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Mavic underexposure artefacts
4772 21 2017-1-24
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ReinisK
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Flight distance : 21946 ft
Latvia
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Hey!

I've had the Mavic for a little more than a week and I'm still testing everything out, including the camera.
A few days ago I came back from a test flight and I found this awful footage -
I didn't expect miracles out of this small camera, but those very blurry dark parts are something I haven't seen before with any camera (I've been working as a camera guy and editor for more than 5 years).
This was shot at 4k 24p, Art -1,-3,-1. Converted to 1080p for youtube, but at 4k it looks the same.
Further tests revealed that the dark parts of the image get very, very compressed. So if you accidently underexpose your shot, it's going to have a LOT less detail.
So the exposure must be spot on every time. This is true about almost any small sensor camera with a compressed codec, but from other cameras I've never seen anything like those blurry artefacts.
Underexposed raw photo files are ok and don't lose detail much. So that makes me think that the image compression processing is set to compress low exposure areas too much. And by that I mean really a LOT, as you can see in the video. The footage is unwatchable (not even talking about "using" it - putting it next to other shots in a video edit).
So what does this mean? It's not just about exposing properly, it's more about high contrast scenes like sunsets, sunrises and probably other scenes.

The compression is so bad, that really it cannot be hidden. I'm not talking about bringing the shadows up to see into them, even bringing them down doesn't hide that blur. So essentially it's a lost shot - a scene which just cannot be shot because of this compression. Like really if I turn the camera that direction, the shot is ruined.

As I said, I haven't seen other small cameras do this, and since the DNG's are alright, it must be a problem that can be fixed with a firmware update. Probably the solution could be decreasing the compression in the darker parts of the image, I really hope it's possible and will be done.

So what about others, has anyone else noticed this? Would be interesting to see some high contrast scenes from other owners.
2017-1-24
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Trent Mavic
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Flight distance : 1098924 ft
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I'm a complete amateur at this and the understanding of cameras but I've also found the same thing with low light... bushes and trees look a complete blur at times!
2017-1-24
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Trent Mavic
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I'm a complete amateur at this and the understanding of cameras but I've also found the same thing with low light... bushes and trees look a complete blur at times!

I also find that, again, at times there are incredible amounts of noise in darker areas of shots.

NOTE: Not a good example! I know this is VERY low light but I've had the same in much brighter situations however this is the only unedited footage I have at the moment...



Again, not a great example but only footage with slight problem, in the darker areas I'm getting quite a bit of noise...
2017-1-24
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Trent Mavic
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Wow... I'm really messing up these replies Anyway, here's the large version of that first photo I was meant to post... (In the bottom right mainly)
2017-1-24
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WolfgangStiller
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I got a lot of noise shooting at 4K as well.  Shooting at lower res (at 100 iso of course), I find much less dark area nose.  Currently I am doing 2.7k but I think the 3280 4k setting may be pretty good as well.
2017-1-24
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D.Walls
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WolfgangStiller Posted at 2017-1-24 07:01
I got a lot of noise shooting at 4K as well.  Shooting at lower res (at 100 iso of course), I find much less dark area nose.  Currently I am doing 2.7k but I think the 3280 4k setting may be pretty good as well.

