Dead Pixel Remapping.

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Sean Buffini

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Dead Pixel Remapping.

PostTue Sep 19, 2017 1:06 am

Hi All!
Hope this is the right place to post this...

I'm currently on my 4th Ursa Mini 4.6k due to the previous 3 having faults. Each Time I RMA the camera they just send me a new one. 2 out of the previous 3 RMAs were because of 'Dead','Stuck' or 'Hot' Pixels on the sensor. Now I've just discovered that my current Ursa has developed a Stuck Pixel.

I'm at the point of just accepting that I will have to use the 'Dead Pixel Fixer' tool in resolve for every shot but other cameras like the Canon DSLRs and Sony A7SII have in camera Dead Pixel Remapping where the camera locates faulty Pixels and replaces the information from that pixel with the information from the surrounding pixels.

It doesn't seem like a particularly intensive thing to include in the next firmware update. The process could be triggered manually in-Camera with the Black Shade Calibration.
I think it would save Blackmagic a lot of money rather than just sending out new cameras.

Let me know what you guys think, and let me if the Research and Development team at Blackmagic have a suggestion box box! :D

(I know some of you will be wondering, But I have no idea how I've managed to get so many cameras with faulty pixels in a row. I've researched into this extensively and I cannot figure out whats caused them in my particular situation. My Current camera was tested by a technician before it was sent to me and I believe the sensor was spotless when it first arrived, Leaving me to believe that this is an error that has developed over a very shot space of time.)
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Re: Dead Pixel Remapping.

PostWed Sep 20, 2017 8:41 pm

Four new cameras with dead pixels either as delivered or shortly afterwards. Is it possible there is something in your environment contributing to this? Has BMD tried to go down that avenue. Carpets on the floor in an extremely dry air causing little static shocks? I don’t really know, but it might be something. Anatoly, what would a physicist think?


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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 12:30 am

Did you check for radioactivity? No, seriously.
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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 2:20 am

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 4:22 am

That’s it! Cut back on those interviews with Rocket Man and his guided tours of the WMD plants.


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Anatoly Mashanov

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 11:13 am

I've heard that the most frequent external cause of sensor fault is shooting of mass shows with laser effects or similar scenes with laser rays. The radiation also could influence the sensor but the effects are mostly temporary, and too much radiation is needed for permanent damage.
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Rakesh Malik

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 11:50 am

I find the cosmic ray explanation to be pretty unlikely. They don't interact with matter much, to such ab extent that they're actually rather difficult to detect even with specially designed detectors.

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 12:58 pm

Rakesh Malik wrote:I find the cosmic ray explanation to be pretty unlikely. They don't interact with matter much, to such ab extent that they're actually rather difficult to detect even with specially designed detectors.




COSMIC RADIATION can indeed damage sensors and the end result is dead pixels. There has long been a correlation between airline travel and increased sensor issues. When I worked for a rental company they always transported their sensor based cameras where possible by road rather than air between their multiple offices.

https://ntrs.nasa.gov/archive/nasa/casi ... 022613.pdf

"The Effects of Radiation on Imagery Sensors in Space
Recent experience using high definition video on the International Space Station reveals camera
pixel degradation due to particle radiation to be a much more significant problem with high
definition cameras than with standard definition video. Although it may at first appear that
increased pixel density on the imager is the logical explanation for this, the ISS implementations
of high definition suggest a more complex causal and mediating factor mix. The degree of
damage seems to vary from one type of camera to another, and this variation prompts a
reconsideration of the possible factors in pixel loss, such as imager size, number of pixels, pixel
aperture ratio, imager type (CCD or CMOS), method of error correction/concealment, and the
method of compression used for recording or transmission. The problem of imager pixel loss due
to particle radiation is not limited to out-of-atmosphere applications. Since particle radiation
increases with altitude, it is not surprising to find anecdotal evidence that video cameras subject
to many hours of airline travel show an increased incidence of pixel loss. This is even evident in
some standard definition video applications, and pixel loss due to particle radiation only stands to
become a more salient issue considering the continued diffusion of high definition video cameras
in the marketplace. "

