Established methods for sharpening details in images often lead to the magnification of background noise at the expense of detail clarity. This paper applies a method of image sharpening based on fuzzy morphology which is used to enhance historical images. The algorithm is a blend of morphological analysis and fuzzy reasoning, which unlike recognized methods of sharpening such as unsharp masking, does not excessively amplify noise. The algorithm is applied to the task of enhancing acuity in historical photographs, including colour slides.