Context: in large-scale spatial surveys, the Point Spread Function (PSF) varies across the instrument field of view (FOV). Local measurements of the PSFs are given by the isolated stars images. Yet, these estimates may not be directly usable for post-processings because of the observational noise and potentially the aliasing. Aims: given a set of aliased and noisy stars images from a telescope,...

The accuracy of gradient-based optical flow algorithms depends on the ability to measure intensity gradients accurately. We show how the temporal gradient can be compromised by temporal aliasing arising from motion and how appropriate post-sampling spatial filtering improves the situation. We also demonstrate a benefit of using higher-order gradient estimators.

The CAIPIRINHA (Controlled Aliasing In Parallel Imaging Results IN Higher Acceleration) concept in parallel imaging has recently been introduced, which modifies the appearance of aliasing artifacts during data acquisition in order to improve the subsequent parallel imaging reconstruction procedure. This concept has been successfully applied to simultaneous multi-slice imaging (MS CAIPIRINHA). I...

When using a gradient-based method to determine the optical flow field for an image sequence, it is generally appreciated that some spatial pre-filtering of the images is usually needed, particularly for large motion values. However the characteristics of the filter are not generally given. In this paper we analyse the motion measurement from the point of view of sampling theory. We show how an...

Dedicated to the memory of my father, who always pushed me to adquire more knowdlege, while supporting me in doing what I always wanted to do. I will never forget you. Dedicated to the memory of Kazan, who spent countless hours behind me, quietly observing how this thesis was maturing. I will always miss you. Dedicated to my mother, for its eternal love and support. Thanks for being the best mo...

Direction-of-arrival (DOA) estimation is widely applied in acoustic source localization. A multi-frequency model suitable for characterizing the broadband structure signals. In this paper, continuous (gridless) DOA problem with multiple frequencies considered. This formulated as an atomic norm minimization (ANM) problem. The ANM equivalent to a semi-definite program (SDP) which can be solved by...

Combining Doppler and polarimetric information is advantageous for atmospheric studies. On the one hand, Doppler information gives insight into the microphysical and dynamic properties of radar targets, that is, radial velocity and its variability. The polarization diversity, on the other hand, has a strong link to the microphysical properties of targets such as shape and orientation. Polarimet...

Type-based alias analyses allow C compilers to infer that memory locations of distinct types do not alias. Idiomatic reliance on pointers on the one hand, and separate compilation on the other hand, together make it impossible to get this aliasing information any other way. As a consequence, most modern optimizing C compilers implement some sort of type-based alias analysis. Unfortunately, poin...

Multirate iterative learning control (ILC) systems have different sampling rates for feedback online loop and feedforward (or ILC) offline loop. The implementation of multirate ILC requires to downsample the signal first and, after processing, upsample the signal again. In the process of downsampling and upsampling, aliasing and imaging may occur and need to be handled properly. In this paper, ...