So, the Johnson criteria is not sufficient to set up reliable, repeatable, specification table, as several factors influence the performance ranges: the field of view, the spatial resolution and thermal sensitivity of the infrared camera, the spectral band of detection, the shape and camouflage of the target, the experience of the operator …
In order to compare the performance of systems from different manufacturers, it is necessary to establish a common test frame, listing the conditions influencing the DRI range values. STANAG 4347 standards, developed by NATO, is widely adopted in the thermal imaging industry. This standard defines the target parameters (resulting from size, shape, temperature, material properties, emissivity…) and the conditions of use (resulting from ambient temperature, type of background scene…) to take into account in the MRTD (Minimum resolvable temperature difference) computation giving the values of the DRI ranges. See in the table below examples of target definition and the corresponding detection range of the SPYNEL-X, the IRST (Infrared Search&Track) with the best image quality and the longest detection range on the market: