How to reduce the image file size using PIL
compression, image, python, python-imaging-library
Solution
A built-in parameter for saving JPEGs and PNGs is `optimize`.
from PIL import Image
foo = Image.open('path/to/image.jpg') # My image is a 200x374 jpeg that is 102kb large
foo.size # (200, 374)
# downsize the image with an ANTIALIAS filter (gives the highest quality)
foo = foo.resize((160,300),Image.ANTIALIAS)
foo.save('path/to/save/image_scaled.jpg', quality=95) # The saved downsized image size is 24.8kb
foo.save('path/to/save/image_scaled_opt.jpg', optimize=True, quality=95) # The saved downsized image size is 22.9kb
The `optimize` flag will do an extra pass on the image to find a way to reduce its size as much as possible. 1.9kb might not seem like much, but over hundreds/thousands of pictures, it can add up.
Now to try and get it down to 5kb to 10 kb, you can change the quality value in the save options. Using a quality of 85 instead of 95 in this case would yield: Unoptimized: 15.1kb Optimized : 14.3kb Using a quality of 75 (default if argument is left out) would yield: Unoptimized: 11.8kb Optimized : 11.2kb
I prefer quality 85 with optimize because the quality isn't affected much, and the file size is much smaller.
Problem
I am using PIL to resize the images there by converting larger images to smaller ones. Are there any standard ways to reduce the file size of the image without losing the quality too much? Let's say the original size of the image is 100 kB. I want to get it down to like 5 or 10 kB, especially for PNG and JPEG formats.