  This paper focuses on the JPEG noises, which include the quantization noise
and the rounding noise, during a JPEG compression cycle. The JPEG noises in the
first compression cycle have been well studied; however, so far less attention
has been paid on the JPEG noises in higher compression cycles. In this work, we
present a statistical analysis on JPEG noises beyond the first compression
cycle. To our knowledge, this is the first work on this topic. We find that the
noise distributions in higher compression cycles are different from those in
the first compression cycle, and they are dependent on the quantization
parameters used between two successive cycles. To demonstrate the benefits from
the statistical analysis, we provide two applications that can employ the
derived noise distributions to uncover JPEG compression history with
state-of-the-art performance.
