Gaussian approximation of a rectangular pulse Some image processing methods inherently smooth the images with an ideal filter, that is, a rectangular pulse. Comparing those methods with others that use a more typical Gaussian kernel can thus be challenging, as even if the full-width at half-maximum (FWHM) of the Gaussian filter is made equal to the width of the rectangular pulse, the resulting smoothnesses are not similar.

Some image processing methods implicitly smooth images with an ideal filter. What's the FWHM of the Gaussian filter that produces the most similar degree of smoothing?

Uniform directions for multi-shell diffusion MRI This post describes a reimplementation of the method described by Caruyer et al. (2013). If you already know what this is about, you can skip the information below and simply grab the code on GitHub: multishell.py. If you don't know, a good place to start is Tuch et al. (2004). Background When we plan a magnetic resonance imaging protocol, we often have to balance what we would like to have in terms of quantity and quality of images, versus what can realistically be obtained within limited time slots (e.g., 30 minutes or 1 hour) while minimizing discomfort to the research participants, most of whom would rather not spend more than an hour in a somewhat uncomfortable MRI exam table.

A script to define optimal directions in multishell diffusion MRI and prepare files for different scanners.

Fiat lux.