PIL 彩色图像等比例缩放边缘补零

 

import numpy as np
from PIL import Image
from matplotlib import pyplot as plt


def img_pad(pil_file, fixed_size=300):
    w, h = pil_file.size

    if h >= w:
        factor = h / float(fixed_size)
        new_w = int(w / factor)
        if new_w % 2 != 0:
            new_w -= 1
        pil_file = pil_file.resize((new_w, fixed_size))
        pad_w = int((fixed_size - new_w) / 2)
        array_file = np.array(pil_file)
        array_file = np.pad(array_file, ((0, 0), (pad_w, pad_w), (0, 0)), 'constant')
    else:
        factor = w / float(fixed_size)
        new_h = int(h / factor)
        if new_h % 2 != 0:
            new_h -= 1
        pil_file = pil_file.resize((fixed_size, new_h))
        pad_h = int((fixed_size - new_h) / 2)
        array_file = np.array(pil_file)
        array_file = np.pad(array_file, ((pad_h, pad_h), (0, 0), (0, 0)), 'constant')

    output_file = Image.fromarray(array_file)
    return output_file


if __name__ == '__main__':
    img_path = r'.\1402.jpeg'
    img0 = Image.open(img_path)
    img1 = img_pad(img0)

    axs = plt.figure().subplots(1, 2)
    axs[0].imshow(img0)
    axs[0].set_title('src')
    axs[0].axis('off')

    axs[1].imshow(img1)
    axs[1].set_title('pad')
    axs[1].axis('off')

    plt.show()

效果：