A head-worn device , comprising: a camera configured to generate first pixel data from a field of view of the head-worn device; a display device to display second pixel data to a wearer of the head-worn device based on the first pixel data captured by the camera; weld detection circuitry configured to: determine whether a welding arc is present; and generate a control signal indicating a result of the determination; and pixel data processing circuitry configured to process the first pixel data captured by the camera to generate the second pixel data for display on the display device , wherein a mode of operation of said pixel data processing circuitry is selected from a plurality of modes based on said control signal; characterised in that : the head-worn device further comprises a receiver circuit configured to receive a communication to indicate whether a weld current is flowing through a weld torch ; the weld detection circuitry is configured to receive a signal representative of the weld current flowing through the weld torch ; and the weld detection circuitry is configured to determine whether a welding arc is present based on the communication received from the receiver circuit . a camera configured to generate first pixel data from a field of view of the head-worn device; a display device to display second pixel data to a wearer of the head-worn device based on the first pixel data captured by the camera; weld detection circuitry configured to: determine whether a welding arc is present; and generate a control signal indicating a result of the determination; and pixel data processing circuitry configured to process the first pixel data captured by the camera to generate the second pixel data for display on the display device , wherein a mode of operation of said pixel data processing circuitry is selected from a plurality of modes based on said control signal; characterised in that : the head-worn device further comprises a receiver circuit configured to receive a communication to indicate whether a weld current is flowing through a weld torch ; the weld detection circuitry is configured to receive a signal representative of the weld current flowing through the weld torch ; and the weld detection circuitry is configured to determine whether a welding arc is present based on the communication received from the receiver circuit . determine whether a welding arc is present; and generate a control signal indicating a result of the determination; and pixel data processing circuitry configured to process the first pixel data captured by the camera to generate the second pixel data for display on the display device , wherein a mode of operation of said pixel data processing circuitry is selected from a plurality of modes based on said control signal; characterised in that : the head-worn device further comprises a receiver circuit configured to receive a communication to indicate whether a weld current is flowing through a weld torch ; the weld detection circuitry is configured to receive a signal representative of the weld current flowing through the weld torch ; and the weld detection circuitry is configured to determine whether a welding arc is present based on the communication received from the receiver circuit . the head-worn device further comprises a receiver circuit configured to receive a communication to indicate whether a weld current is flowing through a weld torch ; the weld detection circuitry is configured to receive a signal representative of the weld current flowing through the weld torch ; and the weld detection circuitry is configured to determine whether a welding arc is present based on the communication received from the receiver circuit . <EOS>