  In the case that images are shared via social networking services (SNS) and
cloud photo sharing services (CPSS), it is known that the JPEG images uploaded
to the services are often re-compressed and resized by the providers. Because
of such a situation, a new image identification scheme for double-compressed
JPEG images having different sizes from that of a singled-compressed one is
proposed in this paper. The aim is to detect a single-compressed image that has
the same original image as the double-compressed ones, even when the sizes of
those compressed images are different. In the proposed scheme, a feature
extracted from only DC coefficients in DCT coefficients is used for the
identification. The use of the feature allows us not only to robustly avoid
errors caused by double-compression but also to perform the identification for
different size images. The simulation results demonstrate the effectiveness of
the proposed one in terms of the querying performance.
