Automatically Convert PNG to JPG with Python

I've written a Python program to retrieve an image from a URL using

msgImage = MIMEImage( urllib2.urlopen(chartURL).read() )
msg开发者_如何转开发Root.attach(msgImage)

The image that I get from the URL is in PNG format, but I would like to embed a JPG version of it. Is there a simple way to automatically convert the PNG msgImage into JPG for smaller attachments?

Thanks for reading. Any help is greatly appreciated.

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You can use PIL: http://www.pythonware.com/products/pil/ It is easy and it has a lot of documentation.