np不支持存储内存，需转字节流进行存储，因此需要将np转base64以及bytes进行存储

图像np格式转base64:

```python
def image_to_base64(image_np):
 
        image = cv2.imencode('.jpg',image_np)[1].tostring()
        image_code = base64.b64encode(image)
        return image_code

图像np格式转bytes:

  def numpy_to_bytes(image_np):    

        data = cv2.imencode('.jpg', image_np)[1]
        image_bytes = data.tobytes()
        return image_bytes

同一张图片bytes长度小于base64：
ok 0
img_b64 <class 'bytes'>
426684
img_byt <class 'bytes'>
320011
-------------------------------
ok 1
img_b64 <class 'bytes'>
427368
img_byt <class 'bytes'>
320525