A method for identifying biomarker-positive tumor cells is disclosed. The method includes, for example, reading a first digital image and a second digital image into memory, the first and second digital image depicting the same area of a first slide； identifying a plurality of nuclei and positional information of said nuclei by analyzing the light intensities in the first digital image； identifying cell membranes which comprise the biomarker by analyzing the light intensities in the second digital image and by analyzing the positional information of the identified nuclei； and identifying biomarker-positive tumor cells in said area, wherein a biomarker-positive tumor cell is a combination of one identified nucleus and one identified cell membrane that surrounds the identified nucleus.
