Tag Archives: ProRes

ProRes Raw Over Exposure Magic Tricks – It’s all smoke and mirrors!

There are a lot of videos circulating on the web right now showing what appears to be some kind of magic trick where someone has shot over exposed, recorded the over exposed images using ProRes Raw and then as if by magic made some adjustments to the footage and it goes from being almost nothing but a white out of over exposure to a perfectly exposed image.

This isn’t magic, this isn’t raw suddenly giving you more over exposure range than you have with log, this is nothing more than a quirk of the way FCP-X handles ProRes Raw material.

Before going any further – this isn’t a put-down of raw or ProRes raw. It’s really great to be able to take raw sensor data and record that with only minimal processing. There are a lot of benefits to shooting with raw (see my earlier post showing all the extra data that 12 bit raw can give). But a magic ability to let you over expose by seemingly crazy amounts isn’t something raw does any better than log.

Currently to work with ProRes Raw you have to go through FCP-X. FCP-X applies a default sequence of transforms to the Raw footage to get it from raw data to a viewable image. These all expect the footage to be exposed exactly as per the camera manufacturers recommendations, with no leeway. Inside FCP-X it’s either exposed exactly right, or it isn’t.

The default decode settings include a heavy highlight roll-off. Apple call it “Tone Mapping”. Fancy words used to make it sound special but it’s really no different to a LUT or the transforms and processes that take place in other raw decoders. Like a LUT it maps very specific values in the raw data  to very specific output brightness values. So if you shoot just a bit bright – as you would often do with log to improve the signal to noise ratio – The ProRes raw appears to be heavily over exposed. This is because anything bright ends up crushed into nothing but flat white by the default highlight roll off that is applied by default.

In reality the material is probably only marginally over exposed, maybe just one to 2 stops which is something we have become used to doing with log. When you view brightly exposed log, the log itself doesn’t look over exposed, but if you apply a narrow high contrast 709 LUT to it, it then the footage looks over exposed until you grade it or add an exposure compensated LUT.  This is what is happening by default inside FCP-X, a transform is being applied that makes brightly exposed footage look very bright and possibly over exposed – because thats the way it was shot!

This is why in FCP-X  it is typical to change the color library to WCG (Wide Color Gamut) as this changes the way FCP-X processes the raw, changing the Tone Mapping and most importantly getting rid of the highlight roll off. With no roll-off, highlights and any even slight over exposure will still blow out as you can’t show 14 stops on a conventional 6 stop TV or monitor. Anything beyond the first 6 stops will be lost, the image will look over exposed until you grade or adjust the material to control the brighter parts of the image and bring them back into a viewable range. When you are in WCG mode in FCP-X the there is no longer a highlight roll off crushing the highlights and now because they are not crushed they can be recovered, but there isn’t any more highlight range than you would have if you shot with log on the same camera!

None of this is some kind of Raw over exposure magic trick as is often portrayed. It’s simply not really understanding how the workflow works and appreciating that if you shoot bright – well it’s going to look bright – until you normalise it in post. We do this all the time with log via LUT’s and grading too! It can be a little more straight forward to recover highlights from Linear Raw footage as comes form an FS5 or FS7 compared to log. That’s because of the way log maintains a constant data level in each highlight stop and often normal grading and colour correction tools don’t deal with this correctly. The highlight range is there, but it can be tricky to normalise the log without log grading tools such as the log controls in DaVinci Resolve.

Another problem is the common use of LUT’s on log footage. The vast majority of LUT’s add a highlight roll off, if you try to grade the highlights after adding a LUT with a highlight roll off it’s going to be next to impossible to recover the highlights. You must do the highlight recovery before the LUT is added or use a LUT that has compensation for any over exposure. All of these things can give the impression that log has less highlight range than the raw from the same camera. This is not normally the case, both will be the same as it’s the sensor that limits the range.

The difference in the highlight behaviour is in the workflows and very often both log and raw workflows are miss-understood. This can lead to owners and users of these cameras thinking that one process has more than the other, when in reality there is no difference, it’s appears to be different because the workflow works in a different way.

