This process, as coded, would normally show a black screen, with an overlay of a circle.
I would suggest that you define 3 IMAQ memory spaces outside the loop.
1. The first one would hold the streaming images from the camera.
2. the second should hold a fixed copy of one image.
3. The third would be your working memory area. (similar to the random one you now show)
4 . In the loop, copy the latest image from the camera to the fixed memory and also the working memory.
5 After processing, put the overlay onto the fixed image.
By trying to store everything in one memory space, you are sometimes displaying streamed camera images and sometimes processing images.
Hope this helps.
Jerry