Abstract: A controller for controlling a signal processor includes a transformation unit and a control unit. The transformation unit is configured to generate at least one amplitude-modulation-to-phase-modulation-distortion within a signal, output by using the signal processor according to a signal processing, based on generated at least one amplitude-modulation-to-amplitude-modulation-distortion of the signal. The control unit is configured to adjust the signal processing of the signal processor so as to minimize the at least one amplitude-modulation-to-phase-modulation-distortion.

Abstract: A controller for controlling a signal processor includes a transformation unit and a control unit. The transformation unit is configured to generate at least one amplitude-modulation-to-phase-modulation-distortion within a signal, output by using the signal processor according to a signal processing, based on generated at least one amplitude-modulation-to-amplitude-modulation-distortion of the signal. The control unit is configured to adjust the signal processing of the signal processor so as to minimize the at least one amplitude-modulation-to-phase-modulation-distortion.

Abstract: There is described a method for checking the authenticity of security documents, in particular banknotes, wherein authentic security documents comprise security features (41-49; 30; 10; 51, 52) printed, applied or otherwise provided on the security documents, which security features comprise characteristic visual features intrinsic to the processes used for producing the security documents. The method comprises the step of digitally processing a sample image of at least one region of interest (R.o.I.) of the surface of a candidate document to be authenticated, which region of interest encompasses at least part of the security features, the digital processing including performing a decomposition of the sample image by means of wavelet transform (WT) of the sample image. Such decomposition of the sample image is based on a wavelet packet transform (WPT) of the sample image, preferably a so-called two-dimensional shift invariant WPT (2D-SIWPT).

Abstract: There is described a method for checking the authenticity of security documents, in particular banknotes, wherein authentic security documents comprise security features (41-49; 30; 10; 51, 52) printed, applied or otherwise provided on the security documents, which security features comprise characteristic visual features intrinsic to the processes used for producing the security documents. The method comprises the step of digitally processing a sample image of at least one region of interest (R.o.I.) of the surface of a candidate document to be authenticated, which region of interest encompasses at least part of the security features, the digital processing including performing a decomposition of the sample image by means of wavelet transform (WT) of the sample image.