The limits of resolution

This paper challenges the notion that a fixed spatial resolution is applicable for digitising all items in a collection, irrespective of their characteristics. The fineness of detail in crafted objects depends on the granularity of the substrate, the diameter of the tool, and the visual contrast sensitivity of the craftsman. The ability of an imaging device to capture fine detail is characterised by its modulation transfer function (MTF). A technique based on the 1-D Fourier transform is introduced for determining the spatial frequency of the finest detail in an object. It is proposed that for capturing hand-crafted detail the image should resolve features of 50 μm diameter, requiring 40 samples per mm (1200 dpi).