Bitmap Scaling Algs

[GRIFFIN,JEFFREY A]

Does anyone have an algorithm for scaling bitmaps?  I am looking for something
that will scale to a given size, X by Y.  Does anyone have an algorithm that
would scale a bitmap by superimposing a fixed size grid over the bitmap and 
determine the values for each box of the grid.  The subs can be in Fortran or
C.  Any suggestions or better ideas would be much appreciated.  Thanks for the
help!!