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X7 ProRes RAW overview and impressions
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TimDerLauch
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Thanks for sharing !
2018-8-8
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Barry Goyette
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I had a shoot cancel this morning so I had a few minutes to set up the I2 with some charts and cycle through the speed settings of both EI mode and Normal mode in Pro Res Raw. As we suspected from last nights conversation, Normal mode is clipping the highlights at higher EI settings rather severely...in a way that seems strange to me compared to other cameras I own, but perhaps it's not by mistake. This encoding, while essentially throwing away a huge amount of latitude, is a near perfect match for how DJI encodes Normal ProRes d-cinelike, and most surprisingly, how it encodes Normal mode Cinema DNG. I generally steer clear of both normal mode, and higher speed ratings, so this phenomenon is something I've never seen. Props to Salvador for the comments that led us to this point.



One thing I'm curious about is what happens in PRR when you shoot at higher EI, but then adjust exposure downward to avoid clipping the highlights. Obviously we'd be able to get the highlights back at some point...but I'm curious what that does to the shadows.  I guess another test is in order  :-).

As part of these tests today, I did confirm that EI mode Pro Res Raw behaves much like EI mode has always behaved...meaning that there is no quality difference between shooting with the camera rated at 100 or 1600 (or really anywhere in between). When matched in post, both have identical shadow noise, color and tone separation, and the highlights have identical latitude and detail. What matters most with EI mode is actual exposure settings (light level, shutter, aperture), EI mode simply redistributes the entire range captured depending on the chosen rating.

The question then becomes, if all speed ratings (EI) are capturing the same information, which one do I choose? Personally I choose the lower "base" ISO for a couple of reasons. LOG gamma's like EI mode tend to not like being underexposed...as doing so tends to expose it's main weakness as a gamma -- noisy shadows. Shooting at 100 in a way is like "shooting to the right"...it tends to enforce sending more light to the sensor. Shooting at higher speeds can, even when monitoring the waveform, influence exposure in the opposite direction...shooting to the left if you will. For someone interested in recovering additional highlight detail from their shots, this may be a good strategy, but it comes generally at the expense of overall dynamic range (due to underexposure), and increased noise in the midtones and shadows.

I'm curious to hear from Salvador, and others who might normally choose to shoot at higher speed ratings in EI mode, given the agnostic relationship it has with speed ratings, what benefit do you realize from those higher EI settings?


2018-8-8
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Salvador Garza
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Very interesting indeed!  I've only had the I2/X7 for a couple of weeks, and have had only a handful of opportunities to shoot with it. On my first shoot I decided to shoot ProRes RAW with EI Mode turned off in order to set the SD Look to Cine Like (which is what I've been shooting for a while now with a P4P). When I compared the H264's from my first shoot with the ProRes RAW footage I was disappointed to learn both clipped at around the same point. After having watched several demos/tutorials on ProRes RAW (mostly from Atomos) I knew something wasn't right. The RAW file should have more info than a "Rec709-ish" non-log recording (D-Cinelike). A bit of context,  I've been shooting mostly industrial plants during twilight with the I2/X7 so that twisted my arm into shooting in the higher ISO / EIs. Most of these plants don't look very attractive during daylight, so haven't had much opportunity to play around with lower ISO / EIs.  Also, DJI's D-Log white paper seems to imply the D-Log curve was created for EI 1600 and the rest of the curves derived from there, for some reason that re-assured me that shooting @ EI 1600 or slightly below would be ok.  For my second shoot I decided to switch EI Mode on, and now all of a sudden I had access to all the information captured by the sensor.   Even though I set the EI to 1600 for most shots, I did overexpose by a stop (effective rating it at EI 800 which helped with the noise).

