[FFmpeg-user] scaling algorithms

Michael Koch astroelectronic at t-online.de
Sat Oct 17 15:57:01 CEST 2015

 > That looks like the job for the filter, see inflate, deflate, erosion 
and dilation filters.

I just tested the dilation filter. It's a nice workaround if the 
downscaling factor is 3:1, as in my example. But if the downscaling 
factor is smaller, for example from 5472x3648 to 900x600, which is 6:1, 
then it fails. The star would be visible in 50% of the frames and 
invisible in the other 50%. What I need is a scaling algorithm which 
automatically chooses the brightest pixel out of the corresponding 
pixels from the input file. If the downscaling factor is 6:1, then the 
neighborhood is 6x6 pixels.


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