Fear Filter is a digital artwork comprising of a mobile phone photo filters application for Android / iOS platforms and a digital photo stream. The photo filters are created by gathering current and historical information about the UK Threat Level from a live feed from MI5, the UK security service. Photographs taken with the mobile application are transformed by the photo filters, each of which correspond to a different moment in time and the related Threat Level from that period. The filters cover the period 1 August 2006 until the present moment. Photos shared from the mobile application are automatically posted to a public photo stream. The artwork draws together the ubiquity of photography as a networked medium and the growing use of photo filters apps with the invisible ubiquity of the UK Threat Level. Utilising pattern recognition and algorithmic image analysis each photo filter visualises the UK Threat Level by colourising and redacting the subject of the photograph according to the severity of the Terror Threat Level. Fear Filter exploits the confluence of mobile digital photography, platforms, networks and the online security theatre of the UK Threat Level to reformulate the relationship between photography and terrorism.