An image processing apparatus, comprising:
- reduction calculation means for reducing the number of a plurality of input image data, corresponding to a plurality of images that satisfy azimuth difference relations each other, in a lateral direction, respectively;
- three-dimensional processing means for combining the image data that have been reduced the number by the reduction calculation means so as to prepare a three-dimensional image data;
- and
- switching means for switching and selecting which one of three-dimensional image data prepared by the three-dimensional processing means and two-dimensional image data prepared by using one of the plurality of input image data should be outputted.