And

From https://www.nasa.gov/mission_pages/stat ... s/974.html

"The experiment compares the Panasonic camera’s metal-oxide semiconductor (MOS) sensor to other charge-coupled device (CCD) cameras. These are two different ways to turn light into an electric charge, which converts visual images into digital information. CCD sensors are common, but they are highly susceptible to damage from radiation in space. The experiment tests how well MOS sensors withstand that radiation."

and

https://www.nasa.gov/mission_pages/stat ... s/124.html

"Matritsa-Z1 (Matrix-1) examines the degradation of charged-coupled devices (CCD) located in high-definition video (HDV) camcorders."

and

""In the case of HD Camcorders, the CCD chips rapidly
deteriorate under bombardment from cosmic rays and other types of space radiation. In on-orbit tests, the cameras lose between 5 and 15 pixels per day..... .....Solar storms can dramatically increase the amount of radiation to which the cameras are exposed. Shielding must provide protection from space radiation or cameras must replaced every 50 - 90 days."

There are many ways that OVER TIME Sensors get more dead pixels. So while yes, you can start off with a good sensor, over time, depending on its operations use, you can pick up more and more dead pixels. No sensor is manufactured perfectly either, they usually get installed with some dead pixels in every camera.

JB

EDIT

Also
http://www.tested.com/science/space/455 ... ors-space/
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Gene Kochanowsky

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 1:16 pm

Some homes have high radon levels from construction materials and the land the home is built on. If you are really concerned about radiation damage you could always store and transport the camera in a lead lined box. Radiation damage to electrical components is enough of an issue that the military specs radiation hardened parts for devices that may be exposed to elevated levels.

If N. Korea tests an H bomb in the pacific expect more hot pixels.

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 1:23 pm

Gene Kochanowsky wrote:Some homes have high radon levels from construction materials and the land the home is built on. If you are really concerned about radiation damage you could always store and transport the camera in a lead lined box.



I don't think lead works for sensors because the energy of radiation they are affected by isn't stopped by LEAD. More like a 9 foot concrete wall.

Or the earth's atmosphere.

Makes you realise how precarious and fragile life is on this little planet.

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 1:44 pm

It takes about 8" of concrete to produce an equivalent absorbing effect of 1" of lead. But the problem with concrete is that depending on the source materials, it can have a significant background radiation as opposed to lead. Concrete can emit radon gas as well as gamma and beta radiation. You just don't know where the base materials came from. My ex wife used to be a radiation control officer for the state, she used to tell me horror stories about people being exposed to lethal levels of radiation in apparently innocuous circumstances.

Damage is a statistical event, and the odds of damage go up as a product of time, radiation and sensitivity to damage.
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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 2:10 pm

The point I understand is that lead doesn't work for the protection of a sensor from the type of radiation that causes it to degrade.

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Re: Dead Pixel Remapping.

PostFri Sep 22, 2017 3:02 pm

John, all materials have some cross section for absorbing radiation of any kind, including your sensor (which is the problem) or even lead. Some more than others. Lead is better than concrete. Especially if the concrete is also an emitter. You can think of it as photographic exposure. If you half the light, it takes twice the time to properly expose. So if you can place materials that half the radiation around your sensor then it will take twice as long to develop an equivalent number of hot pixels. Lead is better at absorbing some kinds of radiation than others, but it will attenuate all kinds of radiation, including neutrinos. Maybe by an indiscernible amount, but it does not have zero cross section for any kind of radiation.

John you may be talking about this. Cosmic ray collisions often cause a cascade shower of byproducts, thin shielding may be more destructive than no shielding at all. So if you are gonna shield, make it at least thick enough to absorb most of the cascade.

This is an issue in interplanetary spacecraft design. A few mm of aluminum may be more hazardous than no aluminum at all. Assuming we could all breath space.
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Re: Dead Pixel Remapping.

PostSat Sep 23, 2017 1:02 pm

Rakesh Malik wrote:I find the cosmic ray explanation to be pretty unlikely. They don't interact with matter much, to such ab extent that they're actually rather difficult to detect even with specially designed detectors.

