This document specifies version 1.0 of the National Centre for Atmospheric Science Image Metadata Standard (NCAS-IMAGE). The standard relies on the capacity of digital image files to have metadata fields embedded within them. It has been designed to be analogous to the NCAS-GENERAL standard for netCDF data files, i.e. to ensure that all of the information required to interpret a data plot or a photograph is available within the file. The details covered by the standard include a description of what the image shows, the time and location for which it is applicable, who was responsible for creating it, when it was created, from where it is available, and the licence covering its use. This makes the image files compliant with FAIR data principles. Where possible, the NCAS-IMAGE standard has made use of metadata fields covered by existing standards, i.e. the Dublin Core Metadata Element Set (DCMES) and the International Press Telecommunications Council (IPTC) Photo Metadata Standard.