Stacking the same AVI multiple times

[mikehab]

Hi,

When processing a planetary AVI using something like AS!2 or Registax it always gives the option of choosing to do a quality sort and to take the 'best' # or best % of frames ... this got me thinking.

Say you have an AVI of 4000 frames and choose to take the best 10% (400) frames.  What would happen if you joined the same AVI back-to-back 10 times using something like VirtualDub to give an AVI of 40,000 frames - then take the best 10% of that.  Sure you would have the same 400 frames repeated 10 times - but would the result of stacking those 4000 good frames be better than just stacking the original 10% (400) frames?

Thanks,

Mike

[michael.h.f.wilkinson]

It would not improve matters. Stacking works because noise and distortion in frames are uncorrelated. If you duplicate frames, you create correlations (indeed, multiple frames are identical, yielding perfect correlation between them).

Uncorrelated noise adds up slower than the signal (adding 4 frames doubles the noise, but quadruples the signal, so the signal-to-noise ratio doubles). If noise is perfectly correlated, the noise adds up as fast as the signal, so there is no gain.

[Pete Presland]

No short cuts

Sent from my GT-I9100 using Tapatalk 2

[Laurie61]

What you can try is creating a better reference frame. Select a good single frame and then align with this, before stacking select the best 50 frames or so, stack these then use this as a reference frame and regrade using this. Then stack a larger appropriate number of frames and sharpen ect as normal to produce the final version.