Is there a way to know how many images rviz2 exactly has received?

[storrrrrrrrm]

when i am testing roi_cluster_fusion on the real car. i met a really strange problem. in rviz2,i oberserve topic /perception/object_recognition/detection/clustering/output/image_raw0,the image shows in very low frequency,and if i use cmd ros2 topic hz /perception/object_recognition/detection/clustering/output/image_raw0,it shows a low frequency,like 1 or 0.5 hz.

BUT,when i add some debug code,mainly to observe the timestamp,it shows like this:

[roi_cluster_fusion_node-6] current time:Sun Apr 24 14:31:28 2022
[roi_cluster_fusion_node-6] ,elapsed_seconds:0.102874
[roi_cluster_fusion_node-6] 14:31:28.369 check camera
[roi_cluster_fusion_node-6] 14:31:28.370 build cluster roi end
[roi_cluster_fusion_node-6] 14:31:28.370 calc iou
[roi_cluster_fusion_node-6] 14:31:28.370 prepare pub image msg
[roi_cluster_fusion_node-6] 14:31:28.370 end pub image msg
[roi_cluster_fusion_node-6] 14:31:28.370 prepare pub output msg
[roi_cluster_fusion_node-6] 14:31:28.370 end pub output msg
[roi_cluster_fusion_node-6] current time:Sun Apr 24 14:31:28 2022
[roi_cluster_fusion_node-6] ,elapsed_seconds:0.101066
[roi_cluster_fusion_node-6] 14:31:28.470 check camera
[roi_cluster_fusion_node-6] 14:31:28.471 build cluster roi end
[roi_cluster_fusion_node-6] 14:31:28.471 calc iou
[roi_cluster_fusion_node-6] 14:31:28.471 prepare pub image msg
[roi_cluster_fusion_node-6] 14:31:28.471 end pub image msg
[roi_cluster_fusion_node-6] 14:31:28.471 prepare pub output msg
[roi_cluster_fusion_node-6] 14:31:28.471 end pub output msg
[roi_cluster_fusion_node-6] current time:Sun Apr 24 14:31:28 2022
[roi_cluster_fusion_node-6] ,elapsed_seconds:0.0997986
[roi_cluster_fusion_node-6] 14:31:28.570 check camera
[roi_cluster_fusion_node-6] 14:31:28.571 build cluster roi end
[roi_cluster_fusion_node-6] 14:31:28.571 calc iou
[roi_cluster_fusion_node-6] 14:31:28.571 prepare pub image msg
[roi_cluster_fusion_node-6] 14:31:28.571 end pub image msg
[roi_cluster_fusion_node-6] 14:31:28.571 prepare pub output msg
[roi_cluster_fusion_node-6] 14:31:28.571 end pub output msg
[roi_cluster_fusion_node-6] current time:Sun Apr 24 14:31:29 2022
[roi_cluster_fusion_node-6] ,elapsed_seconds:0.508791

elapsed_seconds shows duration time bwtween ' RoiClusterFusionNodelet::fusionCallback' fuction call.
Here is the first problem: it does not enter into ' RoiClusterFusionNodelet::fusionCallback' every 0.1 s(liadr topic hz is 10,image topic hz is 20,i do not mean is should be 0.1s exactly,but as far as i understand,it should not be too far away from 0.1).

the second problem is : i play a bag of 10s length,and save the above output to log,count how many times end pub output msg occurs,it is random(i think this is connected with problem 1),but even if it occurs like 60 times or more, it means that it does publish the image 60 times，i keep my eyes watching image of /perception/object_recognition/detection/clustering/output/image_raw0 on rviz,it still shows with a very low frequency, and if i count how many frames i have seen, i would be just 9 or 10.

so,what i am sure now is that: roi_cluster_fusion do publish /perception/object_recognition/detection/clustering/output/image_raw0 for 60times.

my question is: rviz2 has recieved image of /perception/object_recognition/detection/clustering/output/image_raw0 for 60 times，but just show 9 of them or rviz2 just receive 9 images?

[Sharrrrk]

I would suggest you to have a look at the status/topic value under the specific topic you are concerning, just like the example below:

[storrrrrrrrm]

I would suggest you to have a look at the status/topic value under the specific topic you are concerning, just like the example below:

thanks, i finally found the problem of 'roi_cluster_fusion', it has nothing to do with rviz2 receiving images. As you mentioned,
status/topic value shows the number rviz2 actually receives