按照原比例缩小图片：
from PIL import Imageimport osdef scale_down(img_path, save_path, size, speed = 100, quality = 75):''':func: 按比例缩小图片:param img_path: 原图路径:param save_path: 保存路径:param size: 目的大小，以kb为单位:param speed: 缩小速度，过小时会引起震荡:param quality: 保存图像的质量，值的范围从1（最差）到95（最佳）;使用中应尽量避免高于95的值; 100会禁用部分JPEG压缩算法，并导致大文件图像质量几乎没有任何增益。在图像过分缩小的情况下可以将设置成比较大的quality值；'''img = Image.open(img_path)img.save(save_path, 'JPEG', quality = quality)while os.path.getsize(save_path) > size * 1024:# (width, heighth)width, height = img.size[0] - speed, img.size[1] - speedimg.thumbnail((width, height), Image.ANTIALIAS)img.save(save_path, 'JPEG', quality = quality)#print('width * height:', width, height, '\tszie:', os.path.getsize(save_path))print('It has finished.\nthe save_path: {0}\nthe final size: {1}kb\nwidth * height: {2} * {3}'.format(save_path, os.path.getsize(save_path)/1024, img.size[0], img.size[1]))if __name__ == '__main__':scale_down('./cns.jpg', './cns_.jpg', 190)
