How can I segment cells from an image taken on a microscope, along the lines of what was done here in Matlab?
http://blogs.mathworks.com/steve/2006/06/02/cell-segmentation/
Also, if I take multiple image in different fluorescent channels (after staining the cells with some antibody/maker), how can I automatically quantitate the fraction of cells positive for each marker? Has anyone done something like this in Python? Or is there a library in Python that can be used to do this?
Have you read the tutorial on pythonvision.org?
http://pythonvision.org/basic-tutorial
It is very similar to what you are looking for.