This also happens to me, I posted a thread about it a week ago or so. I think the problem occurs when shooting at negative sharpness. This shouldn't be a problem at all, but in the case of the Mavic it messes the shadows a lot, and they become blurry. Probably because of the codec but that doesn't make much sense since increasing the sharpness gets that detail back (at a cost of greater noise), which means the codec can handle that amount of detail. I'm a bit disapointed about this, maybe if more people reports this issue we can get DJI checking the problem.
2017-1-24
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ReinisK
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Trent Mavic, are those  photos or screenshots from video?
The sunset one definitely looks like a screenshot and has that blurry thing I'm talking about. The bright one looks fine though.
Having some noise even at iso 100 in the dark areas is fine, though, if you shoot at somewhat flat picture profile. Many cameras have that noise, especially the smaller cameras like phone and action cameras. Also, if you shoot at higher ISOs, it's normal to loose some detail and gain noise, that's what smaller cameras do. Night videos can be softer.
My example was shot at ISO 100, so there's no way it could have lost that detail because of too high ISO.
D.Walls - thanks for the reply, I'll do some tests tomorrow. Really hope that this could be a solution.
2017-1-24
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ReinisK
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I did a few more tests today and what D.Walls said is partly true. The less sharpening the more blurry shadows become.
Just now I did a very surprising test.
First shot is ISO 100, Art, 0, -3, -1. For the second shot I set sharpening to +3, so it's ISO 100, Art, +3,-3,-1.
That's some incredible difference. In the first shot, the shadows are really blurry (less blurry than they would be with a negative sharpness, of course), but when I set sharpening to +3 it reveals so much detail compared to the first one. There is no way the first shot can be sharpened in post to gain the details of the second one.



It seems that the sharpening parameter is also a noise reduction parameter. The higher sharpen value, the less noise reduction in the shadows.
If I try to use noise reduction on the +3 sharpen video, it gains a very similar look to 0 sharpen.
On the other hand +3 sharpening at daytime probably looks like crap, though I haven't tried it yet.

The best would be if DJI intruduced a separate sharpening and noise reduction controls. That would be a huge benefit to the videos Mavic can produce.

Would be very interesting to hear what DJI team says about this.
2017-1-25
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Ex Machina
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I'm guessing that's not noise-reduction in play, rather the way video compression works -- where the codec doesn't see detail, it tosses information. Add more detail via sharpening and the codec has more to work with frame-to-frame and doesn't toss as much data. The higher the sharpening, the more obvious the noise. You see this on cameras with much larger sensors as well.

You could test this by shooting RAW photos and applying your own sharpening/noise reduction values. You won't see the video interframe compression artifacts but you can examine the limits of the sensor in low light.

Ultimately I think just as with dedicated cameras, if you want higher-quality video in lower light, you'll need a larger sensor with more dynamic range and concurrent cost.

2017-1-25
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ReinisK
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I was thinking exactly the same - sharpening gives more information before the compression and encoding part, so that's why there would better details.
I took some Raw photos as well there and without any post sharpening or noise reduction they look very similar to the +3 sharpen video.
In some places the contrast is ok, but 0 sharpen still makes it blurry (trees on a lighter background for example). That makes me think it's some kind of noise reduction.
Plus it's really good at reducing noise, and I haven't seen any compression reducing noise that good, it always leaves some moving particles, but here it's very smooth.
2017-1-25
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RitterRunkel
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ReinisK Posted at 2017-1-25 07:53
I was thinking exactly the same - sharpening gives more information before the compression and encoding part, so that's why there would better details.
I took some Raw photos as well there and without any post sharpening or noise reduction they look very similar to the +3 sharpen video.
In some places the contrast is ok, but 0 sharpen still makes it blurry (trees on a lighter background for example). That makes me think it's some kind of noise reduction.

I'm also not sure, if this blur in dark areas is only due to compression. I captured foggy scenes with 24fps only and I didn't get the impression that the 60K bitrate is really used. If there are almost no image areas with fine detail, the codec should have enough bits left to leave some details in the darker areas or areas with less contrast.

More sharpness is no solution since brighter image parts with contrast will suffer (halos, artefacts, ...).

Anyone from DJI willing to explain? I guess many of us would like to see a preset with more natural detail .... leaving some luminance noise in homogenous areas with less blur.

