Patent ID: 8452110

Claim:
A program storage device readable by machine, tangibly embodying a program of instructions executable by the machine to perform a method of classifying a compressed input image's compression level, comprising: applying inverse quantization to discrete cosine transform (DCT) coefficients extracted from the compressed input image giving rise to dequantized DCT coefficients; identifying a lowest absolute non-zero DCT coefficient among said dequantized DCT coefficients; applying a threshold to said dequantized DCT coefficients, wherein said applying a threshold includes applying a threshold to said lowest absolute non-zero DCT coefficient; and determining a compression level classification for said compressed input image according to a relation among said threshold and at least one of said dequantized DCT coefficients, wherein said determining a compression level classification, comprises determining a compression level classification for said compressed image according to a relation among said threshold and said lowest absolute non-zero DCT coefficient.