This is a planning page for the in-development Spectral Workbench API.

Purpose

The API (starting with the macro system, below) will it possible for anyone to develop new functions, like:

• displaying a set of wavelengths (and their intensities) for, say, a contaminant you're looking for
• displaying a ratio of wavelength x to wavelength y -- say, for normalized differential vegetation index (NDVI)
• display intensity at 600nm and indicate intensity at 600nm for the last 10 measurements
• calling up, averaging, and displaying the average of all spectra tagged with "oliveoil" or whatever
• graph intensity at wavelength X over time, for the past Y weeks
• save spectra periodically
• develop a better spectrum matching function (find nearest match)
• make a function which can auto-recognize a CFL spectrum and offer to auto-calibrate

Macros

We're going to start with a simple macro language, probably initially in a sandbox so people can try things out. We'll build out this language for a bit, let it stabilize, and then tackle the problems of publishing macros and sharing them amongst users. You can try the API out now (but not yet save macros) at https://spectralworkbench.org/capture

Getting started

To create a macro we'll have a simple editor you can enter JavaScript code into. At first you won't be able to save, and it'll just be a console "sandbox". The basic template will look something like this:

setup: function() {
    // code to run on startup
    $W.add_button("My Button",function(){ do_something() })
  },
  draw: function() {
    // code to run every frame
  }

A very simple command to run in the macro console (works as of Oct 14 2012) would be:

setup: function() { window.open($W.canvas.toDataURL(),'_newtab').focus()}

Which opens a new tab with the current image data as a PNG. For now, you can use any of the below variables and methods in a Javascript console such as found in Chrome, Safari, or Firebug on Firefox.

Variables and methods

A range of variables and methods will be available to use in your macros. To start with, you can read through the existing framework here:

https://github.com/jywarren/spectral-workbench/blob/master/webserver/public/javascripts/capture.js

• $W.data - returns a nested array of wavelength/intensity pairs, as floats and integers between 0-255, respectively. Example to come; intensities are separated by R, G, and B channels.
• $W.mode - "rgb" or "average", i.e. whether we're currently looking at color channel data or the averaged "monochrome" data
• $W.markers - an array of markers at certain wavelengths, as input by the user. Later we'll make it easy to add new markers (see upcoming section below)
• $W.notify(string msg,string type,boolean expire) - alert the user with a message (msg) of type "notify", "warning" or "error" shown in green, yellow, or red respectively. Defaults to expire = true, which means it disappears after 2 seconds.

• $W.getIntensity(obj data,int x) - Get the intensity from 0-255 for a given x-position in the video frame. Use as follows:

  $W.getIntensity($W.data[0].data,200) // fetches intensity for x-position of 200 px

• $W.saveSpectrum() - saves the current spectrum of data and brings up the Save dialog.

• $W.getWavelength(int col) - returns wavelength as a decimal for the x-axis position given in "col"
• $W.toggle_mode() - switch from "rgb" to "average" mode or back
• $W.show_rgb() - switch from "average" to "rgb" mode
• $W.show_average() - switch from "rgb" to "average" mode
• $W.add_spectrum(int id) - fetches data from a spectrum with the given ID, and displays it in the graph for comparison
• $W.excerptCanvas() - returns a PNG (data url) of the current waterfall display image

Upcoming variables and methods

• $W.add_button(string label,function action) - adds a new button to the interface which has the given label and triggers the given action
• $W.add_marker(string name,int wavelength) - not yet implemented - add a new marker to monitor the intensity at this wavelength.

Examples

Please add your own if you like:

Saving image data offline