In terms of workflow, I'll make my selects marking in/outs and favoriting those ranges. I'll set the RAW to Log conversion on all the clips to D-Log. I'll then drop all my favorites into a project/timeline with the same  frame dimensions/frame rate. I'll use Primaries Exporter (App Store) to export the timeline as individual clips (ProRes 422HQ or 4444). Then off to Resolve, add three nodes to each clip: the middle node will have DJI's X7DLog2Rec709 3D LUT. I'll use the first and last nodes to grade before/after LUT (soft clipping, noise reduction, etc etc).  Hoping Resolve will support ProRes RAW soon, or at least Apple's Compressor. Would be nice to batch convert PRR with RAW to Log conversion using Compressor.
2018-8-9
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Barry Goyette
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Its interesting, because of my little foray into the land of EI 1600 yesterday, now go4 seems to want to default to that for me, leading several of my shots last night and this morning, to be rated at that setting, and a general freak-out when I looked at the footage today. (entire frame blown out). Nothing to worry about, once all the conversions are set and corrections applied, the footage looks largely the same as the ISO shots of the same subject...but ...well....one thing I notice is that while indeed the info is identical in the file theres sort of an opposite set of problems during grading. Typically I find my ISO 100 shots grade well, but that the shadows can seem compressed and it takes some work to open them up using FCPX's tools. Well the ISO 1600 files had similar difficulties with the highlights...at least given the shots I had to work with. All the detail is there, but digging it out of these compressed looking highlights was just harder. There may be some wisdom rating EI mode at 400 as simply it's placing 18% grey somewhere in the middle. I remember during ProRes EI mode testing that I determined EI 200 seemed to give a more easily gradable file (although for some reason, I still shoot 100). Oh...and, one of the things I noticed on those 1600 clips, is that, as I suspected, at least for what I was doing, the Waveform in go4 was really difficult to gauge.

Interesting also your use of EI mode at 1600. Using Log gammas at higher ISO's to increase sensitivity (push the image) has always been something that you hear people like Alistair Chapman say not to do. Especially in Raw, EI mode gives you identical results at every rating, given the same exposure. So if you're using 1600 in order to get the f-stop you need, then shooting at that fstop, at EI 100, would give you the same result, but also let you know that you're underexposing like hell.  Certainly, it's nice to actually see the image on the monitor :-) so there's a reason to shoot at higher speeds, but maybe an intermediate rating would result in images that have better exposure due to the "psychology of the monitor image".  FWIW I shoot at end of day all the time with 100, although I don't  shoot later than 30 mins past sunset, so I don't know about that situation. Every once in great while I'll crank it up to 400.

As for DJI's curve and the 1600 rating. I'd give that a bit of a grain of salt. Their language there is a little squishy.  Essentially they should be saying that 1600 is the maximum EI that gives full dynamic range, and that EI mode is structured so that saturation with 1600 is equal to the maximum code value. As those curves show all of the EI following the same shape and capturing the same DR,  it's more about how those curves relate to the waveform than anything.
2018-8-9
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rmaxwell.dccnet
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Barry Goyette Posted at 2018-8-8 11:38
I had a shoot cancel this morning so I had a few minutes to set up the I2 with some charts and cycle through the speed settings of both EI mode and Normal mode in Pro Res Raw. As we suspected from last nights conversation, Normal mode is clipping the highlights at higher EI settings rather severely...in a way that seems strange to me compared to other cameras I own, but perhaps it's not by mistake. This encoding, while essentially throwing away a huge amount of latitude, is a near perfect match for how DJI encodes Normal ProRes d-cinelike, and most surprisingly, how it encodes Normal mode Cinema DNG. I generally steer clear of both normal mode, and higher speed ratings, so this phenomenon is something I've never seen. Props to Salvador for the comments that led us to this point.


Hi Folks,

First let me say that this thread has been one of the richest collections of information about ProRes RAW I have seen.  Thank You Barry and Salvador for your contributions.

I stumbled across a webinar at the Visual Impact site that I think you would enjoy.  While it is 90 minutes long it gives many hints in shooting ProRes RAW.  It is specific to Sony and Atomos but you can get many details about what ProRes RAW is and how to process it in Post.  You can skip the Sony setup and exposure if you wish and only watch the Post part.  I have given the time codes for each section.
http://www.visuals.co.uk/visualsblog/prores-raw-alister-chapman/

I found it very informative.

Be sure to click enable cookies.  Also the video only contains audio and slides.  There are no talking heads.

