A device for base calling is provided. The device includes a receptacle configured to hold a biosensor having a sample surface holding a plurality of clusters during a sequence of sampling events, an array of sensors sensing information from clusters disposed in corresponding pixel areas of the sample surface during the sampling events and generate sequences of pixel signals and a communication port configured to output the sequences of pixel signals. The device also includes a signal processor coupled to the communication port and configured to receive and process at least one pixel signal in the sequences of pixel signals that mixes light gathered from at least two clusters in a corresponding pixel area, and to base call each of the at least two clusters using the at least one pixel signal.