A computer-implemented method for sampling images generated by automated imaging equipment, the method comprising: receiving a first image set generated by the automated imaging equipment during a first inspection period; storing an image library in a memory, the image library initially consisting of the first image set; sequentially receiving a plurality of subsequent image sets generated by the automated imaging equipment during a plurality of subsequent inspection periods; and updating the image library stored in the memory, characterised in that updating the image library stored in the memory includes, for each subsequent image set, adding to the image library j images distributed among the subsequent image set and removing from the image library j images distributed among a current instance of the image library, j being an integer greater than zero, for each successive image set in the plurality of subsequent image sets, j decreases, and updating the image library stored in the memory includes, for each subsequent image set, either: removing from the image library every n th image in the current instance of the image library; or adding to the image library every n th subset of Y images in the subsequent image set and removing from the image library every n th subset of Y images in the current instance of the image library, n being the number of the inspection period during which the subsequent image set was generated and Y being an integer greater than one. receiving a first image set generated by the automated imaging equipment during a first inspection period; storing an image library in a memory, the image library initially consisting of the first image set; sequentially receiving a plurality of subsequent image sets generated by the automated imaging equipment during a plurality of subsequent inspection periods; and updating the image library stored in the memory, characterised in that updating the image library stored in the memory includes, for each subsequent image set, adding to the image library j images distributed among the subsequent image set and removing from the image library j images distributed among a current instance of the image library, j being an integer greater than zero, for each successive image set in the plurality of subsequent image sets, j decreases, and updating the image library stored in the memory includes, for each subsequent image set, either: removing from the image library every n th image in the current instance of the image library; or adding to the image library every n th subset of Y images in the subsequent image set and removing from the image library every n th subset of Y images in the current instance of the image library, n being the number of the inspection period during which the subsequent image set was generated and Y being an integer greater than one. updating the image library stored in the memory includes, for each subsequent image set, adding to the image library j images distributed among the subsequent image set and removing from the image library j images distributed among a current instance of the image library, j being an integer greater than zero, for each successive image set in the plurality of subsequent image sets, j decreases, and updating the image library stored in the memory includes, for each subsequent image set, either: removing from the image library every n th image in the current instance of the image library; or adding to the image library every n th subset of Y images in the subsequent image set and removing from the image library every n th subset of Y images in the current instance of the image library, n being the number of the inspection period during which the subsequent image set was generated and Y being an integer greater than one. removing from the image library every n th image in the current instance of the image library; or adding to the image library every n th subset of Y images in the subsequent image set and removing from the image library every n th subset of Y images in the current instance of the image library,