PIL Image Convert from RGB to YCbCr Results in 4 Channels Instead of 3 and Behaves Like RGB

https://mail.python.org/pipermail/image-sig/2010-October/006526.html

It's an old bug with Numpy. To correct it

>>> import numpy
>>> import Image as im
>>> image = im.open('bush640x360.png')
>>> ycbcr = image.convert('YCbCr')

>>> B = numpy.ndarray((image.size[1], image.size[0], 3), 'u1', ycbcr.tostring())
>>> print B.shape
(360, 640, 3)
>>> im.fromarray(B[:,:,0], "L").show()