Advances in multispectral and hyperspectral imaging for archaeology and art conservation

Multispectral imaging has been applied to the field of art conservation and art history since the early 1990s. It is attractive as a noninvasive imaging technique because it is fast and hence capable of imaging large areas of an object giving both spatial and spectral information. This paper gives an overview of the different instrumental designs, image processing techniques and various applications of multispectral and hyperspectral imaging to art conservation, art history and archaeology. Recent advances in the development of remote and versatile multispectral and hyperspectral imaging as well as techniques in pigment identification will be presented. Future prospects including combination of spectral imaging with other noninvasive imaging and analytical techniques will be discussed

Evaluation of contrast measures in relation to observers perceived contrast

We have carried out a psychophysical experiment to register perceived contrast. 17 observers viewed 15 images, each image was shown for 40 seconds where the observer stated the perceived contrast of the image. The results from the observers indicate that the consensus of contrast among experts decreases as the perceived contrast decreases. Experts also rate the contrast higher then non-experts. A number of contrast algorithms, developed to predict perceived contrast was evaluated against the perceived contrast from the observers

Multispectral Imaging in Multimedia

this paper we investigate the colorimetric simulation of a scene as viewed under different illuminants. Applied to fine arts paintings, museological objects, jewelry, textiles, etc., such simulations could be of particular interest as a multimedia application. It is well known that the appearance of an object or a scene may change considerably when the illuminant changes, due to physical and psychophysical effects. These effects are taken into account in most colour appearance models in a somewhat heuristic manner. However, such models can not predict correctly changes for arbitrary illuminants, one important reason for this being metamerism. To be able to predict quantitatively the physical phenomena involved in a change between any illuminants, a more complete spectral description of the illuminants and the scene reflectances is needed. The acquisition of multispectral images is thus required. A multispectral image is an image where each pixel contains information about the spectral reflectance of the imaged scene. Multispectral images carry information about a number of spectral bands: from three components per pixel for colour images to several hundreds of bands for hyperspectral images. Multispectral imaging is relevant to several domains of application, such as remote sensing [1], physics, analysis of museological objects [2], cosmetics, medicine [3], high-accuracy colour printing, or computer graphics [4]. Hyperspectral image acquisition systems are complex and expensive, limiting their current use mainly to remote sensing applications. Multispectral scanners are mostly based on a point-scan scheme [5], and are thus too slow for our applications