Using Image.rotate, I found that it didn't do what I expected from it particularly with n*90 angles (and I don't think it's supposed to work this way either :) )
The image got shifted, part of it being cropped, black background being revealed and dimension is slightly modified.
Transpose does work though.
Here is test script showing issue :
#!/usr/bin/env python
import Image, ImageDraw
#im = Image.new("L", (928, 151), 128)
im = Image.new("L", (928, 140), 128)
draw = ImageDraw.Draw(im)
draw.rectangle([0,0,im.size[0]-1,im.size[1]-1], outline=255, fill=128)
del draw
im.save("im_orig.png")
rotated = im.rotate(180, resample=Image.BICUBIC, expand=1)
rotated.save("im_rotated.png")
transposed = im.transpose(Image.ROTATE_180)
transposed.save("im_transposed.png")
