Conceived for functional Magnetic Resonance Imaging, create_mosaic may also be useful for DWI or other applications which create image time-series

Most fMRI programs use 4D matrices (x,y,z,t) in NIfTI format.
It can be useful to reduce the number of dimension from 4 to 3 by tiling all slices (z) into a "mosaic" image for each time point (t).
Scrolling through the 3rd dimension in the mosaic (e.g. in mricro http://www.cabiatl.com/mricro/mricro/index.html) allows the time course of each slice to be visualised.
Useful for assessing motion and artefacts in fMRI time series.
Can also be used to create a 2D mosaic of all the slices in a 3D volume, e.g. for structural imaging

In the example below, 4D EPI times-series in NIfTI format (all called 'Image.nii') are stored in the directories '5','6','8' in the directory specified by root_dir
create_mosaic writes a 3D mosaic file for each, in NIfTI format, in the directory results_dir, with file names Mosaic_5.nii, etc

Simon Robinson. 2/May/2011. simon.robinson@meduniwien.ac.at
version_number = 1.0;
Credit: includes many functions from Jimmy Shen's excellent NIfTI toolbox (file exchange # 8797)