Mondrian painting description language
Perl 5 + ImageMagick - 297

Something to start with:

sub a{my($x,$y,$X,$Y,$d)=@_;$_=shift@ARGV;
/v/?a($d=$x+($X-$x)*$'/100,$y,$X,$Y).a($x,$y,$d,$Y):
/h/?a($x,$d=$y+($Y-$y)*$'/100,$X,$Y).a($x,$y,$X,$d):
/c/&amp;&amp;"-fill ".qw/white red blue yellow/[$'-1]." -draw 'rectangle $x,$y $X,$Y' "}
system"convert -size 256x256 -stroke black xc: ".a(0,0,255,255)."a.gif"


Takes input on command line and generates a.gif.