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Why I Choose To Shoot ProRes Raw with the FS5

This is a much discussed topic right now, so as I promised in my last article about this, I have put together a video. Unfortunately YouTube’s compression masks many of the differences between the UHD XAVC and the ProRes Raw, but you can still see them, especially on the waveform scopes.

To really appreciate the difference you should watch the video on a large screen at at high quality, preferably 4K.

ProRes Raw and Atomos Inferno and Sumo – BIG deal for the FS5 and FS7!!

proresraw-logo ProRes Raw and Atomos Inferno and Sumo - BIG deal for the FS5 and FS7!!Over the last few days there have been various rumours and posts coming from Apple about how they intend to get back to providing decent support for professional users of their computers. Apple have openly admitted that the Trash Can Mac Pro has thermal problems and as a result has become a dead end design, which is why there haven’t been any big updates to the flagship workstation from Apple. Apple have hinted that new workstations are on the way, although it would seem that we won’t see these until next year perhaps.
Another announcement came out today, a new version of FCP-X is to be released which includes support for a new ProRes codec called ProRes Raw. This is BIG!

PRORES RAW.

Raw recordings can be made from certain cameras that have bayer sensors such as the Sony FS5 and FS7. Recording the raw data from the sensor maximises your post production flexibility and normally offers the best possible image quality from the camera. Currently if you record 4K raw with these cameras using an Atomos Shogun or similar the bit rate will be close to 3Gb/s at 24p. These are huge files and the cDNG format used to record them is difficult and clunky to work with.  As a result most users take the raw output from the camera and transform it to S-Log2 or S-Log3 and record it as 10 bit ProRes on the external recorder. This is a bit of a shame as going from 12 bit linear raw to 10 bit S-log means you are not getting the full benefit of the raw output.

Enter ProRes Raw:  ProRes Raw will allow users to record the cameras raw output at a much reduced bit rate with no significant of quality. There are two versions, ProRes Raw and ProRes Raw HQ. The HQ bit rate is around 1Gb/s at 24fps. This is not significantly bigger than the ProRes HQ (880Mb/s) that most users are using now to record the raw, yet the full benefit of 12 bit linear will be retained. A 1TB SSD will hold around an hour of ProRes Raw, compare that to uncompressed raw where you only get around 20 mins and you can see that this is a big step forwards for users of the FS5 in particular.

ProRes Raw (the non HQ version) is even smaller! The files are smaller than typical ProRes HQ files. This is possible because recording raw is inherently more efficient than recording component video.

It is claimed by Apple that ProRes Raw will play back in real time on MacBook Pro’s and iMacs without any additional rendering or external graphics cards, so it obviously isn’t terribly processor intensive. This is excellent news! Within FCP-X the playback resolution can be decreased to bring improved playback performance in less powerful systems or mutistream playback.

It looks like you will be able to record from a 4K DCI  from an FS5 or FS7 at up to 60fps continuously. This breaks through the previous limits for the Shogun of 30fps. The FS7 will be able to record 2K raw at up to 240fps and the FS5 will be able to record 4K raw at 100 and 120fps for 4 seconds. Other raw cameras are also supported by the Atomos recorders at differing frame sizes and frame rates.

At the moment the only recorders listed as supporting ProRes Raw are the Atomos Shogun Inferno and the Sumo19 and it looks like it will be a free update. In addition the DJI Inspire 2 drone and Zenmuse X7 Super 35mm camera will also support ProRes Raw.

Whether you will be able to use ProRes Raw in other applications such as Resolve or Premiere is unclear at this time. I hope that you can (or at least will be able to in the near future).

SEE: Apple Press Release.

SEE: Apple ProRes Raw White Paper

SEE: ATOMOS ProRes Raw INFO PAGE.

 

 

What’s the difference between raw and S-Log ProRes – Re: FS5 raw output.

This is a question that comes up a lot.

