I wondered why, when taking long exposures, the camera would take 2x as long to load the image onto the SD card when someone explained that the camera (Olympus OMD EM-5, original version) takes a second exposure with the shutter closed (a “black” image) to reduce the noise created by long exposures.
There also was a suggestion that I could disable that option (save battery life) and do something similar to the “black” image in post.
Using either (or both) darktable and gimp, how would I accomplish this?
You’d still need to shoot a black frame at the time you did the image exposure, but you could then use it in post for all the images from that scene.
This is bread-and-butter for astro photographers; they’ll shoot multiple dark frames, as the statistical median of all those makes for a better noise subtractor than a single dark frame.
Astrophotographers tend to take a number of dark frames and use them to create a “master dark frame” using median blending in general. Since it takes a lot of time to collect all those individual dark frames (they often use 20-50 individual frames), if their shooting conditions don’t change significantly (exposure parameters + ambient air temperature) they keep using the same set of dark frames or master dark frame for something like 1 year.