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Colour is an important source of information in the natural world. It can be used for distinguishing and identifying surfaces and objects and separating one region from another. For instance, flowers and grasses in a garden can be distinguished by their colours despite a change in illuminant. Intuitively, the identifiability of surfaces in a scene can be described by their volumes of colour gamuts. But is this approximation of the identifiability accurate? On the other hand, the existence of metamerism in natural scenes shows that colour is sometimes unreliable for surfaces identification. Estimating frequency of metamerism normally requires many comparisons between surface colours to determine their distinguishability under different illuminants. Is there a simpler approach to predict the frequency of metamerism in natural scenes? The aim of this thesis was to address these two questions about the identifiability of surfaces in natural scenes. To answer the first question, the volumes of colour gamuts were estimated over 50 natural scenes under different illuminants. The logarithm of the gamut volume was regressed on the differential entropy of colours. It was found that gamut volume can be an accurate approximation, given a colour difference threshold representing the visual distinguishability within an approximately perceptually uniform colour space. To answer the second question, the frequency of metamerism was estimated over 50 natural scenes with changes in illuminant; and predictive models were constructed based on different combinations of Shannon differential entropies of colours. There was strong dependence of the frequency of metamerism on the combination of the differential entropy and the conditional differential entropy of colours. It means that the frequency of metamerism can be predicted by the informational quantities of the colours in a scene.

The human visual system is trichromatic and therefore reduces higher dimensional spectral data to three dimensions. Two stimuli with different spectral power curve shapes can result in the same cone response and therefore match each other. Color reproduction systems take advantage of this effect and match color by creating the same cone response as the original but with different colorants. ICC color management transforms all colors into a three-dimensional reference color space, which is independent from any input or output devices. This concept works well for a single defined observer and illumination conditions, but in practice, it is not possible to control viewing conditions leading to severe color mismatches, particularly for paintings. Paintings pose unique challenges because of the large variety of available colorants resulting in a very large color gamut and considerable spectral variability. This research explored spectral color reproduction using a seven-color electrophotographic printing process, the HP Indigo 7000. Because of the restriction to seven inks from the 12 basic inks supplied with the press, the research identified both the optimal seven inks and a set of eight artist paints which can be spectrally reproduced. The set of inks was Cyan, Magenta, Yellow, Black, Reflex Blue, Violet and Orange. The eight paints were Cadmium Red Medium, Cadmium Orange, Cadmium Yellow Light, Dioxazine Purple, Phthalo Blue Green Shade, Ultramarine Blue, Quinacridone Crimson and Carbon Black. The selection was based on both theoretical and experimental analyses. The final testing was computational indicating the possibility of both spectral and colorimetric color reproduction of paintings.

Two- and three-dimensional micro-computed tomography was used to quantify human molar tissues from a whole-crown perspective. This study tested how the sexes differ in their crown tissue components, how dental tissues are distributed throughout a molar and along the molar row, if measurements from different planes of section can predict the whole-crown condition, and whether hypocone or hypoconulid expression influences crown tissue component measurements.Males significantly differed from females by having relatively thinner enamel in their lower molars and absolutely thicker enamel (and greater enamel quantity) in their upper molars, in particular in the UM1 and the protocone, which was attributed to function; however, females have a greater proportion of enamel in their molars compared to males. Furthermore, males had significantly greater dentine quantity, enamel-dentine junction (EDJ) length and surface area (few significant shape differences were found), basal-crown diameter and area, more widely-spaced and taller dentine horns, and taller dentine crowns. Combining the sexes for some analyses is therefore not appropriate, and comparisons of crown components of fossil hominin should take into account the possibility that some of the variation may be a result of sex rather than species differences.Discriminant function analysis identified crown components of UM2 (volume), LM1 (distal section) and UM1 (buccal section) as being the most significant sex discriminators with an accuracy of 75% to 100% correct classification. Significant metameric differences in crown components were discerned. Although molars differed from each other in EDJ size and shape, considerable overlap precludes the separation of molars. Furthermore, enamel thickness components increased from M1 to M3 while other crown components decreased. The mesial-to-distal increase in enamel thickness within molars is part of the greater trend of increasing thickness along the molar row. Enamel and dentine volume were reliably predicted from different virtual planes of section, demonstrating their utility in reconstructing the whole-crown condition in worn and broken specimens. Furthermore, hypocone and hypoconulid expression significantly influenced the measurements of dentine area, EDJ length, and bi-cervical diameter in the distal and lingual sections of M2 and M3. Enamel thickness components were not significantly affected by trait expression in two- or three-dimensions.