Figure 3.

Components of a NIfTI file: (a) A simplified illustration of the .nii file format, which stores both metadata (in the header) and image data (voxel intensities). The image data is stored as a matrix within the file. (b) A visualization of the 3D image matrix composed of voxels—small cubes that represent the spatial resolution of the scan, measured in mm³. The small red cube represents a voxel within the shown gray matrix. (c) The RAS coordinate system of the scans, where the x-, y-, and z-axes, illustrated by red arrows, correspond to the Right–Left, Anterior–Posterior, and Superior–Inferior directions, respectively.