Disclosed are a touch sensitive display and a method of operation thereof. The display comprises a sensor having an input put array of electrodes and, capacitively coupled thereto, an output array of electrodes and a controller operable to perform a scan operation at every intersection point of said input array. The scan operation comprises measuring a touch value for an intersection point; determining a proportional difference between said touch value and a base touch value for said intersection point as a proportion of said base touch value, wherein said base touch value is indicative of there being no touch event on the sensor; and comparing the proportional difference to a predetermined proportional touch threshold so as to determine whether there is a touch event at that point.