python PIL save image different size original
Question: I´m working on a project with PIL in python. Simply by opening and saving an
image makes the output image bigger (in Bytes) than the original, maintaining
the same resolution, and i don´t know why...

    
    
    from PIL import Image
    img = Image.open("photo.png")
    img.save("photo2.png", "PNG")
    

[result from code above](http://i.stack.imgur.com/23Mba.png)

Does any one have any idea why this happens? i need them to be exactly the
same.


Answer: PNG is a compressed lossless format. The original image was probably saved
with different compression settings.

Looking at the
[documentation](http://pillow.readthedocs.org/en/3.0.x/handbook/image-file-
formats.html#png) you could try:

    
    
    img.save("photo2.png", "PNG", optimize=True)
    

or

    
    
    img.save("photo2.png", "PNG", compress_level=9)
    

By default, `compress_level=6` is used.

Note that the `optimize` option _includes_ setting the compression level to 9.
But it also tries to find optimal encoder settings.

