The 2D views

The axial, coronal and sagittal views each show one slice through the crosshair. Moving the crosshair in one view moves the slices of the others.

Moving around

Mouse or key	Does
Click or drag	Moves the crosshair there, and selects the view
Scroll, or Up and Down	Next or previous slice, one voxel of the main volume at a time
Ctrl + scroll, or pinch	Zooms about the pointer
Ctrl++ and Ctrl+-	Zoom in and out about the crosshair
Ctrl + drag	Pans
R	Shows the whole view again (zoom 1, centred)

Ctrl is Cmd on macOS. The keys act on the selected view, whose thin frame is in the accent colour.

The crosshair and the readout

The top-left corner names the view and its slice of the main volume, counted from 0 as the voxel is: “Axial z 124 / 260” is slice 124 of 260 along z. The text in the bottom-left corner is the readout: the main volume’s name, its value at the crosshair, the voxel (with the volume index last for a 4D image) and the position in mm. The letters at the edges give the orientation: R and L, A and P, S and I. X shows or hides the crosshair, and I the text, the letters and the colour bars; both are also in the View menu.

RAS and LAS

By default the views follow the neurological convention (RAS): the subject’s right is on the right of the screen. The radiological convention (LAS) puts it on the left in the axial and coronal views. Change it with Display convention in Settings.

One view at a time

The button in a view’s top-right corner, or a double click in the view, makes that view fill the window; do it again to show all four. The keys A, C, S and 3 do the same for the axial, coronal, sagittal and 3D views.