About niiview

niiview is a Python3 based tool, which can display 3D and 4D .nii and .nii.gz files in terminals with sixel support. By default, it displays the middle of a NIfTI image with a selection of simple metrics. An interactive mode is also available, which allows for keyboard navigation through the different slices of the brain.

Terminals that support sixel:

Sixel is not widely supported among terminals. The following two are known to work:

• xterminal (in vt340 mode)
• iTerm2

Installation

1. makes sure your Terminal can display sixel (see above).
2. install libsixel (on Debian/Ubuntu systems:

sudo apt install libsixel-bin

3. install niiview (here we'll use a python virtual environment):

python3 -m venv ~/.venv/niiview
source ~/.venv/niiview/bin/activate
pip3 install git+https://github.com/psyinfra/niiview/
niiview file.nii.gz

Troubleshooting

The most common source of problems is getting your terminal to sixel-fy. Make sure that you are using a terminal that supports sixel, that it's configured correctly, and that the config is loaded correctly (some systems don't correctly, for reasons unknown. Sometimes the following helps: xrdb ~/.Xdefaults).

niiview is a young program, and there are many filetypes and modalities that it has not been tested with yet. Testing and feedback of failure and success is much appreciated.

Inspiration

Credit goes to niicat for the original idea to use sixel for quickly inspecting NIfTI images.

Huge thanks to Hayaki Saito, who brought Sixel — a forgotten gem of 80's technology — forward to modern systems.