AttributeError when trying to reinsert modified images into ROS2 bag file with Python

Question

I'm currently working with ROS2 and Python to process image data stored in a ROS2 bag file. My task involves extracting images from the bag, performing modifications, and then reinserting them. I am using the rosbags.rosbag2 library to interact with the ROS2 bag files and cv_bridge to convert ROS2 images to OpenCV format (and vice versa).

Here is the specific part of my environment and task setup:

• Operating System: Ubuntu 22.04
• Programming Language: Python 3.10.12

However, I've encountered an AttributeError when attempting to serialize the modified image back into the ROS2 message format. Here is the relevant portion of my code:

from cv_bridge import CvBridge
from rosbags.rosbag2 import Reader, Writer
from rosbags.typesys import Stores, get_typestore

bridge = CvBridge()
typestore = get_typestore(Stores.LATEST)
Image = typestore.types["sensor_msgs/msg/Image"]

with Reader(INPUT_BAGFILE) as reader, Writer(OUTPUT_BAGFILE) as writer:
    writer_connection = writer.add_connection("/d435i/color/image_raw", 
                                              "sensor_msgs/msg/Image", 
                                              typestore=typestore)
    
    for connection, timestamp, rawdata in reader.messages():
        if connection.topic == "/d435i/color/image_raw":
            msg = typestore.deserialize_cdr(rawdata, connection.msgtype)
            img = bridge.imgmsg_to_cv2(msg, desired_encoding="rgb8")

            # modify image here

            bridged_image = bridge.cv2_to_imgmsg(img, encoding="rgb8")
            image_message = Image(
                bridged_image.header,
                bridged_image.height,
                bridged_image.width,
                bridged_image.encoding,
                bridged_image.is_bigendian,
                bridged_image.step,
                bridged_image.data
            )

            new_msg = typestore.serialize_cdr(image_message, "sensor_msgs/msg/Image")
            writer.write(writer_connection, timestamp, new_msg)

In this case, the OUPUT_BAGFILE is a copy of the INPUT_BAGFILE. The error I receive is:

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Input In [13], in <cell line: 4>()
     13 bridged_image = bridge.cv2_to_imgmsg(img, encoding="rgb8")
     14 image_message = Image(
     15     bridged_image.header,
     16     bridged_image.height,
   (...)
     21     bridged_image.data
     22 )
---> 24 new_msg = typestore.serialize_cdr(image_message, 'sensor_msgs/msg/Image')
     25 writer.write(writer_connection, timestamp, new_msg)

File ~/.local/lib/python3.10/site-packages/rosbags/typesys/store.py:166, in Typestore.serialize_cdr(self, message, typename, little_endian)
    162 pack_into('BB', rawdata, 0, 0, little_endian)
    164 func = msgdef.serialize_cdr_le if little_endian else msgdef.serialize_cdr_be
--> 166 pos = func(rawdata[4:], 0, message, self)
    167 assert pos + 4 == size
    168 return rawdata.toreadonly()

File <string>:20, in serialize_cdr(rawdata, pos, message, typestore)

File <string>:20, in serialize_cdr(rawdata, pos, message, typestore)

File <string>:18, in serialize_cdr(rawdata, pos, message, typestore)

AttributeError: 'Time' object has no attribute 'sec'

I appreciate any insights or suggestions on how to resolve this error.