I am using this code to build an animated gif from a sequence of pngs: convert -dispose previous -resize 400x400 -delay 10 *.png -loop 0 -coalesce -layers Optimize output.gif.
it creates a gif with transparency, but when I overlay it over a jpg background, I get a weird result where a transparent box remains in the final image under my moving gif but over the jpg. From my tests, it seems this is a problem with the way I am building the original gif, but I have no idea. Also, I am stuck using GoDaddy's built in version of ImageMagick, which is 6.2.8 and sucks...all help and support seem to be for much newer versions. Does anyone have any ideas?
code to overlay: convert background.jpg overlay.gif -layers Optimize output.gif
which produces the following image:
The following works with GoDaddy's imagemagick 6.2.8
convert overlay.gif -coalesce -draw 'image Dst_Over 0,0 0,0 background.jpg' -layers Optimize output.gif
来源：https://stackoverflow.com/questions/34168718/imagemagick-gif-overlay-preserves-alpha-on-background