Hi,

I was testing RAW recording today with the Inspire 2 X5S after having noticed issues with flashing white and black pixels when recording with raw in low light (stationary, not flying) as described in this thread here: https://forum.dji.com/thread-91539-1-1.html

I wanted to see how the camera performs in normal, probably even too bright conditions (I dont have ND filters yet, so this was using faster shutter speed to not overexpose)

With These settings in Davinci, this is the Cinema DNG RAW file in Davinci:

Picture 1: https://ibb.co/ebhGgQ

Now after changing color space to Blackmagic Film and grading the footage with a LUT, look at the top right corner and notice the increase in noise in the blue sky:

Picture 2 Graded: https://ibb.co/kxaaak


I have also uploaded the actual Cinema DNG RAW file from the SSD for anyone who would like to check:
Dropbox: https://www.dropbox.com/s/tso4gg ... 407_R08634.dng?dl=0


Am I using the wrong settings in Davinci/Go App 4?

Any advice would be appreciated, many thanks

Try setting Color Space: REC709 and Gamma : LINEAR....then grade

Hi raven4, thanks for response.When I try that, this happens:

JBSonic Posted at 2017-4-7 11:37
Hi raven4, thanks for response.When I try that, this happens:
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That's irrelevant if you haven't graded. If you have the capability to look at some scopes(wfm or histogram), what you'll see is the greatly expanded dynamic range. It's so great, it exceeds the limits of REC709, but, with a good color grading app, you can dial things back into range, recovering all that out of bounds (in REC709) data, instead of clipping it. A nicely graded image(exposure, contrast and limits) looks pretty nice. Looks like you're using resolve....that's great for this grading.

Yes I know that there is significant dynamic range available, but when switching to linear when in the Rec709 color space, the image looks way too underexposed, far more then it should be.
Pulling it back  in post results in significant noise:

I am looking for the ideal workflow to have the cleanest possible picture when graded in Resolve. I have not used noise removal yet which I shouldn't have to considering this is shot in bright sunlight. You noticed the extreme amount of noise in the sky and this is Shadows +100% and highlights reduced.

That's because when you're working with LINEAR, the optimal ISO is 500. So, if you shot at ISO100, you're 2.3 stops underexposed.
Also, I recommend grading in the LOG mode. Use the OFFSET control to balance the scope, then use the CONTRAST control to set the appropriate range, 16-235 IRE.

I dont know why the meta data says that it was shot at iso100, because it was shot in RAW Dlog, which locks the ISO at 500 ?

JBSonic Posted at 2017-4-7 15:15
I dont know why the meta data says that it was shot at iso100, because it was shot in RAW Dlog, which locks the ISO at 500 ?

yeah, I discovered that too. Some programmer forgot to reset the header info.

So I have taken some more footage again today in RAW Cine DNG.

Recorded with REC709 - DLOG settings at 5.2K
Camera settings were: Iso (locked at  500 obviously)
Shutter 120
Aperture was high.
fps: 29.97

Still no ND filter so hence the high shutter.
Opened in Resolve with these settings: Just a 1.5 exposure reduction, otherwise Rec709, Linear




With some corrections like pulling up the shadows and reducing highlights, the image can be improved at the cost of significant noise!




Now when changing the raw settings to Blackmagic Film it produces less noise.




BUT it introduces White and Black Pixels flickering all over the footage, when you zoom in, you see the same pixels flickering on off in either black or white:


It is the same problem that I have described in this video a few days ago:



As it stands I achieve better results capturing in ProRes. What is the correct workflow for RAW Cine DNG in Davinci ?
Or are other settings responsible for the noise and pixel flickering?
Davinci works well with Sony RAW or Blackmagic camera RAW footage.

I've been after DJI to define the proper workflow, for weeks. So far, this is all they've said...
https://forum.dji.com/forum.php? ... mp;page=1#pid753269

raven4 Posted at 2017-4-8 09:23
I've been after DJI to define the proper workflow, for weeks. So far, this is all they've said...
https://forum.dji.com/forum.php?mod=viewthread&tid=90410&page=1#pid753269

I've been having good success with using a linear light to a  709 LUT. These are canned LUTS that come with Resolve. Under 3D, look into VFX IO, where you'll find some Linear-to-??? conversion LUTs.
Another suggestion: The order in which you apply LUTs and grading input is very important. Trying to grade an image with a node AFTER the application of a LUT is a pretty good way to clip information. I make it a practice to always input grading adjustments BEFORE the LUT is applied to be sure all the available info is pulled into range. Most (all) LUTs assume the input signal is legalized REC709.

