A display, comprising: an active matrix organic light emitting diode (AMOLED) panel having a plurality of pixels arranged in an array, each pixel comprising: (a) an organic light emitting diode (OLED) having a cathode electrically coupled to a first supply voltage, OVSS, a anode and an emissive layer formed between the cathode and the anode: (b) a driving circuit having: (i) a first transistor having a gate, a drain electrically coupled to a second supply voltage, OVDD, and a source electrically coupled to the anode of the OLED; (ii) a second transistor having a gate electrically coupled to a scan signal, Vscan, a drain electrode electrically coupled to the gate of the first transistor, and a source electrode electrically coupled to a data signal, Vdata; wherein the display further comprises a storage capacitor and a photosensor, characterized in that: (iii) the storage capacitor (Cst) is electrically connected between the gate and the drain of the first transistor; (c) the display further comprises a bias line for outputting a sensing signal, Vbias; and (d) the photo sensor is electrically coupled between the anode of the OLED and the bias line; wherein the sensing current of the photo sensor that is output from the bias line corresponds to the subtraction of the current from the drain to the source of the first transistor minus the current of the OLED. an active matrix organic light emitting diode (AMOLED) panel having a plurality of pixels arranged in an array, each pixel comprising: (a) an organic light emitting diode (OLED) having a cathode electrically coupled to a first supply voltage, OVSS, a anode and an emissive layer formed between the cathode and the anode: (b) a driving circuit having: (i) a first transistor having a gate, a drain electrically coupled to a second supply voltage, OVDD, and a source electrically coupled to the anode of the OLED; (ii) a second transistor having a gate electrically coupled to a scan signal, Vscan, a drain electrode electrically coupled to the gate of the first transistor, and a source electrode electrically coupled to a data signal, Vdata; wherein the display further comprises a storage capacitor and a photosensor, characterized in that: (iii) the storage capacitor (Cst) is electrically connected between the gate and the drain of the first transistor; (c) the display further comprises a bias line for outputting a sensing signal, Vbias; and (d) the photo sensor is electrically coupled between the anode of the OLED and the bias line; wherein the sensing current of the photo sensor that is output from the bias line corresponds to the subtraction of the current from the drain to the source of the first transistor minus the current of the OLED. (a) an organic light emitting diode (OLED) having a cathode electrically coupled to a first supply voltage, OVSS, a anode and an emissive layer formed between the cathode and the anode: (b) a driving circuit having: (i) a first transistor having a gate, a drain electrically coupled to a second supply voltage, OVDD, and a source electrically coupled to the anode of the OLED; (ii) a second transistor having a gate electrically coupled to a scan signal, Vscan, a drain electrode electrically coupled to the gate of the first transistor, and a source electrode electrically coupled to a data signal, Vdata; (i) a first transistor having a gate, a drain electrically coupled to a second supply voltage, OVDD, and a source electrically coupled to the anode of the OLED; (ii) a second transistor having a gate electrically coupled to a scan signal, Vscan, a drain electrode electrically coupled to the gate of the first transistor, and a source electrode electrically coupled to a data signal, Vdata; (iii) the storage capacitor (Cst) is electrically connected between the gate and the drain of the first transistor; (c) the display further comprises a bias line for outputting a sensing signal, Vbias; and (d) the photo sensor is electrically coupled between the anode of the OLED and the bias line; wherein the sensing current of the photo sensor that is output from the bias line corresponds to the subtraction of the current from the drain to the source of the first transistor minus the current of the OLED. (c) the display further comprises a bias line for outputting a sensing signal, Vbias; and (d) the photo sensor is electrically coupled between the anode of the OLED and the bias line; wherein the sensing current of the photo sensor that is output from the bias line corresponds to the subtraction of the current from the drain to the source of the first transistor minus the current of the OLED.