Digital Imaging for Cultural Heritage Preservation

Digitizing the Parthenon: Estimating Surface Reflectance under Measured Natural Illumination (Digital Imaging) Part 3

Reflectometry In this section we describe the central reflectometry algorithm used in this work. The basic goal is to determine surface reflectance properties for the scene such that renderings of the scene under captured illumination match photographs of the scene taken under that illumination. We adopt an inverse rendering framework as in [21,29] in which […]

Applications of Spectral Imaging and Reproduction to Cultural Heritage (Digital Imaging) Part 1

Introduction Color images code color information according to three channels, corresponding to the red, green, and blue components of the image acquisition device. In recent years, the field of digital imaging has extended the traditional trichromatic RGB paradigm to more than three dimensions, introducing what is called spectral or multispectral imaging. The aim of multispectral […]

Applications of Spectral Imaging and Reproduction to Cultural Heritage (Digital Imaging) Part 2

Training Set Selection Despite the possibility of estimating reflectance on the basis of smoothing constraints, multispectral imaging systems often rely on training sets. The quality of the reflectance estimation depends on the correlation method and training set selected: it improves if a “good” training set is available while a “bad” training set may negatively affect […]

Applications of Spectral Imaging and Reproduction to Cultural Heritage (Digital Imaging) Part 3

Multispectral Image Reproduction Colorimetric Reproduction The reproduction of multispectral imaging using current colorimetric devices follows an established framework, based on colorimetry as well as on convenient international standards (Figure 7.7). FIGURE 7.7 General scenario for the reproduction of multispectral images on current devices. Multispectral images are converted to colorimetric representations, given a chosen illuminant and […]

Did Early Renaissance Painters Trace Optically Projected Images? The Conclusion of Independent Scientists, Art Historians, and Artists Part 1

Introduction In 2000, the contemporary painter, photographer and set designer David Hockney claimed that some Western artists, as early as 1420, secretly built optical projectors, projected portions of a sunlit scene or subject onto their supports (canvas, panel,…), traced these images and later applied paint [11]. Our thesis is that certain elements in certain paintings […]

Did Early Renaissance Painters Trace Optically Projected Images? The Conclusion of Independent Scientists, Art Historians, and Artists Part 2

Rebuttal The Hockney and Falco claim rested on their unstated and untestable assumption that the specific physical carpet in Lotto’s studio was symmetric, at least to about 2%—roughly their claimed precision of fit. Stork pointed out, however, that such handmade and transported “Lotto carpets” (later named for this artist) were typically asymmetric upon creation and […]

Did Early Renaissance Painters Trace Optically Projected Images? The Conclusion of Independent Scientists, Art Historians, and Artists Part 3

Hans Memling, Flower Still-Life (c. 1490) Given his motivations for the tracing theory as an explanation for the rise in realism, it is a bit unusual that Hockney would claim this Memling work in the Thyssen-Bornemisza Museum in Madrid was executed using optics. After all, the carpet pattern is extremely simple, especially for an artist […]

A Computer Analysis of the Mirror in Hans Memling’s Virgin and Child and Maarten van Nieuwenhove Part 1

Introduction Recently, a number of scholars trained in computer vision, pattern recognition, image processing, computer graphics, and art history have developed methods for addressing problems in the history and interpretation of fine art [45,46]. These methods, when paired with art historical and contextual knowledge, have shown modest but promising successes in authenticating works through statistical […]

A Computer Analysis of the Mirror in Hans Memling’s Virgin and Child and Maarten van Nieuwenhove Part 2

Modeling Reflections Off a Mirror Surface In this section we summarize our main theoretical tools for studying the relationship between the mirror’s location and shape, and corresponding observations. For more details see [27]. Estimating the 3D shape of physical objects is one of the most useful functions of vision. Texture, shading, contour, stereoscopy, motion parallax, […]

Virtual Restoration of Antique Books and Photographs (Digital Imaging) Part 1

Introduction Antique photographs and paper documents constitute an immense patrimony that is distributed among thousands of private and public libraries, museums, and archives all over the world. Despitecare in their conservation, they are based on fragile materials, and hence they are easily affected by environmental agents. In the cases of photographs and documents, frequently the […]

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