actual recorder. Remember, ARRI "gives" you ARRIRAW for free... it's just not been all that practical to record it.

Alexas, for the most part, shoot TV series and movies. Almost without exception, this programming is an ASSET that will be mined for revenue for years (decades) to come. Recording ARRIRAW, while not true 4K, still goes a long way in future proofing these productions in a way that is simply impossible with on-board recording. Even now, ARRI has just released new de-bayering improvements that will glean additional quality from the same ARRIRAW footage shot when the cameras were first released. It's a pretty safe bet that when you re-approach your archival footage in a few years you'll get even BETTER results than today. This isn't a new concept, the RED folks and users understand this quite well, as footage shot with the first RED cameras years ago looks even better when processed anew with the latest de-bayer code.

Disclaimer, I know and like Convergent Design, and used their Alexa and a borrowed Gemini 444 for this test.

Regards,

Jim Arthurs