Hot Pixels

[gr2k]

i'd just like to share some info here..might be helpful to some :)

let's just start with saying a 'Hot Pixel' isn't a defect...hot pixels are something like 'dead pixels on your picture'...any camera has a chance of getting them..

*Hot pixels appear on your image, dead pixels apper on your LCD*


Hot pixels:
1. Come and go (or sometimes stay, unfortunately)
2. Usually appear at the same spot
3. Can be easily removed with a clone/healing tool in PP (altho extremely annoying)
4. Have a chance of occuring in any brand new/used/old cameras (depends on your luck)


Hot pixels appear as unusually bright pixels on your picture...here's an example of a hot pixel (the green 'stars'):

26908
"Hot pixels are also available in red! :P"

How to get around it:
1. Hot pixels are more prominent at high ISOs..so keep it down
2. Higher magnification = more visible hot pixels
3. Hot pixels have a higher tendancy to show in hotter temperatures. So...shoot in cold temps? lol
4. Hot pixels are more visible in long exposures (although they do appear in exposures as fast as 1/8000, too)

Get it out!!!!:
1. Unfortunately, you can't
2. Since hot pixels appear in the same spot, at least you'll know where to find them to clone/heal the spot in PP
3. It comes and goes..changing the sensor/buying a new camera doesn't mean you won't get it again..don't waste your money
4. You could do some NR but this kinda makes it become a smudged bright pixel. At the same time too much NR reduces the sharpness on your image.

i'd like to say it's not very noticable...unfortunately sometimes it is..i mean what do you expect? it's an oddly bright pixel on your image!

especially when your image just happens to have a dark region where the hot pixel is, then it becomes even more prominent..

ultimate solution? a Spot Healing Brush in photoshop will fix it up nicely.

[kiankheong]

g2rk, yeah hot pixels and dead pixels give the same effect, but they are totally different. You get weird colours due to Bayer interpolation.

Hot pixels are randomly located, dead pixels are permanently located.

Usually dSLRs have dark frame subtraction to counter hot pixels. The usual way is still to use the healing brush during post-processing.

For laboratory settings, some cool their CCDs using Peltier devices. Extreme conditions even demand liquid nitrogen cooling.

Some people even mentioned that hot pixels are more common after continuous usage of camera in a single session.

[noruazumi]

I've set my camera to f/2.8, ISO3200 and 30 seconds shutter speed.
And I got blue, green & red dots. :run_away:

[gr2k]

i don't recall the weird colours being due to Bayer interpolation. Although on some cameras hot pixels are seen as one pixel. The image in the first post shows the hot pixels in a sort of 'star-shape'. Now that is due to Bayer interpolation

Hot pixels are not randomly located...they randomly appear at the same spot. (you can always get more than 1 hot pixel which is why some ppl think it's randomly located) :)

now why sensors pick up hot pixels is basically because of electric charge leakage on that particular pixel which increases the voltage (for that particular pixel) resulting in an 'over-bright' pixel...this leads to relation of extensive usage:

Extensive use of a camera means the CCD/CMOS is constantly being charged-up, which likely causes heat build-up, hence the Hot pixel.



I've set my camera to f/2.8, ISO3200 and 30 seconds shutter speed.
And I got blue, green & red dots. :run_away:
haha your camera is suffering from hotness! :D

[kiankheong]

Just to share my experience with dead pixels on my former Coolpix 5700.

There were two stuck pixels, and they were always there, no matter what time of shooting or settings.

There's a Russian software to remap the CCD pixels, as not to utilise information collected by the stuck pixels. It works, but your warranty may be void.

I have sent to Nikon for remapping too. But it took me 1-2 weeks to get back my camera.

Oh, you are right. Bayer interpolation artefact is seen in dead pixels, not really on hot pixels.

Perhaps in your particular CCD, that particular pixel is prone to being hot pixel, giving it an apparent permanent location. Certainly plausible.

[gr2k]

yea i've heard of the software to remap too..asked nikon: warranty will be void :run_away:

[dinduboy14]

INteresting! Thanks for sharing :thumbs_up: