Forensics of High Quality and Nearly Identical JPEG Image Recompression

We address the known problem of detecting a previous compression in JPEG images, focusing on the challenging case of high and very high quality factors (≥90) as well as repeated compression with identical or nearly identical quality factors. We first revisit the approaches based on Benford- Fourier analysis in the DCT domain and block convergence analysis in the spatial domain. Both were originally conceived for specific scenarios. Leveraging decision tree theory, we design a combined approach complementing the discriminatory capabilities. We obtain a set of novel detectors targeted to high quality grayscale JPEG images.