2Dwave/image interpolation

Hello,
I have a 2D wave of which I have created a plot as shown here:
http://www.igorexchange.com/node/3515
Now, I would like to interpolate my 2d wave (even if only on the X axis) because of the few points on X axis.
How I can do this?
thanks, I am attaching the file with the 2d wave and the two waves to the X and Y axis edges
interpolation.pxp