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Objects in the natural world possess different visual attributes, including shape, colour, surface texture and motion. Previous perceptual studies have assumed that the brain analyses the colour of a surface independently of its three-dimensional shape and viewing geometry, although there are neural connections between colour and two-dimensional form(More)
In the companion study (C. Ripamonti et al., 2004), we present data that measure the effect of surface slant on perceived lightness. Observers are neither perfectly lightness constant nor luminance matchers, and there is considerable individual variation in performance. This work develops a parametric model that accounts for how each observer's lightness(More)
In this study human color constancy was tested for two-dimensional (2D) and three-dimensional (3D) setups with real objects and lights. Four different illuminant changes, a natural selection task and a wide choice of target colors were used. We found that color constancy was better when the target color was learned as a 3D object in a cue-rich 3D scene than(More)
In this paper we present a new technique for the display of High Dynamic Range (HDR) images on Low Dynamic Range (LDR) displays. The described process has three stages. First, the input image is segmented into luminance zones. Second, the tone mapping operator (TMO) that performs better in each zone is automatically selected. Finally, the resulting tone(More)
In this paper, we investigate how controlled changes to image properties and orientation affect eye movements for repeated viewings of images of natural scenes. We make changes to images by manipulating low-level image content (such as luminance or chromaticity) and/or inverting the image. We measure the effects of these manipulations on human scanpaths(More)
Image gradients--smooth changes in color and luminance--may be caused by intrinsic surface reflectance properties or extrinsic illumination phenomena, including shading, shadowing, and inter-reflections. In turn, image gradients may provide the visual system with information concerning the origin of these factors, such as the orientation of surfaces with(More)
We explore the relative utility of shape from shading and binocular disparity for depth perception. Ray-traced images either featured a smooth surface illuminated from above (shading-only) or were defined by small dots (disparity-only). Observers judged which of a pair of smoothly curved convex objects had most depth. The shading cue was around half as(More)
In recent years inverse tone mapping techniques have been proposed for enhancing low-dynamic range (LDR) content for a high-dynamic range (HDR) experience on HDR displays, and for image based lighting. In this paper, we present a psychophysical study to evaluate the performance of inverse (reverse) tone mapping algorithms. Some of these techniques are(More)
In the last few years, researchers in the field of High Dynamic Range (HDR) Imaging have focused on providing tools for expanding Low Dynamic Range (LDR) content for the generation of HDR images due to the growing popularity of HDR in applications, such as photography and rendering via Image-Based Lighting, and the imminent arrival of HDR displays to the(More)
When colourimetrically characterising a high dynamic range display (HDR) built from an LCD panel and an LED backlight one is faced with several problems: the channels may not be constant; they may not be independent and there may be a significant radiant output at the black level. But crucially, colour transforms are underdetermined, which means that the(More)