js9

v3.8.0

Published

2 years ago

astronomical image display everywhere

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ericmandel

astronomy software image display

My software career comes to an end on July 1, 2022 and with it will end active development of JS9. Please plan accordingly. Eric

JS9: astronomical image display everywhere

JS9

What does it do?

display FITS images, binary tables, data cubes, and multi-extension files
colormaps, scaling, pan, zoom, binning, blending, print, export ...
region support: create, manipulate, import, export, ...
drag and drop images, regions, catalogs
server-side and local analysis using the JS9 public API
control JS9 using scripts from the Linux shell or Python
runs on Macs, Linux, Windows, iPads, iPhones, ...
runs as a Desktop app in all modern browsers
utilizes WebAssembly (FITS processing at near native speed!)

How can I try it out?

Go to JS9 web site and drag a FITS data file onto the JS9 display:

https://js9.si.edu

You can even specify a remote FITS file and associated image display parameters as part of the URL:

https://js9.si.edu/js9/js9.html?url=https://hea-www.cfa.harvard.edu/~eric/coma.fits.gz&colormap=cool

The JS9 web site also contains on-line documentation, demos, and release downloads.

To install or not to install ...

For many users, there is no need to install JS9: simply use the JS9 web site to display your data. You can even upload your FITS files to the web site and run our server-side analysis.

Installing JS9 allows you to create your own web pages, tailor site parameters, and add your own local and server-based analysis tasks. Grab the latest version from JS9 on GitHub:

git clone https://github.com/ericmandel/js9

Load a local page into your browser:

file:///path/to/js9/js9.html

(NB: Chrome needs to run with the --allow-file-access-from-files switch to use the file URI.)

For Desktop use, install Electron.js and use the js9 script to start the Desktop app and load an image:

js9 -a ~/data/m13.fits

For more advanced support (web-based support, support for handling large files), build the JS9 helper and install JS9 in a web directory:

# configure location to install the JS9 web files,
# where to find cfitsio library and include files,
# where to install programs and scripts,
# what sort of helper to build:
./configure --with-webdir=[path_to_web_install] \
            --with-cfitsio=[path_to_cfitsio]    \
            --prefix=[path_to_prog_install]     \
            --with-helper=nodejs

# the usual ...
make
make install

# start helper
cd path_to_web_install
# in the bash shell:
node js9Helper.js 1>~/logs/js9node.log 2>&1 &
# or, in the tcsh shell:
node js9Helper.js >& ~/logs/js9node.log &

What about scripting?

The js9 script allows you to control a JS9 web page from the Linux command line using the JS9 Public API (scripting requires installation of JS9 and either node.js or Electron.js):

js9 Load chandra.fits '{"scale":"log","colormap":"red","contrast":5.78,"bias":0.15}'
js9 Load spitzer.fits '{"scale":"log","colormap":"blue","contrast":6.3,"bias":0.54}'
js9 ReprojectData chandra.fits

Python users can install pyjs9:

git clone https://github.com/ericmandel/pyjs9
...
import pyjs9
j = pyjs9.JS9()
j.Load('chandra.fits', '{"scale":"log","colormap":"red","contrast":5.78,"bias":0.15}')
j.Load('spitzer.fits', '{"scale":"log","colormap":"blue","contrast":6.3,"bias":0.54}')
j.ReprojectData('chandra.fits')