Dead Pixels Show

[Gaetan Boren]

HiI am a casual videographer and have had my EOS 70D for 2 years. I recently noticed 3 spots that are persistent throughout videos, despite changing SD cards, batteries, and wiping the lens. See photo. Does anyone know the cause of these 3 red and blue spots and/or how to fix them? Thank you!

Those appear to be "hot" pixels and typically show up at a higher ISO setting and from the grain and color noise in the example you posted that appears to be shot at high ISO. Try shooting some photographs in a brighter setting at ISO 400 or below (without a long exposure) and see if they disappear from those images.

They typically aren't a big concern with photography because it is easy to map them out if it is just a few at high ISO but video is a different deal. The sensor will heat up more using video (or live view) than it will in typical DSLR use so these hot pixels are more likely when shooting video in a darker setting.

You don't have the same flexibilty in choosing shutter speed for video that you do for stills since you want to avoid choppy motion but going to a slower shutter speed will allow the same exposure at a lower ISO just like it does for stills. In the case of video the mechanical shutter is held open and the shutter speed for video refers to the period of time the sensor is sampling the scene before it is read and refreshed. So you may find a combination of a different frames per second and shutter speed will allow better video quality without overdoing the light.

Others with more experience with video will likely chime in. I shoot very little video with my DSLR bodies and not much so far with the XF-400 camcorder althought that will change when my daughter starts her indoor soccer season next month and I will be dealing with trying to shoot video under horrible indoor lighting conditions.

After doing liquify on a smart object/rasterized layer, there are random dead pixels showing up on the whole image and it stays as it is while saving a jpeg/tiff file. Attached is a screenshot of an area of an image after liquify. Can anyone please suggest a solution for this? I have updated PS, restarted it, worked on a different file but still the issue persists. I am currently on CC 2018. TIA

Thank you for the link. It has happened only after the update and turning off GPU worked but it slows down the whole process. Is there another way to tackle this without affecting the performance? Or do we have to wait for a bug fix update?

I am having this problem even now in 2022. I have checked for dead pixel with black screen and there's no error. Just the images with CC 2020 have this problem after liquify. Can anyone help with this? Do I need to update to 2021?

Do these hot pixels show up in your "normal" images, or is the image above from a long exposure? Many cameras have hot pixels that show up with long exposures. I don't think you should worry about it.

On a more serious note, I would venture to say that a lot of film scanner users would kill just to have to contend with just two hot pixels to remove, instead of dealing with the countless scratches and dust removal.

Well, I wanted to ask. I have never seen a used camera ad (here or on ebay) specifically say "camera has two stuck pixels" -- wanted to know if it's just assumed that a camera will have some, or if people expect that if it doesn't say it, the camera won't have them (and no camera here or on ebay has ever had a stuck pixel). :-)

The stuck pixels are on the image sensor, not the display i.e. every picture (RAW file) has the same pixels stuck on, at the same locations. I'm actually up to four now (two red, two green) after some careful viewing of some dark backgrounds.

Hot pixels are very normal. You maybe use Lightroom that automatically removes hot pixels? I have hot pixels it in Canon D30, 1000D, 7D and 6D. I use Darktable and RawTherapee so I see the hot pixels before I remove them in the software.

Long exposure noise reduction is a dark frame thingy to remove hot pixels. You can do it manually taking a dark frame after your picture and then substract the hot pixels in GIMP/Photoshop. You maybe are thinking of High ISO noise reduction to remove noise?

Stuck pixels always receive power, which results in a colored pixel that shows up in the same spot. The colors can be red, green, blue or any combination. Unlike dead pixels, stuck pixels do not change their color from picture to picture. Stuck pixels are common.

In my 4-shots test (HERE) I can see 20 or 30 dead pixels yet at ISO 100, and many more at ISO 800. Anyway, I can see all these dead pixels ONLY in Bridge, while they disappear in ACR. I tried to explain this difference remembering that ACR should have a sort of dead pixels fixer (even if I didn't suppose it was automatic).

So probably Bridge shows the "truth".

At this point I can choose: "mapping" the sensor's dead pixels with the in-camera manual sensor cleaning method (so keeping the camera with its patchy sensor), or returning the camera to Amazon asking for a replacement.

Before taking a decision, I'd like to know your opinions. Is it normal that a brand new camera has that amount of dead pixels? (Moreover, ACR is not in my workflow, so I can't eventually take advantage of its "corrections".)

Thanks in advance for your help.

There is a free program called "dead pixel test" which you can download from photo freeware net which apparently gives you a count of problem pixels but I have never tried it so can't say if it is any good.

You are worrying too much, the test in the video is flawed, if you carried out the test as shown in the video then you should have got black frames and not the multi-coloured frames that you have shown, even then it is a very poor test and will not show a dead pixel which usually appears as a black spot.

The remapping procedure that they describe is very much open to question, even Canon will tell you that it doesn't work. What happens is that the pixels that seem to be hot/stuck/dead can change position on each shot or even disappear at times and people think they have fixed it when they have done nothing.

When I was starting with photography, I was asked to make some videos and photos of an event. The camera which was doing the filming was pointing at the stage, and my other camera was with me to take some photos. It was my first experience with photographing low-lit locations and with fog and lasers too. The good part is that I've learned quite a lot about how to shoot in such scenarios since, but the camera that was filming was on a tripod, and it was stationary for the whole time, with a wide angle lens to record the entire stage. Thankfully, the low magnification helped minimize the damage.

So, after the event, I've packed back everything and went back home, and to my sad surprise, there was something very strange on the footage, from the middle towards the end. There were some odd, pinkish spots that didn't look like dust spots, but in fact were the dead pixels on that part of the sensor. The laser projector was pointing towards the crowd (literally towards the crowd watching, the light beam moving around, but every now and then, it could reach people's eyes and my camera too). And these dead pixels shows on every photo that I shoot with this camera now, just like you can see on this image, where I've photographed a piece of paper and left it completely out of focus, so the only thing in the photo is the dead pixels.

It's annoying, but I still can use this particular camera, I just have to retouch the dots, but it could've been worse. I saw some people that had worse cases of dead pixels that made it not impossible but impractical to retouch every single photo due to the amount of damage to their sensors, which resulted in having to replace them. I the camera is used only for video, I don't think it's possible to remove them (depending on the amount of damage).

If you want to avoid this kind of problem, before setting your camera on a tripod to be stationary for the entire time (like me), be sure to check where the projectors are and where they are pointing.

Yeah, I remember reading Mykal Hall's experience of needing to replace his Olympus a few years ago after one of these lasers killed his sensor, too. It's good to see a reminder article such as this one sometimes, for those who haven't heard of the issue before.

The sad part of this story, is that a couple of days after my sensor was damaged by the lasers, I saw something about it (which would've helped me to prevent it from happen, a video or something like that talking about it). Lesson learned (the hard way)!

Sensors in general are more sensitive to excess light than the retina. Plus your eye only admits light going through the pupil which is 4-5 mm diameter at a light show, while a camera lens can gather most or all of the beam. (At longer distances, a light show beam can be wider than 4-5 mm so not all the light would go through the pupil.)

For this reason, the International Laser Display Association says laser show producers must make eye-safe shows but cannot be expected to be responsible for all the camera/lens/sensor combinations out there. More info is at -sensor-damage.htm

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