It's the same with the JPEG photographs versus RAW. But here I can use RAW ...
2017-2-3
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fans8606e081
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The pictures i get with negative sharpness are terrible. Trees are just mush. 60 Mbps should do better than this. Also if it was just the data rate it should get better with less resolution which is not the case.
There has to be something wrong with the encoding process. I do video encoding since over 15 years and i've never seen "encoding artifacts" like these. Those look more like when you apply way to much noise reduction. As seen in ReinisK's Video above. The change you get from 0 to +3 is beyond normal camera behaviour. Just let's hope this gets sorted out.
2017-2-5
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fans8606e081
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UPDATE: After some testing it looks like negative values don't get rid of edge sharpening like one would expect but in fact it's noise reduction kicking in.

My conclusion:
sharpness at -1 - you'd get slight noise reduction but still acceptable for people who can't or wont denoise in post.
sharpness at -2&-3 - will give you severe oil painting effect
sharpness at 0 - is ok for most cases but there will be some noise. (i'll use this and denoise in post)
sharpness at +1 - has more noise but also more details in the shadows. (i'll use this with denoise inpost when details in the shadows matter)
sharpness at +2&3 - has way to much edge sharpening imho.

it would be interesting if this is consistent in all mavic's or if there are differences.
2017-2-6
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fans8606e081
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Just back from another test. While sun was up, 0 was the best sharpness setting in terms of noise vs artifacts.
But as soon as light started dying trees in shadow started looking like there's way to much noise reduction.The same you'll get at sharpness -3. Changing to +1 introduced a bit of noise but trees looked ok until light was gone.
I'm more and more under the impression that the mavic doesn't do any sharpening at all but just more ore less noise reduction.

So i'll stick to +1 from now on and do the NR in post where i have much more control about it.

2017-2-6
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ReinisK
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Nice to see other people thinking about this.
I've also done some recent tests, and I've found that +1 sharpness seems to be without any noise reduction. If sharpness is set to 0, you can immediately see the difference (blurry, NR'ed shadows) in shadow detail against +1, but yes - less noise.
My tests were done at ISO 100, 400 and 800, Art profile, contrast -1, saturation -1.
+2 and +3 at least from my tests seem to just increase noise a little bit, but not gain any details in shadows. These values don't seem to give any positive result, since detail seems exactly like with +1, but a bit more noise.
At ISO 800 though, I would choose 0 sharpness even if I plan to use NR in post. Probably because with 0 sharpness the internal NR gets less compressed image to work with whereas with +1 sharpness and post NR, there isn't a fine noise pattern, but rather some compression artefacts too, which is harder for NR to remove.

I'll probably use +1 too, but actually I don't like the image I get with it 100%. It can seem a little too grainy then even when downscaled to 1080p. But it's winter here, so I haven't seen very colorful scenes from the Mavic yet.

Would be nice to hear some other test results.
2017-2-7
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Ex Machina
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Interesting results. I've been frame grabbing video to get stills and to my eye they look sharpened at the 0 setting; this becomes most evident when you autolevel the frame grab -- I've actually considered shooting at -1 so I can better manage sharpness and levels in post.
2017-2-7
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ReinisK
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To me they actually look too sharpened, too. I would prefer to shoot at -1, but I don't like loosing the shadow detail because of that NR.
Highlights definitely look better to me with negative sharpness, but I can't get over the blurry shadows. Really, don't know what to do, have to find a way to make the highlights better looking in post with the +1 sharpness setting.
Of course, the best would be if DJI fixed it by introducing different indicators for sharpness and NR, if I'm guessing the situation right.
2017-2-7
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CaptainFantasti
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Ex Machina Posted at 2017-2-7 08:28
Interesting results. I've been frame grabbing video to get stills and to my eye they look sharpened at the 0 setting; this becomes most evident when you autolevel the frame grab -- I've actually considered shooting at -1 so I can better manage sharpness and levels in post.

Imho there is not less sharpening at -1 but just more NR (wich can look like sharpening since the areas before the edges become more uniform and therefore give you a "clearer" look). The normal softening effect when i dial edge sharpening down in every other video camera i've ever used ist just not there. You see this with -2 in perfect lighting it looking just as sharp as 0.

