This custom feature calculates the number of spots in each cell and is based on an analysis setup for an image with cells (DAPI) and spots (EGFP). The class tree could look like this:

To create this custom feature you have to define the following operand and expression for the class Cell:

• Operand a:
• Class: All Spots per Cell
• Feature: Count
• Define Custom Expression: a

The subsequent run of the analysis setting will add your custom feature as another column to the analysis table for the class Cell.