Frame Summing vs. Frame Averaging

[Brian Przypek]

Can anyone offer a detailed description on the advantages/disadvantages of frame summing and averaging?

I do a lot of long exposure time-lapse with DSLR's and would like to use my Epic to similar effect.

Example footage/frame grabs would be much appreciated to highlight the difference between the two processes.

 

[Michael Notar]

i share your question as i asked it but have not heard back from others.

 

[Terry VerHaar]

Start with RTM... p. 131-132.

 

[Andrew Gentle]

My understanding is that frame summing and frame averaging do exactly what they say.
Each pixel value in frame summing is added up to produce an image. In frame averaging, the same happens, but the value is divided by the number of frames before it's stored. So, if you have an underexposed base image, frame summing will make it n stops brighter for n summed frames. Frame averaging means you won't have an exposure change. I presume frame summing would also raises the noise floor by n stops?

 

[Trent Lillehaugen]

My understanding is that frame summing and frame averaging do exactly what they say.
Each pixel value in frame summing is added up to produce an image. In frame averaging, the same happens, but the value is divided by the number of frames before it's stored. So, if you have an underexposed base image, frame summing will make it n stops brighter for n summed frames. Frame averaging means you won't have an exposure change. I presume frame summing would also raises the noise floor by n stops?

A couple of notes:

- A stop is twice as much light, so summing 4 frames will change the exposure by 2 stops (not 4). For N frames the change in exposure will be: log N / log 2
- The summing and averaging are performed in camera before encoding.
- Each individual frame will have the selected exposure time (or angle). This means there can be some interesting motion artifacts (especially if the shutter angle is not 360)

 

[Fernando Tufiño]

There should be a Red instructional video por this function, I still can understand the concept without seeing it