Resize image by maintaining aspect ratio with adding padding

resize-image-with-padding.py

import numpy as np
import PIL
from PIL import Image

def resize_image(np_img):
    """Resizes image with maintaining aspect ratio"""
    # Convert numpy array image into Pillow format image
    im = Image.fromarray(np_img)

    # Find max size of an image
    x, y = im.size
    max_size = max(x, y)

    # Draw black image and paste input image in middle
    new_im = Image.new('RGBA', (max_size, max_size), (0, 0, 0))
    new_im.paste(im, (int((max_size - x) / 2), int((max_size - y) / 2)))

    # Resize the image
    new_im = new_im.resize(
        (cfg.image_width, cfg.image_height), PIL.Image.ANTIALIAS)
    # np_resized_img = np.array(new_im)

    # Convert to RGB and drop alpha channel
    new_im = new_im.convert("RGB")
    np_resized_img = np.asarray(new_im, dtype=np.float32) / 255
    np_resized_img = np_resized_img[:, :, :3]
    np_resized_img = np.array(np_resized_img, dtype=np.int)

    return np_resized_img