Optimum anamorphic image generation using image rotation and relative entropy

Abstract

Anamorphosis is related to the art that gives illusion (distortion) over the image or object when the viewer looks the original image or from the random viewpoint. This illusion effect is nullified when the image or object is viewed from the standard viewpoint. In digital imaging domain, anamorphic images (distortion) are generated by changing the pixel coordinates of the given image into new pixel coordinates, and this process typically increases the size of the original image matrix which results in gaps between the successive pixels. In anamorphic transform, the gaps between the successive pixel positions increases as we travel from viewing end to the tail end, and these gaps are filled by interpolating the successive pixels. The viewing angle, distance, height between the viewer and original image are responsible for the amount of distortion introduced in anamorphic images. The proposed work reveals that the rotation of the original image also plays an important role in creating distortion in anamorphic images. The proposed work uses the Kullback-Leibler distance (KLD) to measure the amount of distortion between the original and anamorphized images. A larger KLD implies that the original and anamorphic images are well separated i.e., a good anamorphism has achieved. It is found that the smaller viewing angle combined with the viewing distance and height achieves the larger KLD. The optimum anamorphic image generation is done at two levels: (i) Choosing an appropriate viewing angle, distance, and height, and (ii) Choosing the appropriate rotation of the image to be anamorphized. The former is optimized through KLD, and for the latter Shannon’s entropy of the tail portion of the original image under different rotations is used. The proposed technique is tested on various images with different resolutions and is found to be working properly.