[FFmpeg-user] scaling algorithms

Paul B Mahol onemda at gmail.com
Mon Sep 20 22:51:27 EEST 2021


On Sat, Oct 17, 2015 at 3:58 PM Michael Koch <astroelectronic at t-online.de>
wrote:

>  > 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.
>

See  new morpho filter, that gonna be in master soon.

It is much faster than current filters and allow custom definition of
structure/mask (rectangle/circle/etc) by using 2nd stream.


>
> Michael
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