imagemagick - animate, with a static black background? - imagemagick

Question

Just a quickie.
I have a series of images min*.png that I want to animate into a gif.
They are each fully transparent, except for some white dots on the area I want filled in for that frame.
Is there some way to create an animation from these such that the background is black (so that the whtie dots show up?)
I am interested in both:
black background, and paste each successive image on top of the previous ones (so frame i is the black background plus all of the dots up to image i)
each frame consists of just (image i on a black background)
I think for 1. I need to use -dispose none and for 2 I use -dispose background or -dispose previous, but various attempts at actually setting the background to black have failed (I have spent a lot of time reading this imagemagick page but am still learning).
e.g.
convert -background black -dispose background min*.png out.gif
various attempts with -background and -dispose have invariably produced a gif of my min*.png with a transparent background, not a black one. I think I'm close, but not sure.

Answer 1

This may be useful for the black background problem: starting from ImageMagick 6.7.5 you can remove transparency and replace it with a static color; you can read more about this command here
Hope this helps, unfortunately I have an older version of Imagemagick, so i can't try it myself
Example from ImageMagick documentation:
convert moon.png -background tan -alpha remove alpha_remove.png
The color "tan" replaces the transparent areas of the picture
Comment from mathematical.coffee
Using the above answer, I was able to generate the animations I wanted.
1: successive buildup of dots, all on a black background. Turned out to be as simple as creating a black background picture to put at the start of the animation, and using -coalesce:
# where bg.png is a black png of the appropriate size:
convert bg.png min*.png -coalesce out.gif
# in the below the first line creates the black background
# image, same size as my first min00.png image, for me:
convert min00.png -alpha Opaque +level-colors black \
min*.png -coalesce out.gif
2. use the method mentioned above:
convert min000*.png -background black -alpha remove out.gif
In both I was using imagemagick 6.7.something.