1. An image processing apparatus comprising a computer for detecting a contour of an object from an image including a shot of the object, said apparatus comprising: an image input processing portion that inputs the image; a feature point detection processing portion that detects a plurality of feature points of the object from the input image; a posture estimation processing portion that estimates a rotation angle indicating a posture of the object from the plurality of detected feature points; an initial parameter estimation processing portion configured to estimate initial parameters in order to detect the contour of the object from the plurality of detected feature points; an initial parameter correction processing portion that corrects the estimated initial parameters using the estimated rotation angle; and a contour generation processing portion that generates the contour of the object using the corrected initial parameters, wherein the initial parameter estimation processing portion estimates reference points for the detection of the contour from the plurality of detected feature points, such that the estimated reference points are used as the initial parameters, the initial parameter correction processing portion computes a normalized contour vector, which is normalized by multiplying each component of a sample principal vector showing a contour of a pre-stored object with a coefficient, and the initial parameter correction processing portion computes corrected reference points and a corrected, normalized contour vector by correcting the computed normalized contour vector and the estimated reference points based on the estimated rotation angle of the object, such that the corrected reference points and the corrected, normalized contour vector are used as the corrected initial parameters.