They DO interact with sensors, you could observe a bright flash in the footage if it occurs and it is how the silicon radiation detectors work. But I doubt that the single cosmic ray particle could irreversibly damage the sensor.

In LHC the VELO detector is basically a set of silicon plates around the collision tube where the hadrons collide and it feels every collision occurring inside LHCb. But the replacement of the detector still is not needed after years of work, and the spare sits idly in LHC museum.

https://lhcb-public.web.cern.ch/lhcb-pu ... LO-en.html

Also, Radon is not harmful for sensors. It produces alpha particles that cannot penetrate a sealed sensor package.

John you may be talking about this. Cosmic ray collisions often cause a cascade shower of byproducts, thin shielding may be more destructive than no shielding at all. So if you are gonna shield, make it at least thick enough to absorb most of the cascade.

I think it's not the case. The particles collide somewhere high in the sky and produce secondary showers covering some kilometers but their energy is much lower. Don't forget that an atmosphere is equivalent to 10 meters of water.
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Re: Dead Pixel Remapping.

PostSat Sep 23, 2017 3:40 pm

Anatoly Mashanov wrote:
Rakesh Malik wrote:I find the cosmic ray explanation to be pretty unlikely. They don't interact with matter much, to such ab extent that they're actually rather difficult to detect even with specially designed detectors.

They DO interact with sensors, you could observe a bright flash in the footage if it occurs and it is how the silicon radiation detectors work. But I doubt that the single cosmic ray particle could irreversibly damage the sensor.

In LHC the VELO detector is basically a set of silicon plates around the collision tube where the hadrons collide and it feels every collision occurring inside LHCb. But the replacement of the detector still is not needed after years of work, and the spare sits idly in LHC museum.

https://lhcb-public.web.cern.ch/lhcb-pu ... LO-en.html


I would expect a sensor designed for those conditions would be able to handle it. It is also considerably larger than a standard image sensor. Also the silicon component in the path of packet collision secondary particles has minimal to no circuitry. There is nothing to damage. Lattice dislocations in the silicon do not degrade its detection performance.



The smaller the circuit feature on a substrate the less it takes to damage it.
https://www.nikhef.nl/pub/departments/m ... esign.html
Also, Radon is not harmful for sensors. It produces alpha particles that cannot penetrate a sealed sensor package.


Radon is a gas and diffuses everywhere. If concentrations are high enough in the camera's environment the sensor will be exposed to some level. Of course keeping the camera in a sealed container will reduce this risk. But if you stick the camera on a shelf the sensor could be exposed if radon levels are high enough.
John you may be talking about this. Cosmic ray collisions often cause a cascade shower of byproducts, thin shielding may be more destructive than no shielding at all. So if you are gonna shield, make it at least thick enough to absorb most of the cascade.

I think it's not the case. The particles collide somewhere high in the sky and produce secondary showers covering some kilometers but their energy is much lower. Don't forget that an atmosphere is equivalent to 10 meters of water.


Collision is a statistical process, so the number of cosmic rays at sea level is less than 10% of levels in near earth space, it is not zero. Also those cosmic rays that collide with the atmosphere produce a shower of secondary particles, many of them produce hadrons which have sufficient energy to damage a small circuit structure on a substrate as would be found on a modern commercial image sensor. From a particle's point of view an atom is mostly empty space, they have to collide with a nuclei in order to be affected.

Now admittedly all these sources of radioactivity are usually small, but damage is cumulative and given enough time and exposure there will be damage.
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Re: Dead Pixel Remapping.

PostSat Sep 23, 2017 8:32 pm

I think we should present this forum thread at a TED Talk. It’s The Right Stuff. Thanks for the narrative.


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Re: Dead Pixel Remapping.

PostSat Sep 23, 2017 9:35 pm

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Re: Dead Pixel Remapping.

