Comparing the crude looking of the original green/blue/white image with the sharp look of the
salmon/white image one can see that it worths the effort!!!
Step 1: Exporting the Background
Click in "Display" icon at Eagle pallete and then in "None" button. Then reselect the following layers
Click "Ok" button and you'll see the blue and green image of the bottom copper layer with pads and vias.
Click in File->Export, then select "Image"
Now check the "Clipboard" and "Monochrome" boxes and set the resolution to 300dpi. Then click Ok