by Lin Yangchen
Philatelic consensus favours scanning over photographing stamps, but scanners do not reproduce the surface texture of paper and print very well. This is because the scanner's light source is always directly above the stamp, turning it from a three-dimensional object to a two-dimensional one devoid of microtopography.
In a photograph, on the other hand, an oblique light source can be used to accentuate the surface contours, be they pits in the paper coating or the raised ink of a fine intaglio print. Indeed, the same principle is exploited by astronomers studying the lunar surface: craters of the moon are best discerned and analyzed when shadows are cast by oblique solar illumination.
Queen Wilhelmina of the Netherlands, 1930
Furthermore, scanners often suffer from noise, loss of colour depth and loss of dynamic range at high dpi settings, resulting in inaccurate reproduction of colour and detail even with calibration. Philatelic microscopes and close-up lens attachments have similar limitations, as well as spherical and chromatic aberration and loss of contrast through lens flare. Attempts to mitigate these shortcomings by boosting sharpness, contrast and saturation in software will create even more spurious detail that is not actually there.