Thanks for the advice raven, the Linear to Luts did provide some good results. But the main issue remains which is a lot of noise and white and black pixels flashing.
I think the problem might be caused by the incorrect meta data? If the meta data encoded  is set to iso100 rather than 500 used for DLOG RAW, then this would explain my vastly underexposed images.
But I am not sure, how is the noise on your Cinema DNG images in Resolve? And do you also see the white and black pixels flickering?

JBSonic Posted at 2017-4-9 09:40
Thanks for the advice raven, the Linear to Luts did provide some good results. But the main issue remains which is a lot of noise and white and black pixels flashing.
I think the problem might be caused by the incorrect meta data? If the meta data encoded  is set to iso100 rather than 500 used for DLOG RAW, then this would explain my vastly underexposed images.
But I am not sure, how is the noise on your Cinema DNG images in Resolve? And do you also see the white and black pixels flickering?

I don't think the problem is metadata related.
It's normal for data that is being displayed in a linear format to look underexposed. That happens because the gamma function is no longer artificially boosting the luminance, as it would do if you were using something like a gamma 2.4. There's a lot of info out there about grading in linear color space. Just be aware that the images will look too dark(underexposed).
The next point I'll make is that I've been examining my own DLOG images for missing pixels, as your experience has set me to wondering about it. I have to say that i am not seeing these hot spots, like you're seeing. It leaves me wondering of something is amiss with your sensor. I'm not seeing the noise you're referring to. Maybe, someone else will jump in here to offer their experience.-Bill

I'll offer two (maybe three :-) thoughts. I'm not getting a good picture about where your exposure is on these, but from what I can tell, it looks like you're underexposing a bit. You mention several times about lifting the shadows, and if you are really shooting in DLog with these, you should be doing the opposite, pulling the shadows and midtones lower.

Also, as with most cameras, the Blue channel is the noisiest of the 3, and I've seen several LUTS (arri's Alexa 709 LUT in particular) that seem to be applying significant gain to the blue channel resulting in significant noise in skies. By nature, the Raw Footage SHOULD have some noise, which is generally quite easy to handle with noise reduction. I process my CDNGs in ACR and it's a simple task. Using Resolve should be similarly capable.

thanks for the feedback guys, appreciate your thoughts too barry.
As it stands I am unsure wether the white and black pixels flashing is normal or due to a faulty sensor of the X5S,
Keep in mind that these ONLY show up when recording RAW, since by shooting in 4K already, the image is "blurred" in comparison to the raw video and these pixels disappear.

I read that DJI would be releasing some sort of tutorial soon, I hope this happens because it would help a lot of people I am sure.
Yet to figure out whether my X5S  is  malfunctioning....

Edit:
I have spoken to support both online and on the phone. They said that if I am shooting in Auto mode, automatic exposure, this problem should not be showing up. The fact that it is means the camera is most likely not working correctly.
I have refreshed the firmware of the drone prior to the below re-test according to advice by support.

New Test Shot, low light, auto exposure, DLOG, Cinema DNG 5.2K, Linear to Rec709 conversion, Davinci Resolve:
https://ibb.co/e0X0Qk

New Test Shot with Cap on. same settings as above:
(using 2.4 Gamma) https://ibb.co/gd4KJ5
Could anyone try what happens when you record with the cap on, then load the Cinema DNG files into Davinci and choose these settings:


I know that this is the wrong gamma setting, but it bring out the worst in the image. Does anyone's footage turn into what you see here above?

(Using Linear to Rec709 conversion)
https://ibb.co/gjdeJ5


(Using Blackmagic Film Gamma)
https://ibb.co/k4pmy5

The Blackmagic Film Gamma almost entirely removes the noise, however it is a very flat profile, so as soon as you grade it the noise returns.