Search results
Results From The WOW.Com Content Network
F. Autrusseau and J. Guédon, “Image watermarking for copyright protection and data hiding via the Mojette transform,” in Security and Watermarking of Multimedia Contents IV, 2002, pp. 378–386. F. Autrusseau and J. Guédon, “Image Watermarking in the Fourier Domain Using the Mojette Transform,” in Digital Signal Processing, 2002, pp ...
His postdoctoral work at Trinity College Dublin and at the University of Geneva concentrated on the then-emerging field of digital watermarking. He published seminal papers on image transform domain watermarks and, in particular, rotation and translation invariant watermarks based on the Fourier transform. [2]
The 2D Z-transform, similar to the Z-transform, is used in multidimensional signal processing to relate a two-dimensional discrete-time signal to the complex frequency domain in which the 2D surface in 4D space that the Fourier transform lies on is known as the unit surface or unit bicircle.
It is a shaded watermark first used in 1848 that incorporates tonal depth and creates a greyscale image. Instead of using a wire covering for the dandy roll, the shaded watermark is created by areas of relief on the roll's own surface. Once dry, the paper may then be rolled again to produce a watermark of even thickness but with varying density.
Formally, the optical transfer function is defined as the Fourier transform of the point spread function (PSF, that is, the impulse response of the optics, the image of a point source). As a Fourier transform, the OTF is generally complex-valued; however, it is real-valued in the common case of a PSF that is symmetric about its center.
Phase correlation is an approach to estimate the relative translative offset between two similar images (digital image correlation) or other data sets.It is commonly used in image registration and relies on a frequency-domain representation of the data, usually calculated by fast Fourier transforms.
An example application of the Fourier transform is determining the constituent pitches in a musical waveform.This image is the result of applying a constant-Q transform (a Fourier-related transform) to the waveform of a C major piano chord.
A DCT is a Fourier-related transform similar to the discrete Fourier transform (DFT), but using only real numbers. The DCTs are generally related to Fourier series coefficients of a periodically and symmetrically extended sequence whereas DFTs are related to Fourier series coefficients of only periodically extended sequences.