Technical drawing scans

After drawing and scanning our upper and lower case letters, I’ve realized that it is not easy to get a good scan of a technical drawing with construction lines.  In order to still see the construction lines, the brightness and contrast can only be adjusted so much. Martha warned us that getting a good scan of a technical drawing would be hard and I am definitely realizing that.  To have all of my lines visible, the background color of the scans is not appearing completely white.  I am definitely interested in going back and redrawing the letters with all the lines darker so the scans can have a white background with visible construction lines.