ImageMagick Compositing only works with transparent PNGs
tl;dr if the PNGs are not transparent then you can’t overlay / composite!
Pontifications
- Generate Transparent GIF files in R using
bg = "transparent": (I learned this from a stack overflow question on ggplot2 transparency; official png() docs)
png(file=filename, width=1024, height=1024, res=72, bg = "transparent") - Then everything works:
convert 0000001-first360-flickr-roland-2004-12-avgcolour.png 0000002-first360-flickr-roland-2004-12-avgcolour.png\
-composite 1-2.png
convert 1-2.png 0000003-first360-flickr-roland-2004-12-avgcolour.png\
-composite 1-2-3.png
convert 1-2-3.png 0000004-first360-flickr-roland-2004-12-avgcolour.png\
-composite 1-2-3-4.png
convert 1-2-3-4.png 0000005-first360-flickr-roland-2004-12-avgcolour.png\
-composite 1-2-3-4-5.png