Crop 4:3 picture to 16:9 without losing EXIF metadata

crop.py

#!/usr/bin/python

from PIL import Image
from pyexiv2 import ImageMetadata

def is16to9(img):
    img.size
    return img.size[0] * 9 == img.size[1] * 16

def cropTo16to9(img):
    original_size = img.size
    if is16to9(img):
        cropped_img = img
    else:
        width = original_size[0]
        height = original_size[0] * 9 / 16
        upper = (original_size[1] - height) / 2
        box = (0, upper, width, upper + height)
        cropped_img = img.crop(box)
    return cropped_img

def copyExif(src_path, dest_path):
    if src_path == dest_path:
        return

    src_img = ImageMetadata(src_path)
    src_img.read()
    dest_img = ImageMetadata(dest_path)
    dest_img.read()
    src_img.copy(dest_img)

    img = Image.open(dest_path)
    dest_img["Exif.Photo.PixelXDimension"]= img.size[0]
    dest_img["Exif.Photo.PixelYDimension"]= img.size[1]
    dest_img.write()



import os
from optparse import OptionParser

parser = OptionParser()
parser.add_option("-q", "--quality", type="int", dest="quality",
                    default=100, help="quality of the JPEG compression")
parser.add_option("-i", "--input", type="string", dest="ifname",
                    help="inout file name")
parser.add_option("-o", "--output", type="string", dest="ofname",
                    help="outout file name")

opts, args = parser.parse_args()
ifname = opts.ifname
quality = opts.quality
ofname = opts.ofname

if ifname == None:
    parser.print_help()
    exit()

if ofname == None:
    basename, ext = os.path.splitext(os.path.basename(ifname))
    ofname = basename + "_crp" + ext

img = Image.open(ifname)
cropped_img = cropTo16to9(img)

print img.size
print cropped_img.size

cropped_img.save(ofname, "JPEG", quality=quality)
copyExif(ifname, ofname)