ffmpeg and imagemagick

-pattern_type glob -i 'raw/*.png'  # repeat this to combine more than one pattern
-loop -1  # for GIFs; number of times a gif plays; -1==infinite
-r 1.5  # framerate
-framerate 1.5  # same as -r

ffmpeg -r 1.0 -i 'prefix_%04d.png' raw.gif
ffmpeg -r 1.0 -pattern_type glob -i '*.png' raw.gif
# problem: all images will be resized to the size of the first one (distortion)
# solution: use imagemagick
# problem2: low quality.
# solution2: use palette (see below)

ffmpeg -r 0.5 -pattern_type glob -i '*.png' -c:v libx264 -pix_fmt yuv420p out.mp4
# problem: all images will be resized to the size of the first one (distortion)
# solution: use imagemagick

ffmpeg -i prefix_%02d.png -vf "palettegen" palette.png
ffmpeg -i prefix_%02d.png -i palette.png -filter_complex "paletteuse" output.gif

-delay 100  # hundreds of a sec
-loop 5
-dispose previous  # remove previous frame in the animation
-gravity center  # center images
-thumbnail 000x000  # resize image
-extent 000x000  # adjust the image in a frame of this size

mogrify -geometry 640x480^ -gravity center -crop 640x480+0+0 *.png
# force all images do to be 640x480. If bigger, cropped from the center

mogrify -thumbnail 640x480 -background black -gravity center -extent 640x480 *.png
# pad with black background

convert -delay 200 -loop 5 -dispose previous *.png -gravity center iamanimating.gif
# also creates a gif animation