I've solved this on Macintosh with NO special software (except Acrobat)
1. Open the PDF
2. Click on the image you want to copy
3. "Right-Click" and select Copy Image
4. Open preview
5. Select "File | new From Clipboard"
This will paste/create the image with Transparent background into the picture.
6. Click the "Show Markup Tool Button"
7. Select "Shapes" and create a white box that completely covers the image (Yes it will cover up the image you just pasted).
8. Select Edit | Paste
You now should have the image against a white background
9. File | Save...
Boom, you have a png file, with background that you can use.
Alternatively, you can open an image with a landscape in Preview and then paste the copied image on to that. Preview WILL handle it.