There are two things about this that can be improved, first the noise can be reduced, and second the picture could be brighter.
This is similar to the noise reduction process but this time because the pictures are darker than normal there is no need to find an average, the sum must be adjusted to have the correct brightness range. This is achieved by using the DFT routines, setting the input to the whole stack, a filter that does nothing, and brightening the output.
Here is a slow movie, 1 second per frame, of ten frames taken
down the microscope, it shows dust accumulated on the stage after standing for
some time without a dust cover, the light comes from above and is not strong
enough.
There are two things about this that can be improved, first the noise can be
reduced, and second the picture could be brighter.
Here is a single frame made brighter, you can see how the noise
is amplified.
And here are all 10 frames added together and the brightness
adjusted
Here is the procedure
1. Start CombineZM do not define any DFT filters.
2. Load the frames to add.
3. Click on Filter Menu->Input->Sum of Stack, the frames will be added together, but the result will still appear dark.
4. Click on Filter Menu->Output->Brighten and use the usual arrow keys, M or N or V to alter the brightness.
If you include even more frames you will get an even clearer result. Astronomers use this technique to clean and improve their pictures.