Inserting text notes and dimensions	Notes, labels and images
How to change the line color of the background image
Concepts     Procedure     Commands

Using the Format menu Background Image  Set line color of background Image    it is possible  to modify the line color of the background image.  

The control will open a window in which the new color can be set.

  Menu :  Format Background Image  Set line color  of background Image

Also see:

How to calibrate the background image

How to insert a background image in the drawing

How to remove the background image