1Diabetic Foot Clinic, King's College Hospital NHS Foundation Trust, Denmark Hill, London, SE5 9RS UK. 2Division of Diabetes and Nutritional Sciences, King's College London, London, UK. 3Temperature and Humidity, National Physical Laboratory, London, UK. 4Microvascular Diagnostics, Northern Medical Physics and Clinical Engineering, Newcastle upon Tyne Hospitals, Newcastle upon Tyne, UK. 5Community Podiatry Department, Pennine Acute Hospitals NHS Trust, Manchester, UK. Photometrix Imaging Ltd, Pontypridd, UK. 7Department of Computing, University of South Wales, Pontypridd, UK.