2

I found this strange little cross on pictures when I was doing some long exposure photography. I have had some experience with hot pixel in the past, but this thing seems completely new to me.

(1:1)

(1:1)

I'm talking about the little white cross on the picture. It acts totally like a hot pixel, but its form is quite interesting. I have got several of these across my photos/sensor, some brighter than the other.

I'm using the Canon EOS 600D (Rebel T3i in the USA). I have tried the hot pixel fix you can find on the internet on this, but the crosses won't disappear (but that doesn't mean everything, because there are more hot pixels that don't disappear).

Is this a hot pixel? And how do I fix it?

2

That is what a hot or stuck pixel looks like when it is so "hot" that the fully saturated signal from one pixel figures prominently into the interpolated values of surrounding pixels when the data from the sensor is demosaiced to create colors from the monochromatic luminance values captured by each pixel well on the sensor.

If it is a hot pixel the way to fix it is to allow the sensor to cool down before taking any more photos. If it is a stuck pixel (which stays on every time the camera is used, even when cool) the way to fix it is to either replace the sensor or have the manufacturer map that pixel out of the sensor's readout. Canon will do this (but the fee is several hundred dollars) for any stuck pixels on a sensor, at least among their mid/pro grade bodies. Some, but certainly not all, other manufacturers offer similar pixel mapping.

  • Be aware that while the temperature-based distinction you are making between "hot" and "stuck" is one way of using the terms, another (and, I think perhaps older, for better or worse) definition uses "hot pixel" to mean that a triad of red/green/blue pixels in an LCD screen are all stuck on, resulting in a white dot (with no regard for temperature). – mattdm Apr 30 '14 at 0:34
  • I've always heard the monitor pixel that was always on referred to as a stuck pixel. – Michael C Apr 30 '14 at 2:33
  • One subpixel is "stuck"; three together is "hot". I like the temperature distinction better, but unfortunately I am not making this up, so there's plenty of room for confusion. – mattdm Apr 30 '14 at 2:39
  • In the context of a camera sensor they are all monochromatic. There is no RGB trio that makes a single pixel, unless your camera has a rare foveon type sensor. – Michael C Apr 30 '14 at 3:07

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.