Blue color cast in outer perimeter of still photos

brianmatiash · Jan 2, 2017

Hey there, everyone. I'm new to this forum and a new Mavic Pro owner, as well! I have a question that I'm hoping you can help with.

Yesterday, I took my Mavic Pro on a snowshoeing hike near Mt. Saint Helens and flew it for about 45 min. It flew beautifully although I did get a cold temperature warning. Still, that did not seem to affect flight or capture. However, as I began working on some of the stills, I quickly noticed that every photo has a distinct blue cast vignette with the center of the frame being fine (or what it should look like to me).

Has anyone experienced this? Could it be a symptom of shooting in cold weather (it was around 28-30 degrees Fahrenheit)? I'm embedding three sample photos. All I did in post was correct for tone. No color/white balance adjustments were made and all three jpegs were exported from native DNGs.

Here's a quick export from one of the videos I recorded. From what I can tell, it also has a blue cast. I am not sure if it's the way the light is bouncing off of the snow (it was totally overcast) or, again, because of the cold weather... or it's a defect.

Thanks again for any help you can provide! I really appreciate it!

Best,

Brian

Rule303 · Jan 11, 2017

I took my first flights today (coincidentally also in SW Washington, and also in the snow) and I have exactly the same issue.

Not as artsy of a picture, since it was more about the flight test than the camera work:

Let me know if you figure anything out, and I'll do the same.

Kilrah · Jan 11, 2017

All Mavics are that way as far as I can tell but it isn't really noticeable on usual subjects, it's just the completely white scenery that makes it pop out so obviously.

brianmatiash · Jan 11, 2017

Rule303 said:
I took my first flights today (coincidentally also in SW Washington, and also in the snow) and I have exactly the same issue.

Not as artsy of a picture, since it was more about the flight test than the camera work:
View attachment 3963

Let me know if you figure anything out, and I'll do the same.

Yup - it looks like you have the exact same issue as me. I ended up contacting DJI Support and they advised me to send the drone in for repair. According to the UPS Tracking Label they provided, it should deliver back to them today. I'm hoping they're able to resolve it. I also posted the same issue on the DJI forum and several others chimed in with the same issue. So, the good news is that it doesn't seem to be an anomaly. My hope is that there is a clear resolution here. I'll update when I get the unit returned back and tested.

Kilrah · Jan 11, 2017

I doubt there will be any difference, but I think it's the first time someone returns it specifically for this reason so it will be interesting to know! Be sure to fly in the same conditions once you get it back.

brianmatiash · Jan 11, 2017

Kilrah said:
I doubt there will be any difference, but I think it's the first time someone returns it specifically for this reason so it will be interesting to know! Be sure to fly in the same conditions once you get it back.

We just got about 10" of snow in Portland, so if it gets returned soon, that won't be a problem!

Rule303 · Jan 11, 2017

The results shared on the DJI forum aren't encouraging on this problem:
Red Hot spot in the center of my camera

nzgreen · Jan 11, 2017

Kilrah said:
All Mavics are that way as far as I can tell but it isn't really noticeable on usual subjects, it's just the completely white scenery that makes it pop out so obviously.

Not just in snow unfortunately. I wish I knew why. I see lots of other people's footage with no sign of this discoloration....

AAPhoto · Jan 11, 2017

This is a common issue and it has been reported to DJI in hopes that a firmware update will fix it. It's actually a green color cast in the center of the image (as opposed to blue around the edges).

Was auto white balance being used? If so, cameras tend to make snow look more blue than it is. This is because cameras set to auto white balance try to make an entire scene's colors average out to a 50℅ gray color. When they see pure white, such as a snowy scene, they darken it to bring it back down to 50% gray. This can be controlled by raising the exposure (use the histogram to judge how high you need to increase it) and to fix the color, adjust your exposure to something warmer, like "daylight" or "shade" or using a custom kelvin temperature.

The green color cast in the center can be fixed with a radial gradient filter in Lightroom (photos) or Premiere (videos) or similar editing programs.

halley · Jan 11, 2017

nzgreen said:
I see lots of other people's footage with no sign of this discoloration....

The examples you gave still have a strong hot spot in the center. If you can't see it, stand across the room or on your phone screen and look at it again. Sometimes thumbnails show better overall cast than a nicely detailed large screen can.

nzgreen · Jan 12, 2017

AAPhoto said:
This is a common issue and it has been reported to DJI in hopes that a firmware update will fix it. It's actually a green color cast in the center of the image (as opposed to blue around the edges).

Was auto white balance being used? If so, cameras tend to make snow look more blue than it is. This is because cameras set to auto white balance try to make an entire scene's colors average out to a 50℅ gray color. When they see pure white, such as a snowy scene, they darken it to bring it back down to 50% gray. This can be controlled by raising the exposure (use the histogram to judge how high you need to increase it) and to fix the color, adjust your exposure to something warmer, like "daylight" or "shade" or using a custom kelvin temperature.

The green color cast in the center can be fixed with a radial gradient filter in Lightroom (photos) or Premiere (videos) or similar editing programs.

Music to my ears. I'll be using locked in settings from here in. Thanks for your wise words. Have a great weekend.

Sent from my iPhone using MavicPilots

MJSfoto1956 · Jan 13, 2017

Many years ago (i.e. 2004-2009) I had my Canon 20D DSLR modified by removing the IR filter, thereby turning it into an “infrared” camera. One noticeable behavior that was reported on many forums at the time was the appearance of a “hot spot” on images creating with such modified sensors. This hot spot looked just like what you are seeing here on these MP videos and stills. Indeed, on some of my lenses the hotspot was very visible. While with other lenses, much less so.

Note: I’m just putting this out there as another data point — I’m not suggesting that this is what is going on here, but rather the behavior is eerily similar.

YMMV

Michael

maikm · Jan 14, 2017

Copy of my post in the DJI forum:

I'm also seeing the red spot in all my footage and DNG photos. I also bought the Mavic specifically for RAW photography. My Mavic is currently at DJI because of a decentered lens, so I expect the camera will be exchanged, and I'll see. But I expect the hot spot will still be there, because it's a design flaw. Let me explain.

From my 13 years of experience in RAW DSLR photography, including a Nikon D70 modified for IR photography, I think I recognize the effect. It shows up to various degrees depending on the lens used. My guess is we're seeing an infrared hot spot on the Mavic, caused by the combination of the following:
- the IR filter in front of the sensor is probably too weak or has a cut-off wavelength that is too high
- the optical design of the lens emphasizes the center of the image for high wavelengths

The fact that the hot spot does typically not appear in Jpg images proves that DJI is apparently aware of this flaw and adjusted for it in the in-device image processing, but is not able to do the same for video. And as DNG always records the raw sensor data, it can't be fixed for DNG images as well. And that's what we're seeing.

I see two possible fixes:
- DJI has to change everyone's camera against one with either a fixed IR filter, lens, or both
- in the meantime, an additional IR cut-off filter in front of the lens could also help as a temporary workaround

As I said, I don't have my Mavic here at the moment. Can someone test if the camera can see infrared light sources, like from a TV remote? If you point an IR remote at the camera, does it's LED show up with moderate brightness (which would indicate a strong IR filter in front of the sensor), or does it appear completely white (which would indicate a weak IR filter)?

Maik

leesmavic · Jan 14, 2017

maikm said:
Copy of my post in the DJI forum:

I'm also seeing the red spot in all my footage and DNG photos. I also bought the Mavic specifically for RAW photography. My Mavic is currently at DJI because of a decentered lens, so I expect the camera will be exchanged, and I'll see. But I expect the hot spot will still be there, because it's a design flaw. Let me explain.

From my 13 years of experience in RAW DSLR photography, including a Nikon D70 modified for IR photography, I think I recognize the effect. It shows up to various degrees depending on the lens used. My guess is we're seeing an infrared hot spot on the Mavic, caused by the combination of the following:
- the IR filter in front of the sensor is probably too weak or has a cut-off wavelength that is too high
- the optical design of the lens emphasizes the center of the image for high wavelengths

The fact that the hot spot does typically not appear in Jpg images proves that DJI is apparently aware of this flaw and adjusted for it in the in-device image processing, but is not able to do the same for video. And as DNG always records the raw sensor data, it can't be fixed for DNG images as well. And that's what we're seeing.

I see two possible fixes:
- DJI has to change everyone's camera against one with either a fixed IR filter, lens, or both
- in the meantime, an additional IR cut-off filter in front of the lens could also help as a temporary workaround

As I said, I don't have my Mavic here at the moment. Can someone test if the camera can see infrared light sources, like from a TV remote? If you point an IR remote at the camera, does it's LED show up with moderate brightness (which would indicate a strong IR filter in front of the sensor), or does it appear completely white (which would indicate a weak IR filter)?

Maik

I'd say it's white. Not shining, but not dimmed much.

Sent from my Nexus 7 using MavicPilots mobile app

Nyikhmur · Jan 23, 2017

DJI made an official statement here:

Red Hot spot in the center of my camera

maikm · Jan 23, 2017

Although it is a bit worrying to read "DLSR" which does not exist (it's "DSLR"), nor is "micro DSLR" a thing at all since those compact cameras do not contain any mirrors, I thank DJI for offering an official explanation. And it makes sense. I already speculated about infrared influence in this. The statement lets me hope there can be a fix for DNG images, but we probably have to use some sort of filters in postprocessing for the videos in those light situations.

I'm actually ok with that, given that the compactness of the whole drone is it's main feature. This is obviously a tradeoff you have to make.

Nyikhmur · Jan 23, 2017

Hi maikm.

actually their statement is completely what you wrote in your reply to this topic. This also means to me, that the users who are reporting this problem will have no succes if the RMA, am i right? I am no expert but as i understand all mavics have this issue, because of this camera design...

maikm · Jan 23, 2017

Given the current information, an RMA will be unsuccessful in that you won't get a unit back that doesn't have that problem. You might still get a new unit depending on how much of this the DJI support staff knows or understands. Since you might get one with a worse camera (see threads about blurry corner issues), it's probably not a good idea to send you Mavic in for the hotspot issue alone.

I remember Leica having a similar problem once with their M8. They gave every customer a center-graduated screw-on IR filter to fix it. I can see PolarPro stepping in and sell those for $100 each to use in those lighting conditions

deltalimatango · Jan 24, 2017

One very key point mentioned about the Mavic camera, is that it is optimized for day shooting. I have seen many, many, many people complaining that the Mavic is rubbish at night and this is true. It is a consumer drone, optimized for consumer needs.

STimkey · Jan 30, 2017

Hey - new guy here, but I'm having a similar issue. Got the bird in December, and I'm in WNY (work for a snowboard shop/ski resort), so most of my footie is under apocalyptic gray skies. When it's gray sky against snow, I'm getting it. But in good sun/lighting, I'm not picking it up as much. I've attached some photos. Was thinking of sending the bird back, but I'm not going to now. Just need to figure a way around it (just ordered a couple filters, I'll post up when they come in and I get content)

Thank you!