There are provided an image processing apparatus, an image processing method and an image processing program for transforming a target image having no contour of straight line portions.
An ellipse El by which the target image is approximated is calculated (S20), a center candidate O A of the target image is decided (S21), a first polygon P1 associated with the ellipse and the center candidate is calculated (S22), a projective transformation matrix for projectively transforming the first polygon into a second polygon P1' associated with an ellipse whose center is a point where the center candidate is projectively transformed is calculated (S23), and the target image is projectively transformed based on the projective transformation matrix to obtain a transformation image (S24).