Digitizing a porcelain card – in pursuit of a faithful reproduction

porseleinkaart_mo_03

The KU Leuven University Archives requested a digital reproduction of a porcelain card. A porcelain card is a 19th century lithographic printing technique that uses either white lead or kaolin to produce prints with a very distinct shimmer (more information here). Because this shimmer is an essential aspect of the porcelain card, we somehow had to preserve some of the shine in our reproduction. Since common digitization techniques are obviously tailored to minimize the amount of reflection, this turned out to be quite a challenge.

Our first capture conforms to the Metamorfoze guidelines and therefore has accurate contrast and good colour fidelity. Unfortunately, the reflective surface characteristics have been lost during the reproduction. Especially the gold pigment is much darker and duller than in the actual print.

Porseleinkaart_MO_01

Conventional lighting setup with strobes on the left and right of the object, at a 45° angle.

HyperFocal: 0

First capture with conventional setup. Good contrast and colour but no reflection and the gold pigment looks very flat.

In a second attempt we repositioned the lights to create quite a bit of reflection on the porcelain card. The gold pigment in the resulting image looks much more lively and the white background also lights up a little more. Sadly, the reflections have caused the contrast and colour saturation to be washed out.

Porseleinkaart_MO_02

Alternative lighting setup to create reflection.

HyperFocal: 0

Nice reflections on the gold pigment, but contrast and colour saturation appear washed out.

Our third and final attempt takes place in the digital realm. Confronted with the physical limitations of light and reflection, we decided to combine the best elements of both captures in a final version.

3 samen

Left: first capture, center: second capture, right: first and second capture combined

HyperFocal: 0

Final image.

While a good reproduction starts with Metamorfoze conformity, digitizing the porcelain card clearly showed that sometimes we have to take our images just that little bit further to achieve a faithful reproduction of the characteristics of the original.

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