rotate

Name

rotate - rotate transform

Syntax

 #include <xite/geometry.h>

 int rotate( IBAND inband, IBAND outband,
    double theta, double rx, double ry, int ip,
    int bg );

Description

The input band is rotated around the point (rx, ry) in the global coordinate system. Thus, a band of size 25x25 with xstart=ystart=100 should have rx=ry=112 to be rotated around its center. If xstart=ystart=1, global coordinates equal local coordinates.

theta is in radians.

 outband (x,y) = inband (u,v)
 u = cos(theta) *  x - sin(theta) *  y
   - cos(theta) * rx + sin(theta) * ry + rx
 v = sin(theta) *  x + cos(theta) *  y
   - sin(theta) * rx - cos(theta) * ry + ry

The interpolation method ip is one of

0

Nearest neighbor

1

Bilinear interpolation

      g(x) = bi(f(x), f(x+1), d)
      bi(x, y, d) = x(1-d) + yd

3

Cubic interpolation

      g(x) = cc(f(x-1), f(x), f(x+1), f(x+2), d)
      cc(x, y, z, v, d) = y + d((-x+z) +
             d((2x-2y+z-v) + d(-x+y-z+v)))

bg specifies the background pixel value.

Restrictions

inband and outband must have pixel type unsigned byte.

Return value

 0 : Ok
 1 : Bad input or output pixel type

Reference

Wayne Niblack. Digital Image Processing, p 131-150

Author

Otto Milvang

Id

$Id: rotate.c,v 1.30 1997/06/03 13:49:51 svein Exp $