1. An image processing apparatus comprising: an image-conversion-parameter storage unit having stored therein in advance, as image conversion parameters to coordinate-convert images of in-vehicle cameras incorporated in an own vehicle, a plurality of directions connecting between a sight-line starting position of a driver and a plurality of predetermined positions of the own vehicle, values of a depression angle from the sight-line starting position of the driver, and a range that the driver is caused to visualize corresponding to a positioned state of the own vehicle, for each of the in-vehicle cameras incorporated at different positions of the own vehicle; a state determining unit that determines a current state of the own vehicle; an image converting unit that coordinate-converts an image captured by each in-vehicle camera, based on a result of a state determined by the state determining unit and the image conversion parameters stored in the image-conversion-parameter storage unit; and a display and output unit that outputs and displays an image converted by the image converting unit.