How can I change the blobs from rectangles to spheres and change the text ID to different textures?

Hi, I have a question to the youtube tutorial 11.9: Computer Vision: Blob Tracking with Persistence - Processing Tutorial. I would like to have three spheres with three different texture to track three objects of one color for a performance. How can I change the blobs from rectangles to spheres and change the text ID to different textures? I'm new to coding in processing.