PostSat Sep 23, 2017 9:48 pm

So the sensor has a number of design features to improve its ability to withstand the environmental radiation. It's impressive that they expect it to last 12 years before it starts degrading. The sensor is quite a feat of engineering. But it is really not comparable in any way with a conventional image sensor. This thing was designed to detect the vortex of the primary and secondary collisions in three dimensions.

LHCbVertexDetector&BeetleChip.png
Radiation Hardness Test
LHCbVertexDetector&BeetleChip.png (58.46 KiB) Viewed 9394 times
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Re: Dead Pixel Remapping.

PostSat Sep 23, 2017 10:40 pm

Anatoly is indeed our resident physicist.


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Re: Dead Pixel Remapping.

PostSun Sep 24, 2017 1:16 am

In a previous life I was a physicist. I designed and constructed a heavy ion implanter as part of the experimental apparatus for my PhD thesis.
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Re: Dead Pixel Remapping.

PostSun Sep 24, 2017 6:11 am

Superb, Gene. Thanks for sharing. In a previous life I studied Physics and Cosmology is a true love.


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Re: Dead Pixel Remapping.

PostSun Sep 24, 2017 12:41 pm

Rick, are there a lot of physicists on this forum?
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Re: Dead Pixel Remapping.

PostSun Sep 24, 2017 9:40 pm

Back to topic...

The BMD cameras DO have a pixel remapping function. If they didn't then everyone would be seeing a lot more dead pixels.

It's just not a user activated function, it's automated. Same as Alexa, which also has no user accessible function for pixel re-mapping.

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Re: Dead Pixel Remapping.

PostSun Sep 24, 2017 9:56 pm

You can force the Sony Alpha series cameras to pixel remap by advancing the date and doing a power cycle, I had a stuck pixel on my a6300 recently and it sorted it right out.

Might be worth a try.
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Re: Dead Pixel Remapping.

PostSun Sep 24, 2017 11:29 pm

Same here, that trick fixed a bright red one in my A7S.
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Re: Dead Pixel Remapping.

PostMon Sep 25, 2017 2:02 am

James Alexander Barnett wrote:Might be worth a try.


I believe it happens on a BMD camera when you power cycle the camera. Perhaps Tim or Hook can enlighten us if that's not correct.

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Re: Dead Pixel Remapping.

PostMon Sep 25, 2017 4:25 am

I just purchased a used BMPCC that has a bright white stuck pixel, and have tried downgrading then upgrading firmware but the spot's still there. Any tips on triggering a remap would be appreciated.

The Resolve Dead Pixel Mapper deals with it, but I'd prefer to not have to run it on every clip…
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Re: Dead Pixel Remapping.

PostSun Oct 01, 2017 5:39 pm

Thanks for all the info guys! Lots of great stuff here!

I'm currently in contact with BMDs Support team and it looks like I'm going to have to ship this camera off too!

John Brawley wrote:
James Alexander Barnett wrote:Might be worth a try.


I believe it happens on a BMD camera when you power cycle the camera. Perhaps Tim or Hook can enlighten us if that's not correct.

JB


By 'power cycle' do you mean turning the camera off and on again? 'Cause believe me I've tried :lol:
I've also tried black shading and rolling back firmware and updating again.

Uli Plank wrote:Did you check for radioactivity? No, seriously.


I live in Dublin, Ireland. So I believe the background radiation here is relatively low.
Also, I haven't noticed any pixel issues on any of my other cameras including my BMPCC. So unless the Ursa Mini 4.6k is especially sensitive I can't imagine it's just the ambient radioactivity. But It's possible.

rick.lang wrote:Four new cameras with dead pixels either as delivered or shortly afterwards. Is it possible there is something in your environment contributing to this? Has BMD tried to go down that avenue. Carpets on the floor in an extremely dry air causing little static shocks? I don’t really know, but it might be something. Anatoly, what would a physicist think?


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I haven't thought about that before. It's a good lead!
The Camera body lives in a Pelicase 1510. Often when it's built and being moved around on location it's in a Panavision Large AC bag. Sometimes I keep it on my wooden desk. I have wooden flooring and no curtains (It's a boring room) I'm not sure any of the places it's kept would generate static.
After seeing your post I asked Blackmagic support if anything environmental could be causing it. They Said...

