Extract Data From Figures

#notes #Data #Figure

This blog notes some free available softwares to extract data from a figure.

WebPlotDigitizer

WebPlotDigitizer was developed to be an easy to use, free of charge and opensource program that can work with a variety of plot types and images. This program is developed using HTML5 which allows it to run within a web browser and requires no installation on to the user’s hard drive.

DataThief

DataThief III is writen in Java. This means, that apart from the “excutable” called Datathief.jar, one will has to have the Java Virtual Machine. To use it, the basic steps are:

  1. Load the figure includes expected data;
  2. Fix the three location indicators (these have an X through there center) until the vertical quality indicator bar turns from red to fully green. This will allow you define the axe. One can also use log axe with well choose axis option from Axis menu;
  3. Once you have defined the axes, scattered data or full curve can be obtained from Point mode or Trace mode. To extract a curve, one also need define the start indicator, end indicator and color indicator.

One defect of DataThief is the extraction of a line with marker. In this case, if the output distance is too small, the matched curved will go along the edge of the marker (big error if the marker is not too small).

Engauge Digitizer

Engauge Digitizer, like DataThief, works on Linux, Mac and Windows. The process is import an image file, digitized within Engauge, and exported as a table of numeric data to a text file. Work can be saved into an Engauge DIG file.