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Isaac Amidror

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Publications associées (40)

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Tutorial: Sub-Nyquist artifacts and sampling moiré effects

Isaac Amidror

Sampling moiré effects are well known in signal processing. They occur when a continuous periodic signal g(x) is sampled using a sampling frequency fs that does not respect the Nyquist condition, and the signal frequency f folds-over and gives a new, false ...

The Royal Society Publishing2015

Sub-Nyquist artifacts and sampling moiré effects, Part 2: Spectral-domain analysis

Isaac Amidror

Sampling moiré effects occur due to aliasing (foldover) when a continuous periodic signal g(x) is sampled using a sampling frequency that does not respect the Nyquist condition. However, visible beating artifacts may also occur when g(x) is sampled using s ...

2015

Analytic derivation of the (k/j)-order modulation envelopes in the sum of two mistuned (co)sine waves

Isaac Amidror

The beating effects which may occur in the sum of two mistuned cosine (or sine) functions whose frequencies f1, f2 satisfy f2 ≈ (k/j)f1 (where k/j is a reduced integer ratio) are known as “beats of mistuned consonances”. They have already been investigated ...

2015

Jaggies as aliasing or reconstruction phenomena: a tutorial

Roger Hersch, Isaac Amidror

Jaggies (staircasing effects) along slanted lines or curved edges are omnipresent in digital imaging. They are so widespread in digital display devices that very often they are associated with the modern "computerized" world (and sometimes even intentional ...

Is&T & Spie2014

Mathematical moiré models and their limitations

Roger Hersch, Isaac Amidror

In a previous recent paper we discussed the limitations of the Fourier-based model in the prediction of visible moiré effects. Here, we extend the discussion to other mathematical models that are also being used in the moiré theory: the classical indicial ...

2010

Modern moiré theory is largely based on the Fourier approach. And yet, it seems that the Fourier theory by itself cannot answer all questions related to moiré effects. We present some visible phenomena in the superposition of periodic structures (such as l ...

2009

This invention discloses new methods and security devices for authenticating documents and valuable products which may be applied to any support, including transparent synthetic materials and traditional opaque materials such as paper. The invention relate ...

2009

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Moiré effects have long been used for various applications in many different fields, including metrology, strain analysis, optical alignment, etc. In the present survey we describe some of the main applications of the moiré effect in the field of document ...

2007

Diffractive moire features for optically variable devices

Roger Hersch, Isaac Amidror, Sylvain Chosson

We present diffractive second-line security features based on the moire phenomenon, that are designed for use in Optically Variable Devices (OVDs). After a short introduction of our 2D and 1D moire methods, we first present the integration of line-based, 1 ...

International Society for Optical Engineering, Bellingham WA, WA 98227-0010, United States2006

This invention discloses new methods, security devices and apparatuses for authenticating documents and valuable articles which may be applied to any support, including transparent synthetic materials and traditional opaque materials such as paper. The inv ...

2006