A drive circuit for a bi-stable display comprises: a driver (101, 102) which supplies drive waveforms (DWk) to the pixels (Pij) of the display during an image update period (IUk) wherein the image presented by the pixels (Pij) is updated. A controller (103) controls the driver (101, 102) to supply, during the image update period (IUk) wherein a particular optical transition of a particular one of the pixels (Pij) is required, an associated one of the drive waveforms (DWk) to the particular one of the pixels (Pij). The associated one of the drive waveforms (DWk) comprises a sequence of a particular number of pulse, (SPk), wherein consecutive ones of the pulses (SPk) of the sequence are separated by a separation period of time (SPT). The particular number of said pulses (SPk), and/or a duration of said pulses (SPk), and/or a duration of the separation period (SPT) of the associated one of the drive waveforms (DWk) is determined to obtain the particular optical transition at a desired energy of the associated one of the drive waveforms (DWk) to decrease an average value of the associated one of the drive waveforms (DWk).