A method for radiometric normalization of selected or target images relative to a base image of a geographical area, comprising determining normalization functions, and applying the normalization functions to the target images to normalize the target images relative to the base image; characterised by: automatically downsampling a first target image to produce a first low resolution target image, the first target image being a geospatial source image; automatically calculating image metadata for the first low resolution target image and first image metadata for a first portion of the base image which corresponds geographically to the first target image, wherein the metadata is image-related data that includes histogram data; automatically determining a first normalisation function based on a comparison of the image metadata for the first low resolution target image and the first image metadata for the base image; and applying the automatically-determined first normalisation function to the first target image to normalise the first target image relative to the base image; automatically downsampling a second target image to produce a second low resolution target image, the second target image being a geospatial source image; automatically calculating image metadata for the second low resolution target image and second image metadata for a second portion of the base image which corresponds geographically to the second target image, wherein the metadata is image-related data that includes histogram data; automatically determining a second normalisation function based on a comparison of the image metadata for the second low resolution target image and the second image metadata for the base image; and applying the automatically-determined second normalisation function to the second target image to normalise the second target image relative to the base image; wherein the base image is a geospatial base layer image which extends to a geographic area of interest and which is a manually colour-balanced image or is otherwise radiometrically normalised; and the first portion and the second portion of the base image are different portions of the geospatial base layer image that are geographically concurrent with the respective first and second target images. automatically downsampling a first target image to produce a first low resolution target image, the first target image being a geospatial source image; automatically calculating image metadata for the first low resolution target image and first image metadata for a first portion of the base image which corresponds geographically to the first target image, wherein the metadata is image-related data that includes histogram data; automatically determining a first normalisation function based on a comparison of the image metadata for the first low resolution target image and the first image metadata for the base image; and applying the automatically-determined first normalisation function to the first target image to normalise the first target image relative to the base image; automatically downsampling a second target image to produce a second low resolution target image, the second target image being a geospatial source image; automatically calculating image metadata for the second low resolution target image and second image metadata for a second portion of the base image which corresponds geographically to the second target image, wherein the metadata is image-related data that includes histogram data; automatically determining a second normalisation function based on a comparison of the image metadata for the second low resolution target image and the second image metadata for the base image; and applying the automatically-determined second normalisation function to the second target image to normalise the second target image relative to the base image; wherein the base image is a geospatial base layer image which extends to a geographic area of interest and which is a manually colour-balanced image or is otherwise radiometrically normalised; and the first portion and the second portion of the base image are different portions of the geospatial base layer image that are geographically concurrent with the respective first and second target images.