getWidth and Height for preparing the grid

[jarek-6]

hello once again,

one more question about macros:
i know how to getWidth and Height of the image, what i want to do now is
to superimpose a grid where "Area per point " will be equal a*b, where a
= width/2; b = height/3.
i work with imagej with plugins bundled by wcif. grid command is:

run("Grid ", "grid=Lines area=19.09 line=1");

thanks in advance,

jarek