ImageOps Official Documentation:
https://pillow.readthedocs.io/en/stable/reference/ImageOps.html

You can use ImageOps to quickly flip, mirror, and invert images.

Examples:

from PIL import Image, ImageOps

cat = Image.open('silly_cat.jpg')

cat_mir = ImageOps.mirror(cat)
cat_flip = ImageOps.flip(cat)
cat_inv = ImageOps.invert(cat)

cat_flip.save('cat_flip.jpg')
cat_inv.save('cat_inv.jpg')
cat_mir.save('cat_mir.jpg') 

Notice that ImageOps needs to be imported along with Image.

These functions return a new image, so avoid this error:

# Doesn't do anything (cat is unchanged)
ImageOps.mirror(cat)

# Does something (creates output object)
output = ImageOps.mirror(cat)

Original Image

Mirrored

Flipped

Inverted

ImageOps also has some other useful functions that you can check out in the documentation link at the top:

• Several handy resizing methods
• Add border (expand function)
• Crop a border
• Posterize (reduce color resolution)