FEATURE REQUEST: Use instance segmentation for particle detection

[alexhagen]

The particle detection could be automated (and user to user bias removed) with an instance segmentation algorithm instead of thresholding. Given enough time and images, i can implement and train that if it's desired. I can fork off and start if 1) you think it's a good idea, and 2) there are a lot of images (hopefully with their threshold settings noted) somewhere or someway to get them. What do you think?