1. An image-processing method comprising the steps of: (i) obtaining an image including a target object, the image being formed by an array of pixels; (ii) extracting a frame portion from the image, the frame portion being at least a portion of the pixels forming the image, corresponding to a region of interest in the image, the region of interest comprising the target object and the frame portion having an associated phase, representative of a sub-pixel translation shift of the region of interest defined by the frame portion relative to the region of interest defined by another frame portion; (iii) storing the frame portion in the stack, the storing including discarding an oldest previously stored frame portion from the stack if the number of frame portions stored in the stack has reached the predetermined number; (iv) repeating steps (i) to (iii) a plurality of times; and (v) calculating a super-resolved image from a plurality of phase averages, wherein each phase average is the average of frame portions in the stack having the same phase, wherein the frame portions of each phase average have an associated phase representative of a sub-pixel translation shift of the regions of interest defined by those frame portions relative to the region of interest defined by another frame portion.