python使用Pillow/Opencv对图片进行等比缩放

心已赠人 2022-09-06 00:08 314阅读 0赞

"""
    1. 图片的等比缩放;（m,n） <- (scale_size, scale_size)
    2. 缩放后的图片放置在中间区域，其它区域像素填0；
    """
    
    import cv2
    from PIL import Image
    import numpy as np
    
    
    class UniformScale:
        def __init__(self, img_file, scale_size):
            """
            :param img_file: 图片文件
            :param scale_size: 对照片进行缩放的尺寸 （scale_size, scale_size）
            """
            self.img_file = img_file
            self.scale_size = scale_size
    
        def pil_scale(self):
            img = Image.open(self.img_file).convert('RGB')
            h = img.height
            w = img.width
    
            ratio = min(self.scale_size / h, self.scale_size / w)
            new = img.resize((int(w * ratio), int(h * ratio)))
            new = np.asarray(new, np.uint8)
    
            img_pad = np.zeros((self.scale_size, self.scale_size, 3))
            dw = int((self.scale_size - int(w * ratio)) / 2)
            dh = int((self.scale_size - int(h * ratio)) / 2)
            img_pad[dh: int(h * ratio) + dh, dw: int(w * ratio) + dw, :] = new
    
            img_pad = Image.fromarray(np.uint8(img_pad))
            img_pad.save('test_PIL.jpg')
    
            return img_pad
    
        def cv2_scale(self):
            img = cv2.imread(self.img_file)
            h, w = img.shape[:2]
            ratio = min(self.scale_size / h, self.scale_size / w)
            new = cv2.resize(img, (int(w * ratio), int(h * ratio)), interpolation=cv2.INTER_CUBIC)
    
            img_pad = np.full((self.scale_size, self.scale_size, 3), 0, np.uint8)
            dw = int((self.scale_size - int(w * ratio)) / 2)
            dh = int((self.scale_size - int(h * ratio)) / 2)
            img_pad[dh: int(h * ratio) + dh, dw: int(w * ratio) + dw, :] = new
    
            cv2.imwrite('test_cv2.jpg', img_pad)
    
            return img_pad
    
    
    if __name__ == '__main__':
        UniformScale(img_file='ok.jpeg', scale_size=256).pil_scale()