DEMYSTIFYING HISTOGRAMS OF MULTI-QUANTISED DCT COEFFICIENTS
Thomas GloeAbstract
JPEG compression artefacts are among the most prominent features in the forensic analysis of digital images. Here, we focus on the spectral analysis of histograms of single- and multi-quantised DCT coefficients. We present a model of the frequency response of finite-support histograms, which explains position and magnitude of characteristic quantisation peaks with reasonable precision and gives valuable insights into the formation of quantisation artefacts in general. We derive a set of practical rules for the efficient analysis of single- and multi-compressed images and discuss applications in the estimation of quantisation tables.
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