1. An image processing apparatus for processing images picked up by a camera to detect objects in the images, comprising: a memory for storing image data corresponding to the images picked up by the camera; an image processor for processing said image data stored in said memory and detecting an object in said processed image data; and a display for displaying processed image data including the detected object output by said image processor, wherein said image processor transforms an image on a first coordinate system representing a coordinate system during pickup to an image on a second coordinate system set up on a plane representing a reference, displays the transformed image on said display, receives setting information input by a user in accordance with a display of the image by said display, and transforms the picked-up image or/and parameters necessary for detection by using the received setting information and then detecting an object from the picked up image by using the parameters.