"There aren't any external factors we are aware of that would typically cause this behaviour, so it would appear that you have been quite unfortunate"

...So It's possible I'm just unlucky.

Paul Kapp wrote:Do you do a lot of air travel with your cameras?
A common cause of dead pixels is cosmic rays striking the sensor. This radiation is more prevalent at high altitudes.
True story.


I've never taken any of my Ursa's on a plane. however, I presume they are transported to me via a short plane flight from England to Ireland, As the Blackmagic Support HQ for my region is in the UK.
So It's possible.
The flying/Gamma ray/Pixel thing is something I think about a lot. I've taken other cameras on many flights and have never noticed a problem on them, Including my other Blackmagic camera, The BMPCC. I heard It effects CCD sensors more than CMOS sensors. I've also heard it's just fear mongering from Kodak. But from my understanding of the issue, a single short flight shouldn't be enough to cause a faulty pixels in every camera. It's possible, but not probable.

Some great investigative work and research here guys! Thanks! :D :D :D
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Re: Dead Pixel Remapping.

PostSun Aug 12, 2018 5:43 pm

Just discovered a hot red stuck pixel on my URSA Mini 4.6K. Didn’t notice it when working in colour but I decided to go with zero saturation and it shows clearly. Went to the camera with lens cap on and it shows bright red. Just before my shoot on Friday I did a sensor recalibration. Never saw the stuck pixel before then. Did a power cycle and recalibration now and still stuck.


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Re: Dead Pixel Remapping.

PostMon Aug 13, 2018 11:55 am

Since this is a bit off topic and we're discussing the effects of radiation on sensors I thought I might chime in...
I'm a radiologist at Lund University Hospital. We have a radiation therapy department where there's several Varian linear accelerators. As these are used to treat tumors with high doses of radiation, nobody but the patient can be in the treatment room when the radiation is on. The treatment rooms has some _really_ thick and dense walls, I'm not sure if there's lead in them or just lots of concrete. To be able to watch the patient during the treatment, there's CCTV cameras in the treatment rooms and monitors in the control rooms. I noticed that the picture from these cameras was pretty messed up and asked on of the physicists if it was caused by radiation damaging the sensors, and he confirmed that the sensors in these cameras degraded significantly from the radiation.
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Re: Dead Pixel Remapping.

PostSun Aug 29, 2021 2:24 pm

Mattias Kristiansson wrote:Since this is a bit off topic and we're discussing the effects of radiation on sensors I thought I might chime in...
I'm a radiologist at Lund University Hospital. We have a radiation therapy department where there's several Varian linear accelerators. As these are used to treat tumors with high doses of radiation, nobody but the patient can be in the treatment room when the radiation is on. The treatment rooms has some _really_ thick and dense walls, I'm not sure if there's lead in them or just lots of concrete. To be able to watch the patient during the treatment, there's CCTV cameras in the treatment rooms and monitors in the control rooms. I noticed that the picture from these cameras was pretty messed up and asked on of the physicists if it was caused by radiation damaging the sensors, and he confirmed that the sensors in these cameras degraded significantly from the radiation.


That's really really interesting! Thank you for sharing!
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Re: Dead Pixel Remapping.

PostSun Aug 29, 2021 3:49 pm

@ Sean: Do you have any vintage lenses for your cameras? A few are radioactive.
I doubt that a short flight is doing the damage. I had my UMP 4.6K with me on several long distance ones.
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Re: Dead Pixel Remapping.

PostSun Aug 29, 2021 7:20 pm

It’s 100% true that radiation is a cause of dead pixels.

Cosmic radiation over time will kill pixels.

If your sensor flys a lot, it’s more likely to get more radiation (less atmosphere) and thus, more dead pixels. It’s routine for the big camera rental companies to try and NOT fly but road freight their cameras when they ship them.

Here’s a pretty good read on it all. This is talking about the camera on the new mars remote, but it’s a really cool read on what’s going on.

https://mastcamz.asu.edu/bad-pixels/

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