Python/PIL Resize all images in a folder

In case you want to keep the same aspect ratio of the image you can use this script.

from PIL import Image
import os, sys

path = "/path/images/"
dirs = os.listdir( path )
final_size = 244;

def resize_aspect_fit():
    for item in dirs:
         if item == '.DS_Store':
             continue
         if os.path.isfile(path+item):
             im = Image.open(path+item)
             f, e = os.path.splitext(path+item)
             size = im.size
             ratio = float(final_size) / max(size)
             new_image_size = tuple([int(x*ratio) for x in size])
             im = im.resize(new_image_size, Image.ANTIALIAS)
             new_im = Image.new("RGB", (final_size, final_size))
             new_im.paste(im, ((final_size-new_image_size[0])//2, (final_size-new_image_size[1])//2))
             new_im.save(f + 'resized.jpg', 'JPEG', quality=90)
resize_aspect_fit()

Expanding on the great solution of @Sanjar Stone

for including subfolders and also avoid DS warnings you can use the glob library:

from PIL import Image
import os, sys
import glob

root_dir = "/.../.../.../"


for filename in glob.iglob(root_dir + '**/*.jpg', recursive=True):
    print(filename)
    im = Image.open(filename)
    imResize = im.resize((28,28), Image.ANTIALIAS)
    imResize.save(filename , 'JPEG', quality=90)

John Ottenlips’s solution created pictures with black borders on top/bottom i think because he used

  Image.new("RGB", (final_size, final_size))

which creates a square new image with the final_size as dimension, even if the original picture was not a square.

This fixes the problem and, in my opinion, makes the solution a bit clearer:

from PIL import Image
import os

path = "C:/path/needs/to/end/with/a/"
resize_ratio = 0.5  # where 0.5 is half size, 2 is double size

def resize_aspect_fit():
    dirs = os.listdir(path)
    for item in dirs:
        if item == '.jpg':
            continue
        if os.path.isfile(path+item):
            image = Image.open(path+item)
            file_path, extension = os.path.splitext(path+item)

            new_image_height = int(image.size[0] / (1/resize_ratio))
            new_image_length = int(image.size[1] / (1/resize_ratio))

            image = image.resize((new_image_height, new_image_length), Image.ANTIALIAS)
            image.save(file_path + "_small" + extension, 'JPEG', quality=90)


resize_aspect_fit()

This code just worked for me to resize images..

from PIL import Image
import glob
import os

# new folder path (may need to alter for Windows OS)
# change path to your path
path = 'yourpath/Resized_Shapes' #the path where to save resized images
# create new folder
if not os.path.exists(path):
    os.makedirs(path)

# loop over existing images and resize
# change path to your path
for filename in glob.glob('your_path/*.jpg'): #path of raw images
    img = Image.open(filename).resize((306,306))
    # save resized images to new folder with existing filename
    img.save('{}{}{}'.format(path,'/',os.path.split(filename)[1]))

For those that are on Windows:

from PIL import Image
import glob

image_list = []
resized_images = []

for filename in glob.glob('YOURPATH\*.jpg'):
    print(filename)
    img = Image.open(filename)
    image_list.append(img)

for image in image_list:
    image = image.resize((224, 224))
    resized_images.append(image)

for (i, new) in enumerate(resized_images):
    new.save('{}{}{}'.format('YOURPATH\', i+1, '.jpg'))

Heavily borrowed the code from @Sanjar Stone. This code work well in Windows OS.
Can be used to bulky resize the images and assembly back to its corresponding subdirectory.

Original folder with it subdir:
..DATAORI-DIR
├─Apolo
├─Bailey
├─Bandit
├─Bella

New folder with its subdir:

..DATANEW-RESIZED-DIR
├─Apolo
├─Bailey
├─Bandit
├─Bella

Gist link: https://gist.github.com/justudin/2c1075cc4fd4424cb8ba703a2527958b

from PIL import Image
import glob
import os

# new folder path (may need to alter for Windows OS)
# change path to your path
ORI_PATH = '..DATAORI-DIR'
NEW_SIZE = 224
PATH = '..DATANEW-RESIZED-DIR' #the path where to save resized images

# create new folder
if not os.path.exists(PATH):
    os.makedirs(PATH)

# loop over existing images and resize
# change path to your path
for filename in glob.glob(ORI_PATH+'**/*.jpg'): #path of raw images with is subdirectory
    img = Image.open(filename).resize((NEW_SIZE,NEW_SIZE))
    
    # get the original location and find its subdir
    loc = os.path.split(filename)[0]
    subdir = loc.split('\')[1]
    
    # assembly with its full new directory
    fullnew_subdir = PATH+"/"+subdir
    name = os.path.split(filename)[1]
    
    # check if the subdir is already created or not
    if not os.path.exists(fullnew_subdir):
        os.makedirs(fullnew_subdir)
    
    # save resized images to new folder with existing filename
    img.save('{}{}{}'.format(fullnew_subdir,'/',name))

Expanded the answer of Andrei M. In order to only change the height of the picture and automatically size the width.

from PIL import Image
import os

path = "D:/.../.../.../resized/"
dirs = os.listdir(path)

def resize():
    for item in dirs:
        if item == '.jpg':
            continue
        if os.path.isfile(path+item):
            image = Image.open(path+item)
            file_path, extension = os.path.splitext(path+item)
            size = image.size

            new_image_height = 190
            new_image_width = int(size[1] / size[0] * new_image_height)

            image = image.resize((new_image_height, new_image_width), Image.ANTIALIAS)
            image.save(file_path + "_small" + extension, 'JPEG', quality=90)


resize()

If you want to resize any image from a folder where without images files, other files also exist, then you can try this:

from genericpath import isdir
from PIL import Image
import os, sys

path = "C://...//...//....//...//"
save_path = "C://...//..//...//...//"
images = os.listdir(path)

if not os.path.isdir(save_path):
    os.makedirs(save_path)


for image in images:
    image_path = os.path.join(path, image)
    iamge_save_path = os.path.join(save_path, image)
    if image.split(".")[1] not in ["jpg", "png"]:
        continue
    if os.path.exists(image_path):
        im = Image.open(image_path)
        image_resized = im.resize((224,224))
        image_resized.save(iamge_save_path, quality=90)
        # print("saved")

Safer to use pathlib

As jwal commented on a similar question, use the object-oriented counterparts for os of pathlib:

• p = Path('images') to define the path instance (here as directory relative to current)
• Path.iterdir() to find files in the path instance
• Path.absolute() to get the absolute-path for file-IO functions
• Path.joinpath(*other) to add subfolders or filenames
• Path.mkdir(parents=True, exist_ok=True)
• Path.name to return the basename of the file (like picture.png)

from pathlib import Path

# folder = 'images'
# new_dimension = (width, height)
def resize(folder, new_dimension, new_subdir):
    
    images_folder = Path(folder)
    for child in images_folder.iterdir():
        print("Found image:", child)
        image_path = child.absolute()

        image = Image.open(image_path)
        resized_image = image.resize()  # could also add Image.ANTIALIAS

        # create if the subdir not exists
        subdir = images_folder.join(new_subdir)
        if not subdir.exists():
            subdir.mkdir(parents=True, exist_ok=True)
        
        to_path = subdir.joinpath(child.name)  # join adds the path-separators
        print("Saving resized to:", to_path)
        resized_image.save(to_path)  # could also add save-options like 'JPEG', quality=90