The invention discloses a method for the automatic extraction of the position of a 
license plate in a vehicle monitoring image and perspective correction, and the method comprises the steps: finding an approximate range of the 
license plate in the image through employing the edge and color information; carrying out the linear detection of the image; determining four boundary lines forming a perspective deformation 
license plate through employing the regional boundary information and combining with significant straight lines; solving four intersection points of the significant straight lines, and building mapping relation between the four intersection points with four corners of a target rectangle; carrying out the reverse calculation of a perspective correction matrix, and completing the perspective correction of a license plate. The method obtains the positions of four corners of a license plate with 
perspective distortion, builds the mapping relation between the four corners of the license plate with 
perspective distortion and the four corners of the target rectangle, calculates a 
perspective transformation matrix, and completes the perspective correction of the license plate. Compared with an affine transformation method based on 
horizontal and vertical rotation, the method truly describes the 
perspective transformation, and guarantees the higher license plate 
image correction precision. Compared with an affine 
transformation algorithm, the method can detect the 
perspective distortion information of the license plate, also can precisely locate the boundary corners of the license plate, calculates the 
perspective transformation matrix, and accurately achieves the perspective correction of the license plate.