Page 185 - Ming_China_Courts_and_Contacts_1400_1450 Craig lunas

Plate 19.6 VP SEM image of bamboo leaf cells from Ming dynasty Plate 19.7 VP SEM image of Morus australis (Chinese mulberry)
paper money. British Museum, London, CIB,EA 264 fibres from Ming dynasty paper money. British Museum, London CIB.
EA.260
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mulberry (Pl. 19.7). This appears to make the Ming paper representations of colour in analog and digital applications.
money comparable in composition to other types of early It is typically specified by three parameters (but can be
Chinese paper. 11 more), and it is the relationships between these parameters
Further research is needed to establish whether Ming which characterises a particular colour space. While
paper money was made of recycled materials, which might separating an RGB image down into its individual
explain why there is a range of plant types in apparently components can be useful, more information can be
different condition, possibly reflecting different production retrieved from digital images by converting into other colour
intensity. Although tiny samples were taken from the Ming spaces and examining those components. Mathematical
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notes studied recently, given that the Hitachi S-3700N VP algorithms enable the parameters of one colour space to be
SEM has a large chamber that can accommodate a transformed into another. These transformations are helpful
specimen size up to 300mm in diameter (and 110mm in for making colour descriptions more intuitive such as by
height at an analytical working distance of 10mm), in the describing colours in terms of their hue, saturation and
future it is possible that fragments of Ming paper money luminance.
from other collections that do not exceed these dimensions Cultural heritage material is often composed of several
could be put directly into the VP SEM chamber for very different types of inks and pigments overlying a substrate
carefully monitored scientific examination without the need such as paper, papyrus or parchment. In an attempt to
for sampling. separate these constituents visually, the Luv colour space was
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identified as having great potential. The Luv colour space
Visualising separate components of digital images was developed by researchers to overcome problems found
using colour space analysis in other colour spaces where the differences between two
colours were sometimes not perceivable by the human eye.
Christina M. Duffy By describing the colour in terms of one component of
The recent increase in the digitisation of cultural heritage lightness (L), and two components of chromacity (u and v),
material has created vast amounts of digital assets. These those differences were noticeable.
assets undoubtedly enable greater public access and reduce Microscopical examination of fibres in Ming dynasty
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the handling of valuable materials, but have only more paper money highlighted the visual difference between the
recently become recognised as datasets worthy of research in black pigment used to state the terms of the money’s use, and
their own right. the red pigment used for impressing seals indicating the
Digital images are captured in what is known as a colour note’s authenticity. Black pigment was found to be well
space, most typically in the RGB colour space, representing absorbed and attached to pulped fibres resulting in good
the percentage of the red, green and blue components overall legibility (Pl. 19.8). However, red pigment (Pl. 19.9)
combined. This colour space is called trichromatic which was identified as being particulate in nature and not coating
assumes that it is possible to generate any colour using a the fibres as readily as black pigment. This poor distribution
combination of the three primary colours R, G and B. As of red pigment resulted in an overall loss in clarity of the seal
such, any RGB colour space image can be separated into lineation, rendering any study of these demarcations very
three individual monochrome images, which differ in pixel difficult. This was especially the case in areas where the seal
values, providing new ways of visualising an image. This is obscured by overwritten black pigment.
separation of an image into its constituent components can To overcome this illegibility and to generate images
reveal hidden information by highlighting nuances which where the seal and ink could be studied separately, digital
are difficult to distinguish in the combined RGB image. images of the British Library and British Museum Ming
A colour space is not a physical property, but rather an dynasty paper money notes were transformed from their
attribute of visual perception that allows reproducible RGB colour spaces into the LCHLuv colour space. LCHLuv

Paper Money of the Ming Dynasty: Examining the Material Evidence | 175