Patent ID: 7885470
Filing Date: 2011-02-08
Classification: G06T

Abstract:
1. A method for steganalysis of an image comprising: performing a JPEG decompression of an inputted JPEG representation of the image; reconstructing a spatial representation of the image from the JPEG decompression; performing entropy decoding of the JPEG representation, to obtain an entropy decoded JPEG representation; re-ordering the entropy decoded JPEG representation, to obtain a re-ordered entropy decoded JPEG representation; generating multiple non-overlapping, N×N block decompositions of the spatial representation of the image; applying block discrete cosine transform (BDCT) to each of the non-overlapping, N×N block decompositions to determine corresponding BDCT coefficient two-dimensional (2-D) arrays; forming one or more 8×8 JPEG coefficient arrays from the re-ordered entropy decoded JPEG representation; extracting moments using characteristic functions derived based on the spatial representation of the image the BDCT coefficient 2-D arrays, and the one or more 8×8 JPEG coefficient 2-D arrays, to obtain extracted moments; generating features based at least on the extracted moments, to obtain generated features; classifying the image based at least on the generated features; and determining a prediction error array for at least one of the spatial representation of the image, the BDCT coefficient 2-D arrays, or the JPEG coefficient 2-D arrays, wherein determining the prediction error array comprises computing a sign and a magnitude corresponding to a respective element of at least one of the spatial representation of the image, the BDCT coefficient 2-D arrays, or JPEG coefficient 2-D arrays, wherein computing a magnitude comprises computing an expression |a|+|b|−|c|, wherein a, b, and c correspond to elements neighboring the respective element; obtaining the sign of the at least one element; and computing the product of the sign and the expression to obtain a prediction corresponding to the respective element.