This opaque Jpeg image was sent to me unsolicited by the badge maker for the 2006 Hillman National Rally :

I used Adobe Photoshop version 4 (pre-cambrian) :
  1. Select the Magic Wand Tool and click on the surrounding black area, then
  2. "Edit –> Fill" white (the default "background colour") into it

I then used Microsoft Office 2000 "Photo Editor version 3" to convert all white areas to transparent :
  1. Select the Set Transparent Color tool in the standard toolbar, then
  2. Click on a white area (any white will do).  Set the Color Similarity to "Within 3%" and Transparency to 100%