To have Didger automatically create vector contour lines:
Click on the image to select it.
Click the Image | Vectorize Image command or click the button to open the Vectorize Image dialog.
Set the Edge Detection Method to Standard Object Thinning.
Set the Smooth Lines to Minor.
Set the Min Pixel Length to 5.
Uncheck the box next to the Auto Generate Polygons if it is checked.
Check the box next to the Create results on new layer(s) if it is not already checked.
Click OK and the vector polylines are automatically created from the image.
Back to Opening an Existing Project File
Next to Turning Off the Image Display