This paper proposes Topview Transform Model approach of the image coordinate transformation, which is to transform perspective projection image into its corresponding bird's eye version. A heuristic searching algorithm estimates the parameter values used to perform the transformation from the source image. Using this approach, it is not necessary to provide an exact intrinsic or extrinsic camera or installation parameters. The designed car parking assistant system can be installed at the rear end of the car, providing the driver with a clearer image of the area behind the car. The processing time can be reduced by storing and using the transformation matrix estimated from the first image frame for a sequence of video images. The transformation matrix can be stored as the Matrix Mapping Table, and loaded into the DSP platform to perform the transformation. Experimental results show that the proposed approaches can provide a clearer and more accurate bird's eye view to the driver of the car.