An automated method for rapidly analyzing percentage of positive cells from immunostained tissue sections is disclosed. The method is an improved multi-stage dynamic thresholding series of steps applied to monochromatic gray-scale values of color channels of digital image of tissue. The method requires color digital images of tissue. The method discloses sequential stages to obtain a step-wise progression of preliminary image planes iteratively combined to obtain a final immunostained and non-immunostained images of cells of the same cell class. The final results are segmented cells that are digitally countable. The percent of immunostained cells over the total cells are calculated in tissue section. The cell characteristics, including cell size and its immunostaining intensity are captured and digitally stored per cell. The segmented single cell color image as well as the corresponding cell characteristic are displayed as a dot plot two-dimensional flow cytometry-like manner.