Public Lab Wiki documentation

Spectral Workbench Help

This is a revision from August 17, 2012 13:09. View all revisions
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Getting started


What's "wavenumber" vs "wavelength"?

Wavenumber is the inverse of wavelength, and some scientists prefer it (depending on what their background is). It means the # of waves per distance -- I believe we're using lines per centimeter. Wikipedia has a kind of esoteric but detailed explanation:


If you have trouble, you can post questions to the mailing list by signing up on this site, which will subscribe you. You can also post requests for help to Github at:

Look over the issues listed here, and see if your problem already exists, or is already answered:

Spectral Workbench Issue Tracker

Known issues

Linux app wont boot - this may be due to the absence of the GSVideo library. Copy the folder called "libraries" from your /spectral_workbench/ directory into your Processing "sketchbook". It should contain the GSVideo library and the ControlP5 library. Now restart Processing or reopen the app.

Please consider these questions in your request:

  • Did you launch the platform-specific version in the Mac OS X or Windows folders, or run it from within Processing (
    • If you're having trouble, please try the Processing version, as it generates more useful error output.
  • If you run it in Processing ( can you copy and paste the debug output from the Processing window and post/send it? That's much easier to diagnose.
  • Do you have a webcam and does it work normally in Photo Booth (mac), Cheese (linux), VLC (windows and linux) or whatever webcam app Windows has?
    • Did you close other webcam-using applications and free up your webcam before launching Spectral Workbench?


Follow these instructions for full installation on Windows XP and Windows 7. (If you have time to tidy these instructions up and copy them into this wiki, even better!)

Mac OS X

  • What version of Mac OS X are you using?
  • If you see a grey screen, does a your webcam light up for a moment? There is a bug where a popup window asks you to choose a camera, but it can't come to the front because the app is fullscreen. You might try apple-tab once you see the green light come on.