[FFmpeg-user] How to make partially transparent png image

[compname at verizon.net]

At 6/28/2015 02:09 AM, you wrote:

> > Since ffmpeg is a video processing tool, even if it could I wouldn't
>recommend it.  I used another free tool: IrfanView.  I believe you can load
>an image into it & tell it to make a certain color/range of colors
>transparent.
>
>IrfanView is not free

Well, OK for commercial use it's not free.  But just about any 
business (that's planning on staying in business anyway) isn't going 
to quibble over the $12 reg. fee.  And for us 
individuals/educators/etc. it is free.

>  and ffmpeg have already tools to make certain
>color/range of colors transparent.

I've recently used the geq filter to do just that.  But I never 
considered FFmpeg to be a (still) image editor/converter, even though 
it does work nicely as such (-i in.bmp -vf [image filters] -c:v png out.png).