Rotating hue animation:
<code=bash>
STEP=20
DELAY=15
echo Hue-shifting images in parallel...
for R in `seq -w 0 $STEP 200` ; do
  (convert $1 -modulate 100,100,$R TEMP_$R.png ; echo Shift $R done) &
done
echo Waiting for jobs to finish...
wait
echo Jobs done, rendering animation...
convert -delay $DELAY -loop 0 TEMP_*.png $2
rm TEMP_*.png
</code>

"Yospize": Bright green edges on dark green fill
  convert in.gif -despeckle -edge 2 -channel G -function Polynomial 1,0   -channel RB -function Polynomial 0 fg.gif
  convert in.gif -colorspace gray   -channel G -function Polynomial 0.2,0 -channel RB -function Polynomial 0 bg.gif
  convert fg.gif null: bg.gif -compose lighten -layers Composite out.gif

Greenify mode (light-on-dark stuff)
  convert in.gif -colorspace gray   -channel G -function Polynomial 1,0 -channel RB -function Polynomial 0 out.gif

Inverse greenify mode (dark-on-light stuff)
  convert in.gif -colorspace gray   -channel G -function Polynomial 1,0 -channel RB -function Polynomial 0 out.gif