Do you have a stuck, dead, or hot pixel in a photo taken with your Canon? Of course you do — all sensors have defective pixels.
Different types of bad pixels
What are dead, cold, stuck, and hot pixels? A dead pixel is one that doesn’t receive any power; it will appear completely black. A cold pixel appears darker than the surrounding pixels. Stuck pixels always receive power and remain bright regardless of the shutter speed. Hot pixels increase in brightness with longer exposures.
At long shutter speed you will have faster dark current build-up in some pixels. This is what people often see when they take a dark frame with the lens cap on and what is commonly referred to as hot pixels.
Bill Claff at PhotonsToPhotos has a good description.
Methods to deal with bad pixels
Long Exposure Noise Reduction
Easy but slow. This feature is available in your camera’s menu. It removes defective pixels in both raw and JPEG images. You can choose between Off, Auto, and On. When the camera uses Long Exposure Noise Reduction, it takes a second shot called a dark frame. The shutter speed of the second frame will match the first one. So if your initial exposure is 1 minute, the dark frame will also take 1 minute. During this time, your camera will be locked and unavailable for shooting.
Increasing ISO
Some Canon camera models have a built-in hot pixel suppression feature. For example, the 6D, M5, and R6 remove hot pixels automatically at high ISOs (ISO 6400 for the 6D and M5, and ISO 12800 for the R6) without using dark frames. Any remaining hot pixels are typically the result of hot pixel pairs that Canon’s suppression system failed to fully remove. The 7D, however, does not have this feature.
6D sample raw files with sidecar files for darktable. Don’t use Lightroom, Adobe Camera Raw or other software that can’t turn off demosaicing or the hot pixel filter.
ISO 3200. Notice the pairs of hot pixels.ISO 6400. Almost all hot pixels gone. Left are pairs of hot pixels.
In camera sensor mapping
This method was the unofficial way to remove hot pixels before Canon confirmed it. If it works on your camera, it will remove defective pixels in raw, JPEG, and video. Just choose ”Clean now.”
A hot pixel visible until a ”Clean now” was performed via menu.
If you have an older DSLR and this method above doesn’t work, you can try the following workaround that people used before:
Keep the lens cap on and cover the viewfinder. Then, go to the menu and start manual sensor cleaning. Let it run for about one minute, then turn off the camera. If it doesn’t work the first time, repeat the process two or three more times.
The green, blue, and red pixels below were removed after a manual sensor cleaning. However, the single green pixel above the cluster remained, even after using the manual sensor cleaning method.
R50 and M200 have a different way to deal with hot pixels, see below:
How M200 works.
Raw converter
Easy and fast. This method relies on raw converters to remove defective pixels from raw files. Converters like darktable and RawTherapee offer a one-click module that removes all defective pixels in a single pass. Lightroom performs this correction automatically, but it doesn’t allow you to adjust the strength of the correction. Canon Digital Photo Professional does not remove hot pixels.
Below are two files you can try yourself. Note that Canon’s mRAW format is already demosaiced, so correcting it will be more difficult:
The GIF file below shows RawTherapee and what a hot pixel looks like before the raw file has been demosaiced. It also shows the hot pixel removal feature.
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