Every digital camera sold on the market will have some hot or dead pixels. The sensor provided in commercially available camera’s will never be a 100% perfect and therefore wil contain hot or dead pixels. The only people receiving a 100% perfect sensors are organisations like NASA and they are paying millions of dollars for it. For the rest of us mortals, we have to resort to pixel mapping. I recently went through this process for my Leica M10.

What is pixel mapping

As camera sensors will have dead or hot pixels, manufacturers can include in the firmware of the camera functionality that compensates for these defective pixels. The camera uses the pixels surrounding the defective ones to compensate. This is a process called pixel mapping, where defective pixels are recognised and register the defective pixels.

Using camera firmware

Some camera’s have pixel mapping functionality as part of the standard firmware that comes with the camera straight out of factory. Fuji’s X-T4 and GX line of camera’s are an example of this. If you are detecting hot pixels or dead pixels, with these camera’s you can go into the menu settings and run the pixel mapping. It will detect any defective pixels and automatically map them to the surrounding pixels.

The Leica Q2 is another example of a camera that provides in-camera pixel mapping. The camera even runs the pixel mapping automatically every two weeks.

Pixel mapping for Leica M

The Leica M is one of these camera’s that do not provide in-camera pixel mapping. However, that does not mean that you cannot resolve this for you digital Leica M. I recently had an issue with my Leica M10, that required pixel mapping to resolve it. I will describe the process for this below.

When do you need pixel mapping

First of all, when do you know that you need pixel mapping? It all starts with the detection of some kind of anomaly that you detect in the images that you have been taking.

The first issue that you may detect are either small white spots in an otherwise dark image. This indicates that there are hot pixels. An example of this is presented below. 

You may also detect dark spots in image that do not seem to have information on it. This is an indication of dead pixels.

The last issue is the one that I had with my Leica M10. When I was shooting a backlit subject at a relatively high ISO rating (in my case ISO1600), a horizontal line appeared across the full image. It was not consistent, but in certain situations this would appear. An example of this is presented below. In the crop, the line has been marked by the ellipse.

Process with Leica

Obviously, I needed to resolve this issue ASAP. So, I contacted my local Leica store and explained the issue. They said it can be resolved with an update of the firmware that is specific to your camera. You need to provide a number of images that show the issue (I provided 6 images), as well as the serial number and firmware version of your camera (mine was version 3.22.23.38).

Leica Wetzlar then creates a custom version of firmware specifically for your camera that maps the defective pixel. The version number of the firmware you will receive is the same version as you are running. You need to format an SD card with your camera and store the firmware on it. Then go in the menu and update the firmware as normal. It was really quick, so it is not a large firmware update. According to Leica, when new firmware is available for your camera, you can update as normal. The pixel mapping will be permanent.

All this was provided to me free of charge, so kudos to Leica. Of course, it would be even nicer when pixel mapping was part of the standard firmware of the digital Leica M, but in the end all that counts is that they resolve the issue. Turnaround was really quick: I sent in my images to Leica and a few hours later the firmware was available.