1. Import an image file to digitize.
2. Pick three points on the axises to define the X and Y axis (those can be for cartesian, polar, linear and logarithmic graphs).
3. You can clean-up your image by features like automatic grid removal, and discretize. The discretize is very helpful in cleaning up the image, where you can specify various thresholds with real time preview of the image.
4. You then face two choices – manual and automatic digitizing process.
5. Finally when happy with the results – you can export the data to a .csv file to be processed with other software.

Overall I find it a very useful freeware program especially for engineers, scientists and students, where very often it is helpful to digitize data from a plot, scanned from a book. It is a powerful software with a very good set of automatic detection tools.

You can also make different types of function plots, analyze intersections, minima, maxima. Logarythmic plots are also available. Plotting multiple functions on the same plot is a breeze.

The user interface is very intuitive and easy to use. The work area is syntax highlighted which helps to identify variables, functions, answers, etc. On the right side a library with the integrated functions and constants is available. The program has a very nice and well written help file.