Extending work of Hochman, we study the almost-Borel structure, i.e., the non-atomic invariant probability measures, of symbolic systems and surface diffeomor-phisms. We first classify Markov shifts and characterize them as strictly universal with respect to a natural family of classes of Borel systems. We then study their continuous factors showing that a… (More)
Noise is an important factor in image quality. We analyze it in images produced by digital cameras. We show that, beyond the usual standard deviation measurement, spatial correlations also convey interesting information which allows to (i) better describe the perception of the noise, (ii) analyze an unknown imaging chain. Indeed, knowledge of these spatial… (More)
We propose and evaluate a method to determine whether a given digital image is the result of a digital zoom in or more generally of a linear interpolation. This information is important to some post-processing. It also sheds some light on the actual resolution of some digital cameras.