Imaging system for imaging an object and generating a measure of authenticity of the object, the imaging system comprising: one or more image sensors, the one or more image sensors being hereinafter referred to as "image sensor arrangement"; and one or more optical elements, the one or more optical elements being hereinafter referred to as "dispersive imaging arrangement", wherein the dispersive imaging arrangement is so that, when electromagnetic radiation from the object illuminates the dispersive imaging arrangement, at least part of the electromagnetic radiation splits out in different directions into at least a non-dispersed part and a dispersed part; and positioned relative to the image sensor arrangement in such a manner as to allow the image sensor arrangement to image said non-dispersed part in a first portion of the image sensor arrangement, and said dispersed part in a second portion of the image sensor arrangement, the imaging system being configured for, after the image sensor arrangement has, in at least one imaging period, imaged the non- dispersed part and the dispersed part, generating a measure of authenticity of the object depending at least on a relation between the imaged dispersed part, the imaged non-dispersed part, and reference spectral information, characterised in that the generating of the measure of authenticity comprises one of: deconvolving the imaged dispersed part by the imaged non-dispersed part, and determining the extent to which the result corresponds to the reference spectral information; deconvolving the imaged dispersed part by the reference spectral information, and determining the extent to which the result corresponds to the imaged non-dispersed part; and convolving the imaged non-dispersed part and the reference spectral information, and determining the extent to which the result corresponds to the imaged dispersed part. one or more image sensors, the one or more image sensors being hereinafter referred to as "image sensor arrangement"; and one or more optical elements, the one or more optical elements being hereinafter referred to as "dispersive imaging arrangement", wherein the dispersive imaging arrangement is so that, when electromagnetic radiation from the object illuminates the dispersive imaging arrangement, at least part of the electromagnetic radiation splits out in different directions into at least a non-dispersed part and a dispersed part; and positioned relative to the image sensor arrangement in such a manner as to allow the image sensor arrangement to image said non-dispersed part in a first portion of the image sensor arrangement, and said dispersed part in a second portion of the image sensor arrangement, so that, when electromagnetic radiation from the object illuminates the dispersive imaging arrangement, at least part of the electromagnetic radiation splits out in different directions into at least a non-dispersed part and a dispersed part; and positioned relative to the image sensor arrangement in such a manner as to allow the image sensor arrangement to image said non-dispersed part in a first portion of the image sensor arrangement, and said dispersed part in a second portion of the image sensor arrangement, deconvolving the imaged dispersed part by the imaged non-dispersed part, and determining the extent to which the result corresponds to the reference spectral information; deconvolving the imaged dispersed part by the reference spectral information, and determining the extent to which the result corresponds to the imaged non-dispersed part; and convolving the imaged non-dispersed part and the reference spectral information, and determining the extent to which the result corresponds to the imaged dispersed part.