Python PIL将图像保存在目录中，如果名称相同则不覆盖

Question

I am trying to make a backup copy of an image, because it will be resized often. I am asking for the path where the image is (Tkinter), then I am adding to the path and the image an "-original" and save it in the same directory where I got it from.

The problem is everytime I use this function it overrides the original, because there is no loop which makes the programm check wheter there already exists a file with "-original".

Thats how I make the backup save:

        pfad = askopenfilename()
        im_backup = Image.open(pfad)
        start_string = pfad[:pfad.index(".")]
        ende_string = pfad[pfad.index("."):]
        im_backup.save(start_string + "-original" + ende_string)

Currently I am working on a solution with os which could work, but I have the feeling it has to be simple. I red the documentation of PIL.Image.save, there are more arguments which can be passed in to save, but I dont figured out which one has to be used to prevent overriding.

My current solution (not working yet) is checking with os.listdir(directory) wether there is already a (start_string + "-original" + ende_string) file and only save it there if it is false.

Thanks in advance!

Answer 1

Consider using os.path.splitxext instead of slicing and indexing. You can also use os.path.isfile instead of listdir .

import os
pfad = askopenfilename()
name, ext = os.path.splitext(pfad)
backup_name = name + "-original" + ext
if not os.path.isfile(backup_name):
    im_backup = Image.open(pfad)
    im_backup.save(backup_name)

Answer 2

It's probably bot possible to do what you want by passing something to .save() .

The thing in the docs that probably made you think that it's possible is this:

• file – File name or file object.
• format – Optional format override. If omitted, the format to use is determined from the filename extension. If a file object was used instead of a filename, this parameter should always be used.
• options – Extra parameters to the image writer.

But in the source code there are lines,

self.encoderinfo = params
self.encoderconfig = ()

in which all the options are stored in a variable that has relation to encoder, so it's probably not what you want.

So, you should probably consider doing what @Kevin suggested.