Raw is the unprocessed (or minimally processed) data direct from the sensor. It is just the brightness value for each of the pixels, it is not a color image, but we know which color filter is above each pixel, so we are able to work out the color later. In the computer you take that raw data and convert it into a conventional color video signal defining the gamma curve and colorspace in the computer.  This gives you the freedom to choose the gamma and colorspace after the shoot and retains as much of the original sensor information as possible.Of course the captured dynamic and color range is determined by the capabilities of the sensor and we can’t magically get more than the sensor can “see”. The quality of the final image is also dependant on the quality of the debayer process in the computer, but as you have the raw data you can always go back and re-encode the footage with a better quality encoder at a later date. Raw can be compressed or uncompressed. Sony’s 12 bit FS-raw when recorded on an Odyssey or Atomos recorder is normally uncompressed so there are no additional artefacts from compression, but the files are large. The 16 bit raw from a Sony F5 or F55 when recorded on an R5 or R7 is made about 3x smaller through a proprietary algorithm.

ProRes is a conventional compressed color video format. So a ProRes file will already have a pre-determined gamma curve and color space, this is set in the camera through a picture profile, scene file or other similar settings at the time of shooting. The quality of the ProRes file is dependant on the quality of the encoder in the camera or recorder at the time of recording, so there is no way to go back and improve on this or change the gamma/colorspace later. In addition ProRes, like most commonly used codecs is a lossy compressed format, so some (minimal) picture information may be lost in the encoding process and artefacts (again minimal) are added to the image. These cannot easily be removed later, however they should not normally present any serious problems.

It’s important to understand that there are many different types of raw and many different types of ProRes and not all are equal. The FS-raw from the FS5/FS7 is 12 bit linear and 12 bit’s are not really enough for the best possible quality from a 14 stop camera (there are not enough code values so floating point math and/or data rounding has to take place and this effects the shadows and low key areas of the image). You really need 16 bit data for 14 stops of dynamic range with linear raw, so if you are really serious about raw you may want to consider a Sony F5 or F55. ProRes is a pretty decent codec, especially if you use ProResHQ and 10 bit log approaches the quality of 12 bit linear raw but without the huge file sizes.  Incidentally there is very little to be gained by going to ProRes 444 when recording the 12 bit raw from an FS5/FS7, you’ll just have bigger files and less record time.

Taking the 12 bit raw from an FS5 and converting it to ProRes in an external recorder has potential problems of it’s own. The quality of the final file will be dependant on the quality of the debayer and encoding process in the recorder, so there may be differences in the end result from different recorders. In addition you have to add a gamma curve at this point so you must be careful to choose the correct gamma curve to minimise concatenation where you add the imperfections of 12 bit linear to the imperfections of the 10 bit encoded file (S-Log2 appears to be the best fit to Sony’s 12 bit linear raw).

Despite the limitations of 12 bit linear, it is normally a noticeable improvement over the FS5’s 8 bit internal UHD recordings, but less of a step up from the 10 bit XAVC that an FS7 can record internally. What it won’t do is allow you to capture anything extra. It won’t improve the dynamic range, won’t give you more color and won’t enhance the low light performance (if anything there will be a slight increase in shadow noise and it may be slightly inferior in under exposed shots). You will have the same dynamic and color range, but recorded with more “bits” (code values to be precise). Linear raw excels at capturing highlight information and what you will find is that compared to log there will be more textures in highlights and brighter parts of your captured scenes. This will become more and more important as HDR screens are better able to show highlights correctly. Current standard dynamic range displays don’t show highlights well, so often the extra highlight data in raw is of little benefit over log. But that’s going to change in the next few years so linear recording with it’s extra highlight information will become more and more important.

Convergent Design Gemini throws up a ProRes Issue. NOT THE PROBLEM I THOUGHT IT IS

OK, I wrote about this without digging deep enough. If you read the original article I claimed that ProRes was clipping my files at 104%. Well it’s NOT. The ProRes files are just fine, BUT some Quick Time applications are clipping the files at playback. In FCP the files are OK. Premiere appears to be reducing the level of the files a little and Quick Time player is clipping the files at approx 104. So this isn’t as big an issue as I thought, but you do need to keep an eye out as to what is happening with highlights and super whites depending on what software you are using. I was wondering why I hadn’t seen this before. In part it because I am no longer using FCP.