 Engauge Digitizer - Digitizing Point Graphs
  Engauge Digitizer - Digitizing Point Graphs
| Warning: Not all point graphs work well when automatically matching points
in Engauge. Before going any further, you may want to read about 
point match requirements. | 
Typical Set of Steps To Digitize Point Graphs
The following steps digitize a linear cartesian graph with 
points along one curve:
- Obtain an image file (bitmap, jpeg or other) showing one or more 
graphs and both axes
- Import the image file using one of the following options:
  
  - File/Import menu option
- Copying and pasting
- Dragging and dropping
 
- 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 Point Match button
to automatically digitize many
curve points.
- Click on a sample point, and then use the arrow keys to accept
or reject points that match the sample point.
- Click on the Curve Points button to manually enter curve points.
- 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 curve points using one of the following options:
  
  - File/Export menu option to save selected 
  curves into a tabular text file
- Copying and pasting to copy points in the current curve from the 
  curve geometry window to another application
- Dragging and dropping to copy points in the current curve from the 
  curve geometry window to another application
 
Optional Steps
To clean up the image for better performance of
Segment Fill and Point Match:
steps:
- Show the processed image, rather than the original image, by
selecting the View/Background/Show Filtered Image menu option
- Adjust the discretize settings using the Settings/Discretize
menu option, until unwanted parts of the image disappear
- Remove grid lines using the Settings/Grid Removal
menu option
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