Texture Vision: A view from Art Conservation
The appreciation of many works of visual art derives from the observation and interpretation of the
object surface. The visual perception of texture is key to interpreting those surfaces, for the texture
provides cues about the nature of the material and the ways in which the artist has manipulated them to
create the object.
The quantification of texture can be undertaken in two ways, by recording the physical topography of
the surface or by analyzing an image that accurately portrays the texture. For the former, 3D mapping
of a surface using an optical profilometer or AFM is usually used when the surface quality requirements
are extremely precise. For most art objects, this description of texture on a microscopic level is not
very useful, since how those surface features are observed by viewers is not directly provided by the
analysis. For this reason, image analysis seems a more promising approach, for in the images the surfaces
will naturally tend to be rendered as they would when viewing the object.
In this study, images of textured surfaces of prototype art objects are analyzed in order to identify
the methods and the metrics that can accurately characterize slight changes in texture. Three main
applications are illustrated: the effect of the conditions of illumination on perceived texture, the
characterization of changes of object due to degradation, and the quantification of the efficiency of
the restoration.
Authors' Info
Dr. Pierre Vernhes received his Industrial Engineer and PhD degrees from Polytechnic University of Grenoble,
Grenoble, France, in 2005 and 2008, respectively. Since 2009, he has been at the Art Conservation Research
Center (ACRC) at Carnegie Mellon University (USA) as a postdoctoral research associate. His main research
interests include texture and image analysis, structure analysis, optical properties of paper and prints,
morphological processing and roughness analysis. He has published several international papers.
Dr. Paul Whitmore was trained as a chemist, getting a B.S. in chemistry from Caltech and a Ph.D. in physical
chemistry from the University of California at Berkeley. He has worked in art conservation science for his
entire professional career, starting at the Environmental Quality Laboratory at Caltech, working with Professor
Glen Cass studying the effects of air pollution on works of art. From there, he went to the Fogg Art Museum at
Harvard University, where he worked as a scientist in what is now the Straus Center for Conservation.
Since 1988 he has been at Carnegie Mellon University, directing the Art Conservation Research Center.
He has recently been appointed a Research Professor in the Department of Chemistry at CMU. His current
research interests are in material degradation chemistries, intrinsic and environmental risk factors for
those processes, remote sensors for material aging, and the consequences of conservation treatments.
He has published on paper deterioration, its treatment, and damage induced by humidity changes; acrylic
paint media stability and the physical damage to acrylic coatings from shrinkage stresses during drying;
fading of colorants from air pollutant exposure; fading of transparent paint glazes from light exposure and
the relationship between photochemical degradation and color changes; and projects utilizing a non-destructive
probe of light stability for colored artifact materials. He has edited a book, Contributions to Conservation
Science, a compilation of research papers published by the first director of the Center, Robert Feller.
He is currently senior editor of the Journal of the American Institute for Conservation.
Contact Info:
Art Conservation Research Center,
Carnegie Mellon University,
700 Technology Drive,
Pittsburgh, PA 15219
pvernhes@cmu.andrew.edu,
pw1j@cmu.andrew.edu