python压缩图片,Python图像库（PIL），如何将图像压缩成所需的文件大小？

Dear 丶 2023-01-24 02:15 18阅读 0赞

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I got a requirement to compress any uploaded images less than 500kb in file size, I have searched on google and all I can see is:

>>> foo = foo.resize((160,300),Image.ANTIALIAS)

>>> foo.save("path\\\\to\\\\save\\\\image\_scaled.jpg",quality=95)

If I go with this approach I will have to check if the image is less than 500kb after compress, if not then go for lower quality and size.

Is there a better way to do it?

解决方案

JPEG compression is not predictable beforehand. The method you described, compress & measure & try again, is the only way I know.

You can try compressing a number of typical images with different quality settings to get an idea of the optimum starting point, plus a way of guessing how changes to the setting will affect the size. That will get you to zero in on the optimum size without too many iterations.

You can also pass a file-like object to the save function that doesn't bother to write to disk, just counts the bytes. Once you've determined the best settings then you can save it again to an actual file.

Edit: Here's an implementation of a suitable byte counting file object. Just check size after the save.

class file\_counter(object):

def \_\_init\_\_(self):

self.position = self.size = 0

def seek(self, offset, whence=0):

if whence == 1:

offset += self.position

elif whence == 2:

offset += self.size

self.position = min(offset, self.size)

def tell(self):

return self.position