Engauge Digitizer - Digitizing Graphs
Complete Set of Steps To Digitize An Image File
The following steps manually digitize a linear cartesian graph with
one curve:
- Obtain an image file (bitmap, jpeg or other) showing one or more
graphs and both axes
- Import the image file using the File/Import menu option
- Click on the Axes Point button before entering axes points. These
will define the coordinate system
- Click on one of the axes to add the first axes point, then enter
its graph coordinates
- Click on one of the axes to add the second axes point, then enter
its graph coordinates
- Click on one of the axes to add the third axes point, then enter
its graph coordinates
- Click on the Curve Points button before entering curve points. These
will contain the digitized curve data
- Click on the curve to add a curve point
- Repeat the previous step until the curve is covered with a
sufficient number of curve points
- Export the curve points into a tabular text file using the
File/Export menu option
Alternate Steps
For speed, the graph can be automatically digitized, rather than
manually digitized, as follows:
- Click on the Segment Fill button before digitizing entire segments
with one click
- Click on a curve segment to automatically fill up the segment with
curve points
For a graph that is logarithmic or polar:
- Select the Settings/Coords menu option to bring up the
coordinates window
- Select the appropriate coordinate settings
For a graph with more than one curve:
- Select the Settings/Curves menu option to bring up the
curves window
- Click on the New button to create a new curve, then enter the
name of the new curve
- Repeat the previous step until all desired curve names have
been entered
- In the main window, use the Curves combobox to select a curve.
While that curve is selected, all new curve points will be assigned
to that curve