We're going to use Image and ImageOps components of Pillow module to resize/crop image.

How to resize an image keeping aspect ratio

from PIL import Image, ImageOps

im = Image.open('/var/www/examples/heroine.png')
width = 100
height = width * im.size[1]/im.size[0]

im = im.resize((width, height))

• 100 - resized image width,
• width * im.size[1]/im.size[0] - calculates height so that aspect ratio is maintained.

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How to crop an image from center

im = Image.open('/var/www/examples/heroine.png')
crop = (400, 400)
left = round((im.size[0] - crop[0])/2)
top = round((im.size[1] - crop[1])/2)
im = im.crop((left, top, crop[0]+left, crop[1] + top))

• (400, 400) - cropping area width and height,
• (im.size[0] - crop[0])/2` - left coordinate of a crop area to position in the horizontal center,
• (im.size[1] - crop[1])/2` - top coordinate of a crop area to position in the vertical center.

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How to resize/crop an image cropped to fit certain area (cover thumbnail)

im = Image.open('/var/www/examples/heroine.png')
im = ImageOps.fit(im, (100,100), Image.ANTIALIAS)

• 100,100 - thumbnail area width and height,
• ImageOps.fit( - fits an image into given area.

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