用Python压缩图像（无存档）

Question

I'm writing a Python script that deals with images. Is there a module that can compress an image without putting it into an archive, and decompress it back? (eg A 1MB image is now 0.8MB after compression, then 1MB after decompression).

Can I see example code of compressing and decompressing an image in Python without the use of archives?

I've already taken a look at some modules, but those compress strings.

Answer 1

You probably want to take a look at the Python Image Library (PIL) , and the PNG and JPEG formats.

The PIL Image.save() method will let you save PNG or JPEG images.

PNG - Lossless, good for "cartoony"/logo images with solid colors or small numbers of colors.

JPEG - Lossy, good for photos, images with lots "going on".

Answer 2

Modern image formats such PNG and JPEG are already compressed and my general recommendation is take Brendan Long's advice and use those formats and exploit all the work that's been put into them.

That said, if you want to compress the contents of any arbitrary file in Python, here's a very simple example:

import zlib

with open("MyImage.jpg", "rb") as in_file:
    compressed = zlib.compress(in_file.read(), 9)

with open("MyCompressedFile", "wb") as out_file:
    out_file.write(compressed)