How to sync images captured with different frequecies through timestamps

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Hi,

I recently recorded some images with a RGB camera (operating with at 20 Hz) and a Lider (10 Hz). Now I would like to align those two images. However, they are not synchronized due to the different frequencies. Apparently, one could try to synchronize them my manipulating the timestamps like described here: http://wiki.ros.org/message_filters#T.... However, I don't quite understand what does the synchronizer actually do.

Could someone please tell me whether it's the correct the direction and how I should proceed?

The info of my bag reads as the following:

xxx@ubuntu:~$ rosbag info /home/xxx/Desktop/2019-06-18-11-38-00.bag 
path:        /home/xxx/Desktop/2019-06-18-11-38-00.bag
version:     2.0
duration:    40.6s
start:       Jun 18 2019 11:38:00.89 (1560850680.89)
end:         Jun 18 2019 11:38:41.49 (1560850721.49)
size:        3.2 GB
messages:    46042
compression: none [2072/2072 chunks]
types:       ouster_ros/PacketMsg    [4f7b5949e76f86d01e96b0e33ba9b5e3]
             sensor_msgs/Image       [060021388200f6f0f447d0fcd9c64743]
             sensor_msgs/Imu         [6a62c6daae103f4ff57a132d6f95cec2]
             sensor_msgs/PointCloud2 [1158d486dd51d683ce2f1be655c3c181]
topics:      /VIS/cam0/image_raw      812 msgs    : sensor_msgs/Image      
             /VIS/cam1/image_raw      812 msgs    : sensor_msgs/Image      
             /VIS/cam2/image_raw      813 msgs    : sensor_msgs/Image      
             /VIS/imu                7904 msgs    : sensor_msgs/Imu        
             /img_node/intensity_image     406 msgs    : sensor_msgs/Image      
             /img_node/noise_image         405 msgs    : sensor_msgs/Image      
             /img_node/range_image         406 msgs    : sensor_msgs/Image      
             /os1_cloud_node/imu          4057 msgs    : sensor_msgs/Imu        
             /os1_cloud_node/points        405 msgs    : sensor_msgs/PointCloud2
             /os1_node/imu_packets        4055 msgs    : ouster_ros/PacketMsg   
             /os1_node/lidar_packets     25967 msgs    : ouster_ros/PacketMsg

Thanks in advance!