Background estimation and cell detection. (a) The proposed cell model: (i) Coarsely cropped well in which well boundaries are visible. (ii) Applying the cell model to (i). In contrast with the perfect result obtained by applying the cell model to a cropped well interior with no boundaries, here the cell model performs very poorly where the cropped well contains visible well boundaries. (iii) Corrected well image after point-wise background subtraction. (iv) Applying the cell model to (iii). (b) The process of the proposed cell model and background estimation method: (i) Point-wise estimated background (). (ii) Subtracting out the estimated background image obtained in (i) from the original image. (iii) Located cell centers applying cell model P in (8).