0
   House keeping
00:04:12
   What is ProRes RAW
00:22:29
   Sony and Atomos setup
00:45:29
   Exposure
01:09:30
   Post Production in FCP X

Note that with the DJI X7 you would use the following settings in FCP X:

RAW to Log Conversion           DJI D-Log
Camera LUT                               D-Log to Rec 709

Enjoy

Ray

2018-8-10
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Salvador Garza
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rmaxwell.dccnet Posted at 2018-8-10 12:27
Hi Folks,

First let me say that this thread has been one of the richest collections of information about ProRes RAW I have seen.  Thank You Barry and Salvador for your contributions.

Thanks Ray! This is one of the best resources out there on ProRes RAW
2018-8-11
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MFPF
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Very nice pictures. Thanks.
2018-8-11
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Salvador Garza
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Here's DJI Support's sad response to this issue:

"We coordinated your issue to our Engineers. We would like to informed the reason why ProRes RAW behaves differently when EI Mode ON or OFF ua because when EI Mode is ON, the color mode changes to D-log, which can extend the latitude. The native ISO is 500 when EI mode is ON and D-log color mode is chosen."

Make some wonder if there's an Apple ProRes RAW certification process or it's only licensing agreement

2018-8-15
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sandeeptinku
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SnapTube hd is a popular Android app that can download online videos in a matter of seconds.
2018-8-16
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Barry Goyette
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Salvador Garza Posted at 2018-8-15 15:37
Here's DJI Support's sad response to this issue:

"We coordinated your issue to our Engineers. We would like to informed the reason why ProRes RAW behaves differently when EI Mode ON or OFF ua because when EI Mode is ON, the color mode changes to D-log, which can extend the latitude. The native ISO is 500 when EI mode is ON and D-log color mode is chosen."

That’s a bit of a classic response from support, isnt it? General lack of understanding of the question, followed by incorrect info. :-) As I mentioned before, their stated native iso info shifts with the wind— 500 is for the old d-log, you can’t even set EI mode to 500.. but it still gets quoted. And Raw is encoded as linear, not D-log, (thus the conversion step in FCP), yet support throws that out as fact to explain the "why"... as if it came from engineering. It didn’t.. I’ve spoken with dji engineers on this forum, and they have a firm grasp on how these gamma’s are encoded. Maybe we can roust one of them. FWIW.. I’ve sent a request through US support for them to check encoding on both EI mode and normal mode.. I wouldn’t imagine any change till late fall..
2018-8-17
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fans292ec034
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EXCELLENT VIDEO
2018-8-21
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Camonyx
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Hi Salvador - interesting video - could you let us know what the conclusion is whats the optimal settings for A. a lowlight scene B daylight scene - tx
2018-9-8
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Flo the Pirate
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i wish other forum posts would just have 10% of the knowledge presented here - guys I love it ! thank you !
2018-9-21
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rtrhbbbbbtg5tgg
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Thank you for sharing Barry such an important post.  Keep it up continue.........


2018-11-27
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imdavidshannon
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I am gonna start crying if you post such amazing footage I also need a drone

2018-12-13
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fansa5f7085a
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Barry Goyette Posted at 2018-8-8 11:38
I had a shoot cancel this morning so I had a few minutes to set up the I2 with some charts and cycle through the speed settings of both EI mode and Normal mode in Pro Res Raw. As we suspected from last nights conversation, Normal mode is clipping the highlights at higher EI settings rather severely...in a way that seems strange to me compared to other cameras I own, but perhaps it's not by mistake. This encoding, while essentially throwing away a huge amount of latitude, is a near perfect match for how DJI encodes Normal ProRes d-cinelike, and most surprisingly, how it encodes Normal mode Cinema DNG. I generally steer clear of both normal mode, and higher speed ratings, so this phenomenon is something I've never seen. Props to Salvador for the comments that led us to this point.

https://vimeo.com/284002048

Hi Barry and Salvador,

I have a little problem with the post-prodction of my Prores Raw footage...
On Final Cut Pro X I'm not able to put it on D-Log, as you can see on my picture I don't have all the option you guys have on the Inspector Info... Do you know why?
Also do you know how do put them on Davinci Resolve for grading? Do we need to export it in Apple Prores 4444 and do the grade with this file?
Thanks you!

Fred,

2019-1-8
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fansa5f7085a
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imgur.com/a/C6VzOmF
2019-1-8
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mobilelegends
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Very nice article and msg we likes so much
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2019-3-20
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