`libsixel-python` is missing.

[fepegar]

$ niicat icbm_avg_152_t1_tal_nlin_symmetric_VI.nii.gz 
`libsixel-python` is missing. See https://github.com/saitoha/libsixel

$ pip install libsixel-python    
Requirement already satisfied: libsixel-python in /Users/fernando/miniconda3/envs/episurg/lib/python3.6/site-packages (0.5.0)

$ niicat icbm_avg_152_t1_tal_nlin_symmetric_VI.nii.gz 
`libsixel-python` is missing. See https://github.com/saitoha/libsixel

$ ipython                  
Python 3.6.7 | packaged by conda-forge | (default, Jul  2 2019, 02:07:37)
Type 'copyright', 'credits' or 'license' for more information
IPython 7.6.1 -- An enhanced Interactive Python. Type '?' for help.

In [1]: import libsixel
---------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
<ipython-input-1-7b2ccdc20b41> in <module>
----> 1 import libsixel

~/miniconda3/envs/episurg/lib/python3.6/site-packages/libsixel/__init__.py in <module>
    350
    351 if not find_library('sixel'):
--> 352     raise ImportError("libsixel not found.")
    353
    354 # load shared library

ImportError: libsixel not found.

[wasserth]

Apparently the libsixel-python does not properly work on your system. Please create a ticket on https://github.com/saitoha/libsixel for this. Alternatively you can run niicat with the option -ic if you are on iTerm2, or install libsixel as binary (without python) and use the option -lb. This might work for you.

[Timiain]

meet too