Exposing Blur Kernel from Retouch Image

The blurring in image comes either from the acquisition noise, or from image editing operation. The produced adverse noise during acquisition need to be eliminated, and the blurring generated by editing should be known in digital forensics, so the blur kernel recovery is significant in community of image processing and computer graphics. In the log-fourier domain, the images before and after blurring bears the isometry, therein an approach of gaussian blur kernel recovery based on Riemannian geodesic is proposed, which evaluates the blurring-invariant quantity between the original image and blurred one, and recovers the blur kernel from blur image. The presented method is testified in images convolved by gaussian blur, median blur, box blur and multiple gaussian blur, and the kernel could be robustly recovered from gaussian blur image. Moreover, the discussed method is capable of authenticating the retouch image generated from blurring.