Engauge Digitizer - Digitizing software

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This open source, digitizing software converts an image file showing a graph or map, into numbers. The image file can come from a scanner, digital camera or screenshot. The numbers can be read on the screen, and written or copied to a spreadsheet.

The process starts with an image file containing a graph or map. The final result is digitized data that can be used by other tools such as Microsoft Excel and Gnumeric.

Engauge (from en "make" and gauge "to measure") verb meaning to convert an image file containing a graph or map, into numbers.

The term "Engauge" in Engauge Digitizer was invented for this project, since there seems to be no similar term in common use.

Why Would You Need This Tool?

Here are some real-life examples:

  • You are an engineer with some graphs in decades-old documents, but you really need the numbers represented in those graphs so you can do analyses that will determine if a space vehicle is safe to fly.
  • You are a graduate student gathering historical data from charts for your thesis.
  • You are a webmaster with visitor statistics charts and you want to do statistical analyses.
  • You ride a bike or boat and want to know how much distance you covered in your last trip, but you do not have an odometer or GPS unit. However, you do have a map.

Nice Features

  • Automatic curve tracing of line plots
  • Automatic point matching of point plots
  • Automatic axes matching
  • Automatic grid line removal for improved curve tracing
  • Handles cartesian, polar, linear and logarithmic graphs
  • Support for drag-and-drop and copy-and-paste makes data transfer fast and easy
  • Image processing tools highlight data by removing grid lines and backgrounds
  • Status bar suggestions guide beginners
  • Context sensitive popup help windows reveal explain feature of the user interface
  • Tutorials with pictures explain strategies for common operations
  • Browser-based user manual is extensive yet easy to navigate
  • Preview windows give immediate feedback while modifying settings
  • Dates and times are imported with the Date/Time Converter
  • Import support for common image file formats such as BMP, GIF, JPEG, PNG and XPM
  • Export support for common software packages such as Microsoft Excel, OpenOffice CALC, gnuplot, gnumeric, MATLAB and Mathematica
  • Engauge is available for a wide variety of platforms (Linux, Mac OSX, Windows)
  • Engauge Digitizer is completely open source and free courtesy of Sourceforge, Trolltech and FFTW


Engauge Digitizer is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License (version 2) as published by the Free Software Foundation.


Engauge Digitizer was upgraded to Qt4 in late 2011 (thanks Tobias Winchen and Tobias Richter!). In version 5.1 some minor fixes were made, and point matching was fixed in Windows.

If you would like to monitor this software and receive email notification of new releases, click on the envelope icon on the Project Summary page. If you would like to suggest any new features, please use the Feedback page to privately contact the developers, or the Open Discussion forum.

Recent History

  • 12/23/2012 Engauge Digitizer 5.1 is released with a fix for broken point matching, and control of the x/theta axis label.
  • 10/28/2012 Engauge Digitizer is ranked #9636 in popularity among all of the Debian packages for short term users.
  • 10/4/2012 Jacob Egner fixes keyboard shortcuts, updates zoom levels and the file suffix list, and starts work on other new highly desirable features like contour construction!
  • 9/23/2011 Tobias Winchen makes extensive changes and successfully upgrades Engauge to Qt 4!
  • 4/20/2007 Engauge Digitizer wins "Download of the Day" award at lifehacker.com
  • 4/19/2007 Engauge Digitizer is released as part of the Universe collection of Ubuntu 7.04 (Feisty Fawn)
  • 4/11/2007 Engauge Digitizer 4.1 is released with the ability to move selected points using the arrow keys.
  • 1/2/2007 Engauge Digitizer 4.0 is released with faster and more powerful point matching, which fixes an overflow error that occasionally occurred in Ubuntu.
  • 11/19/2006 Engauge was accepted into the standard Debian distribution
  • 10/1/2006 Out of over 130,000 projects at Sourceforge, Engauge Digitizer spends three days among the top-ranked 300!