Convert PNG with Transparency to JPG http://librelist.com/browser//wand/2013/9/8/convert-png-with-transparency-to-jpg/

gistfile1.py

from wand.color import Color
from wand.image import Image


with Image(filename='tests/assets/trimtest.png') as png:
    with Image(width=png.width,
               height=png.height,
               background=Color('white')) as jpeg:
        jpeg.composite(png, 0, 0)
        jpeg.save(filename='result.jpg')