METHOD AND APPARATUS FOR INSERTING AND DETECTING WATERMARKS IN IMAGES DERIVED FROM SOURCE IMAGE

摘要

PURPOSE: A method and apparatus for inserting and detecting watermarks is provided to insert watermarks in a digital image restricted by a bounding rectangle. CONSTITUTION: In a method and apparatus for inserting and detecting watermarks in images derived from a source image, a bounding rectangle has dimensions with a width of N pixel and a height of N pixel. If the source image is greater than the bounding rectangle in horizontal and/or vertical dimensions, its horizontal and vertical dimensions are shortened by horizontal and vertical factors or a common factor until the source image is perfectly in the bounding rectangle and its parallel edges adjoin parallel edges of the bounding rectangle. If the source image is smaller than the bounding rectangle in horizontal and vertical dimensions, its horizontal and vertical dimensions are enlarged by the common factor until its parallel edges adjoin parallel edges of the bounding rectangle. The shortened source image, the enlarged source image or a source image not required of size adjustment is called "adjusted image". The watermarked image derived from the adjusted image is enlarged or shortened to adjoin at least a pair of parallel edges of the bounding rectangle, so that the image is perfectly in the bounding rectangle, thereby easily detecting embedded watermarks.