Of corse under optimal lighting conditions 0&even-1&-2 or totally ok and can lead to great results as you can see in various clips online. My problem is that when i've done a shot for a client i cant wait to be back at the office to find out if its usable or just mush. So +1 with NR in post it is for me. I'll post some examples later.
2017-2-7
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M Stuart K
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ReinisK Posted at 2017-2-7 08:46
To me they actually look too sharpened, too. I would prefer to shoot at -1, but I don't like loosing the shadow detail because of that NR.
Highlights definitely look better to me with negative sharpness, but I can't get over the blurry shadows. Really, don't know what to do, have to find a way to make the highlights better looking in post with the +1 sharpness setting.
Of course, the best would be if DJI fixed it by introducing different indicators for sharpness and NR, if I'm guessing the situation right.

I do not subscribe to have near the knowledge of you guys about photography but I do enjoy reading your comments in attempts to better understand.  The question that bothers me is this: Somewhere I read that the camera on the Mavic was the same as the P4.  I have both drones and have been shooting video and taking pictures with my P4 since I purchased it last March.  I don't mind admitting; with my P4 I use auto mode and the thing just rocks on both pictures and video but this Mavic-not so much.  It takes too much work to get a decent picture or video with this thing, so my guess is these cameras are really not the same?
2017-2-7
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Ex Machina
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M Stuart K Posted at 2017-2-7 14:02
I do not subscribe to have near the knowledge of you guys about photography but I do enjoy reading your comments in attempts to better understand.  The question that bothers me is this: Somewhere I read that the camera on the Mavic was the same as the P4.  I have both drones and have been shooting video and taking pictures with my P4 since I purchased it last March.  I don't mind admitting; with my P4 I use auto mode and the thing just rocks on both pictures and video but this Mavic-not so much.  It takes too much work to get a decent picture or video with this thing, so my guess is these cameras are really not the same?

My understanding is the cameras are not the same. In large part the specs are similar, though, which may have lead people to make such an assumption.
2017-3-9
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fans980d1304
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This thread is spot on. I'm afraid DJI may nota dress the issue since many Mavic users wouldn't be able to explain the problem as accurately as you guys have. I've been scratching my head about this all week and this nails it. going to test +1 and some type of blur or NR in post. Strange workflow for sure.
2017-4-7
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VAS67
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The thing I find frustrating is that the Mavic was designed to be quick, easy, and efficient, which it is in terms of portability and actually getting it up in the air.
However the camera requires serious work and effort to get the desired acceptable footage, a fair bit of user photography knowledge is required to be able to understand how to achieve this.
So this kind of goes against the grain of what the Mavic actually stands for, everybody wants quick and easy but nobody wants cr@p footage. The problem here is cr@p footage is easily (accidentally) achieved with such a finicky camera. For the past month I've been carrying out various camera setup configurations in preparation for a road trip around the Swiss Alps at the end of this month, I'm really concerned that I'll get cr@p footage and I won't know it until I get back home and analyse it on my PC.

So this is what I've learnt and by no means is this cast in stone, it's just my opinion.
1: Only shoot in 4K if your looking for the absolute best footage achievable, it can be down resolutioned in post if required.
2: Extremely bright days.          -1 0 0   (ND 8 Filter)
3: Cloudy / overcast days.          0 0 0   (ND 4 Filter or no filter depending on light)
4: Fading light                            +1 0 0   ( No Filter)

I have found D-Cinelike to be the best with the above settings.
The ND 16 I've only tried once, the end results were so bad I can't bring myself to try it again, maybe I did something else wrong, I don't know?

If you're at a complete loss with your own setup then try the above and then tweak to your own liking, this should give you a good start though. (Hopefully?)

Ooh, nearly forgot, manual camera settings and really try never to go higher than 100 ISO. At least during normal daylight anyway.
Good footage at dusk is tough, for me it's been a bit of a lottery.
2017-4-8
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