Thanks for your reply! If it's just a coincidence that every single one has a stalled blood vessel in it, then that's quite a coincidence. That's the case with every single one that I've seen. It's just hard to believe that two things that cooccur with such regularity could just be a coincidence, but I guess that could be the case. I'm not saying that one is causing the other, but there could be a third variable that somehow causing both of them. Although I guess that would be highly unlikely if the fuzzy line is just an artifact of the process.
I don't understand the whole concept of stitching the images together. What does that mean? Why does that need to be done? It just seems to make the whole issue of locating the target blood vessel that much more difficult. I think it would really be great if they could have some kind of graphic representation of just exactly what's going on here that would clarify the situation. I still don't understand what the stack is. What is being stacked? An overview of the whole process would really be helpful. I'm really having trouble visualizing what's going on.