How to convert Image to PIL.Image

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How do you convert a ROS Image message data to a PIL Image?

I found code that works for CompressedImage, but it fails for the normal Image data type:

def convert(msg):
    import io
    from PIL import Image
    return Image.open(io.BytesIO(bytearray(msg.data)))

which gives me the error:

IOError: cannot identify image file

I tried the cv_bridge component, since it's trivial to convert a CV image to PIL, but when I tried:

def convert(msg):
    import cv2
    bridge = CvBridge()
    cv_image = bridge.imgmsg_to_cv2(msg, "rgb8")
    cv2.imwrite('sample.jpg', cv_image)

I get a mangled image like:

What am I doing wrong?

Edit: It seems I can't even view the raw stream using image_view. If I run:

rosrun image_view image_view image:=/camera/image

it gives me the error:

[ERROR] [1458436979.679038299]: Unable to convert 'bgra8' image for display: 'Image is wrongly formed: height * step != size  or  240 * 1360 != 337920'

What's wrong with my video stream?