The aim of this chapter is to review: (1) the Sampling (Nyquist) Theorem; (2) the concept of aliasing; (3) the importance of antialiasing low-pass filtering for eliminating the effect of aliasing and appropriately determining the sampling frequency; (4) the advantages of properly chosen ...
What is the aliasing effect? The aliasing effect is a measurement error in the signal occurring due to an incorrectly set sampling rate. If the sampling rate is too low, the Nyquist-Shannon sampling theorem is not observed and thus the measurement signal is not acquired correctly. ...
The aliasing phenomenon is not confined to MRI but is present in all types of technology, explaining audible distortions of sound, moire patterns in photos, and unnatural motion in cinema. The "wagon wheel effect" is a familiar example of aliasing. In this optical illusion, spokes on a wheel...
highly visible in repetitive patterns such as fabrics. Demosaicing programs (programs that fill in the missing colors in the raw image) use sophisticated algorithms to infer missing detail in each color from detail in the other colors. These algorithms can have a significant effect on color moiré...
ShanghaiInstituteofTechnology SchoolofMechanicalEngineering Chapter6Anti-aliasingMethodsandSampling Strategies Introduction: LastChapter5showedhowtoestimatethemaximumsamplingrateofan hardwareacquisitionstructure,startingfromitscharacteristicfeatures.The samplingtheorem,discussedinChapter3,provesthat,inordertoensurea correct...
noise ratio). Narrow receive bandwidths accentuate thiswater fat shiftby assigning a smaller number of frequencies across theMRIimage. This effect is much more significant on higher field strengths. At 1.5 T, fat and waterprecess220 Hz apart, which results in a higher shift than inLow Field ...
So far, we've explored thetheoretical underpinnings of the Nyquist-Shannon theorem, including thefrequency domain effect on sampling. We then touched on how these foundational principles apply in real-life circuit design—specifically, addressing the importance ofoversampling in real-life mix...
2011on that topic and its usage in Crysis 2 [1]. Crytek proposed using a sub pixel jitter to the final MVP transformation matrix that alternates every frame – and combine two frames in post-effect style pass. This way they were able to increase the sampling resolution twice at almost no...
Aliasing is an effect that causes distortion in the spectrum of a sampled signal due to the sampling rate being too low to capture the frequency content properly. Aliasing causes high frequency data to appear at a lower frequency than it actually is (seeFigure 1below): thus assuming a “fals...
increased levels of random perturbation because of this aliasing, causing an increase in the mean-square error due to ‘misadjustment’, as discussed inChapter 2. Unless the controller is being adapted very quickly, however, the degradation in performance due to this effect is likely to be ...