Re: [CinePaint] Looking for a feature useful to smooth timelapse sequences - grading

On Wed, 22 Nov 2006 07:41:40 -0800
"John Arrowwood" <[email protected]> wrote:

> I once wrote a script that took a timelapse sequence and calculated
> the 'average' of some number of frames before and after each frame.
> So I took the 15 frames before and the 15 frames after, or about one
> second of video time, and took all 31 images and produced an 'average'
> image.  I then used that as the frame for that moment.  Naturally, I
> did the same thing with every single frame.  The end result was
> amazingly smooth.  It was exactly what I wanted, as far as light
> conditions goes.  The flashes of light were completely gone.  But cars
> in motion were completely removed from the image, too!  The lighting
> was perfect, but the action was missing!
> 
> What I need is to automate the task of taking the actual frame and
> tweaking it so that its overall appearence most closely matches that
> average image.  It's just math, right?  It has to be possible!  If I
> can find a way, then the end result would be as smooth as the average
> image as far as overall lighting goes, but with all the details of the
> individual frames intact.
> 

What exactly is this "average" image?  Upon what basis are you
computing this "average?"

Most likely you need to adjust the histogram of the image
to correct for any deviation in exposure between adjacent
frames.  Cinepaint now includes the script-fu module to 
automate image processing.  You can also consider the NETPBM
suite (http://netpbm.sourceforge.net).  In particular,
a utility called "pnmnorm" allows for an automated histogram
normalization.  Also, the ImageMagick suite (www.imagemagick.com)
allows for automation in adjusting histograms.

Frank Peters


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