# macro for bilinear interpolation - Written by Dietmar Kunz
loop
{   x0=x-( x & 3); 
    y0=y-( y & 3 );
    if(x<( XSIZE-4 ) && y < ( YSIZE-4) )
    {    dx = x-x0;
         dy = y-y0;
         i = (image[1][0][x0][y0] * (4-dx) * ( 4-dy) + image[1][0][x0+4][y0] * dx * (4-dy)
            + image[1][0][x0][y0+4] *(4-dx)*dy + image[1][0][x0+4][y0+4]*dx*dy)/16;
     }
}