The invention relates to a method and apparatus for detecting asymmetry in transient signals and to a method and apparatus for correcting such asymmetry. In the apparatus for detecting asymmetry there is provided a pre-shoot filter (1) for receiving an input signal Yin and asymmetrically filtering it utilizing a first set of filter coefficients to provide a first output in which substantially only pre-shoots of input transient signals are present, an after-shoot filter (2) for receiving the input signal and symmetrically filtering it utilizing a second set of filter coefficients to provide a second output in which substantially only after-shoots of input transient signals are present, and summing and comparison means (3 to 11) for summing the first outputs over a predetermined time interval, summing the second outputs over the predetermined time interval, and comparing first and second summed outputs to give an output signal indicating whether pre-shoots or after-shoots predominate over the predetermined time interval.