Apparatus for correcting an image for an artifact, the apparatus comprising: an input unit for receiving an initial image; a processing unit for processing the initial image to effect a correction; an output unit for outputting a corrected version of the initial image; the processing unit comprising: a correction sampler configured to forward the initial image to an artifact corrector and to receive therefrom a sample of a corrected image, the sample image being the result of a corrective action applied to the initial image by the artifact corrector; characterised in that a comparator configured to compare the initial image and the corrected sample image to so establish a corrector image representing the corrective action of the artifact corrector on the initial image; an artifact correction controller configured to adaptively re-apply the respective corrective action in a weighted manner to any one of a plurality of image points in the initial image, the weights used per image point for the weighting of the corrective action related to a degree to which image information in a neighbourhood around that image point is compensable by corresponding image information in a corresponding neighbourhood in the corrector image, the output unit configured to output the so adaptively re-corrected initial image as the corrected version of the initial image. a processing unit for processing the initial image to effect a correction; an output unit for outputting a corrected version of the initial image; the processing unit comprising: a correction sampler configured to forward the initial image to an artifact corrector and to receive therefrom a sample of a corrected image, the sample image being the result of a corrective action applied to the initial image by the artifact corrector; characterised in that a comparator configured to compare the initial image and the corrected sample image to so establish a corrector image representing the corrective action of the artifact corrector on the initial image; an artifact correction controller configured to adaptively re-apply the respective corrective action in a weighted manner to any one of a plurality of image points in the initial image, the weights used per image point for the weighting of the corrective action related to a degree to which image information in a neighbourhood around that image point is compensable by corresponding image information in a corresponding neighbourhood in the corrector image, the output unit configured to output the so adaptively re-corrected initial image as the corrected version of the initial image. a correction sampler configured to forward the initial image to an artifact corrector and to receive therefrom a sample of a corrected image, the sample image being the result of a corrective action applied to the initial image by the artifact corrector; characterised in that a comparator configured to compare the initial image and the corrected sample image to so establish a corrector image representing the corrective action of the artifact corrector on the initial image; an artifact correction controller configured to adaptively re-apply the respective corrective action in a weighted manner to any one of a plurality of image points in the initial image, the weights used per image point for the weighting of the corrective action related to a degree to which image information in a neighbourhood around that image point is compensable by corresponding image information in a corresponding neighbourhood in the corrector image, the output unit configured to output the so adaptively re-corrected initial image as the corrected version of the initial image.