%o = option
%f = filename
%g = geometry

function %o %g %f %f-.jpg

FUNCTION
convert	(create new image)
mogrify	(modify image)
identify	(read image metadata)

OPTION and GEOMETRY
NOTE: Options can be run multiple times in a single command.
+append %f %f2 %fout.ext	(append right)
-append %f %f2 %fout.ext	(append down)
-colorspace gray
-crop
-fill	(choose fill color)
-flip	(mirror ^v)
-flop	(mirror <>)
-monochrome	(black and white, no grayscale)
-resize 
-rotate (clockwise;fills non-90 multiple with whitespace)
-trim	(remove excess border space such as whitespace)

GEOMETRY
50%x	50% the width
50%x20%	50% of the width and 20% of the height
x20%	20% of the height
-10-20	10 pixels from the right, 20 from the bottom
+10+20	10 pixels from the left, 20 from the top

EXAMPLE
convert -crop +10+10 -crop -10-10 -trim	(remove 10 pixels from each side and trim the result)
identify -verbose %f|grep comment|less	(read comments in less)