问将矩形图像调整为正方形，保持比率，并以黑色填充背景

EN

from PIL import Image

def make_square(im, min_size=256, fill_color=(0, 0, 0, 0)):
    x, y = im.size
    size = max(min_size, x, y)
    new_im = Image.new('RGBA', (size, size), fill_color)
    new_im.paste(im, (int((size - x) / 2), int((size - y) / 2)))
    return new_im

test_image = Image.open('hLarp.png')
new_image = make_square(test_image)
new_image.show()

new_image = make_square(test_image, fill_color=(255, 255, 255, 0))

#Importing modules opencv + numpy
import cv2
import numpy as np

#Reading an image (you can use PNG or JPG)
img = cv2.imread("image.png")

#Getting the bigger side of the image
s = max(img.shape[0:2])

#Creating a dark square with NUMPY  
f = np.zeros((s,s,3),np.uint8)

#Getting the centering position
ax,ay = (s - img.shape[1])//2,(s - img.shape[0])//2

#Pasting the 'image' in a centering position
f[ay:img.shape[0]+ay,ax:ax+img.shape[1]] = img

#Showing results (just in case) 
cv2.imshow("IMG",f)
#A pause, waiting for any press in keyboard
cv2.waitKey(0)

#Saving the image
cv2.imwrite("img2square.png",f)
cv2.destroyAllWindows()

from PIL import Image

def black_background_thumbnail(path_to_image, thumbnail_size=(200,200)):
    background = Image.new('RGBA', thumbnail_size, "black")    
    source_image = Image.open(path_to_image).convert("RGBA")
    source_image.thumbnail(thumbnail_size)
    (w, h) = source_image.size
    background.paste(source_image, ((thumbnail_size[0] - w) / 2, (thumbnail_size[1] - h) / 2 ))
    return background

if __name__ == '__main__':
    img = black_background_thumbnail('hLARP.png')
    img.save('tmp.jpg')
    img.show()