Mavic Air plagued with the center Hot Spot
2555 19 2018-2-15
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exos
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Hi,

After a few researches, I've found that the Mavic Pro has a "center hot spot" issue, where the center of DNG images are warmer in tone, and the edges (circular) are less exposed, kind of a vignetting effect. The Mavic Air has the exact same problem. I have made a develop preset in Acdsee Ultimate to compensate for that, but it's a bit dissapointing to have that kind of problem with a 1k drone. If anybody is interested to get that preset for Acdsee, I will make it available. I have yet to make another preset for Edit mode to compensate for the color shift.

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2018-2-15
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fans356367d4
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I can certainly imagine an image that would better illustrate the effect. Perhaps a cloudy day, looking down on a baseball or football field?
2018-2-15
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exos
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Yeah.. I agree this is not the best example. I'll try to find a better one.
2018-2-15
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exos
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Here is a better example. I still need to work on the radial gradients a little, but that gives you an idea.


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exos
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I think I pretty much nailed it :
Nahhh ... not yet
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exos
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This is really frustrating....
2018-2-15
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exos
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Ok now I think I've got it. I have left the blue-cyan hue to better show the result. But that means yet another step to correct the picture. This is on AWB... only the center portion had the correct white balance...So I guess it's not really a "center hot spot", but rather a "cold blue large vignetting".
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$gambino$
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Seriously? Dont see anything lol...yall complain over the weirdest things smh
2018-2-15
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AM0
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I would also call it a vignetting. This happens with most lenses, some people don't like it and some do :-)
In digital age this is usually corrected in image processing phase inside the device. That's why you can see it only in RAW/DNG images
Sometimes if you have a polarizing filter not adjusted properly you could see something like this happen.
You don't have any polarizing filters in front of your lens?
2018-2-15
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pawel_g
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DJI has a kind of document about that phenomenon which happens when distance from lens to sensor is very small.
In case of Mavic Air I found this spot easily correctable (in Lightroom) as its seems to be purely white balance shift towards corners. So using simple center circular filter with some adjusted WB solves the problem. Of course you have to shoot DNG.

Br, Pawel.
2018-2-16
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Cameleon
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So is this only visible in RAW? Meaning DJI correct this in their "development" to JPG? I'll have to keep an eye out for this as I've only been messing with JPG so far but plan to use RAW when I want "keeper" shots.
2018-2-16
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pawel_g
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Cameleon Posted at 2018-2-16 00:52
So is this only visible in RAW? Meaning DJI correct this in their "development" to JPG? I'll have to keep an eye out for this as I've only been messing with JPG so far but plan to use RAW when I want "keeper" shots.

Nope. I've written about DNG because correcting WB in JPG almost always finishes with huge quality loss and banding. Of course this is also visible in JPG.

Br, pawel
2018-2-16
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Cameleon
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pawel_g Posted at 2018-2-16 02:14
Nope. I've written about DNG because correcting WB in JPG almost always finishes with huge quality loss and banding. Of course this is also visible in JPG.

Br, pawel

Oh that's bad! I've not noticed that in my images, but then again I've not looked closely. I was expecting that this was a known "characteristic" of the lens/sensor that DJI were correcting in processing. I have had several cameras that correct for lens distortions/vignetting/CA in processing to JPG but leave them uncorrected in RAW/DNG and you have to correct them yourself in post. Really bad if this is left in the DJI defects. Wonder if this is a defect with the model or a quality control issue?
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pawel_g
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I guess its neither defect nor quality control. Laws of physics - if you have such small lens so close to the sensor - that is how light behaves. Of course it would be good if DJI apply some correction in JPG processing (I guess they can do it as they fixed that mostly on Mavic Pro).

It will not be visible in summer conditions where scenes are much more "complex". The snow scenario is the worst.

Br, pawel.
2018-2-16
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Montfrooij
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That is weird indeed.
2018-2-16
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LoSBoL
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If I l look good enough I can see this happening to me to, hoping that this can be fixed with a firmware update.
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exos
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It is NOT visible wih JPEGS. I guess DJI already applies a correction to both video and JPEGS. The pictures I've attached are from DNG's.
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exos
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pawel_g Posted at 2018-2-16 00:28
DJI has a kind of document about that phenomenon which happens when distance from lens to sensor is very small.
In case of Mavic Air I found this spot easily correctable (in Lightroom) as its seems to be purely white balance shift towards corners. So using simple center circular filter with some adjusted WB solves the problem. Of course you have to shoot DNG.

It is not only WB. The exposure also has to be corrected, in my case anyways.
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Montfrooij
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exos Posted at 2018-2-16 06:06
It is NOT visible wih JPEGS. I guess DJI already applies a correction to both video and JPEGS. The pictures I've attached are from DNG's.

That makes sense indeed.
Not visible with JPG.
But it is far from what you would want.
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Cameleon
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exos Posted at 2018-2-16 06:06
It is NOT visible wih JPEGS. I guess DJI already applies a correction to both video and JPEGS. The pictures I've attached are from DNG's.

That makes more sense. Shame the required correction is more than distortion adjustments that are usually required when processing RAW. Makes it a lot more involved to process the RAWs. I will probably save RAWs for real keeper shots that I want printed and on the wall and use built in JPG for posting to Facebook/Insta/etc to save a load of post processing effort every time.
2018-2-16
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