Publications (16)0 Total impact
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Article: Perceptual illumination components: a new approach to efficient, high quality global illumination rendering.
ACM Trans. Graph. 01/2004; 23:742-749. -
Article: Functional Difference Predictors (FDPs):
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ABSTRACT: In this paper we introduce Functional Difference Predictors (FDPs), a new class of perceptually-based image difference metrics that predict how image errors affect the ability to perform visual tasks using the images. To define the properties of FDPs, we conduct a psychophysical experiment that focuses on two visual tasks: spatial layout and material estimation. In the experiment we introduce errors in the positions and contrasts of objects reflected in glossy surfaces and ask subjects to make layout and material judgments. The results indicate that layout estimation depends only on positional errors in the reflections and material estimation depends only on contrast errors. These results suggest that in many task contexts, large visible image errors may be tolerated without loss in task performance, and that FDPs may be better predictors of the relationship between errors and performance than current Visible Difference Predictors (VDPs).12/2003; -
Article: Three Varieties of Realism in Computer Graphics
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ABSTRACT: This paper describes three varieties of realism that need to be considered in evaluating computer graphics images and defines the criteria that need to be met if each kind of realism is to be achieved. The paper introduces a conceptual framework for thinking about realism in images, and describes a set of research tools for measuring image realism and assessing its value in graphics applications.03/2003; -
Article: Perceptually-driven decision theory for interactive realistic rendering.
ACM Trans. Graph. 01/2003; 22:152-181. -
Article: A Spatial Post-Processing Algorithm for
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ABSTRACT: The standard technique for making images viewed at daytime lighting levels look like images of night scenes is to use a low overall contrast, low overall brightnesses, desaturation, and to give the image a "blue shift". This paper introduces two other important e#ects associated with viewing real night scenes: visible noise, and the loss of acuity with little corresponding perceived blur.10/2002; -
Article: A Perceptually-Based Texture Caching Algorithm for
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ABSTRACT: The performance of hardware-based interactive rendering systems is often constrained by polygon fill rates and texture map capacity, rather than polygon count alone. We present a new software texture caching algorithm that optimizes the use of texture memory in current graphics hardware by dynamically allocating more memory to the textures that have the greatest visual importance in the scene. The algorithm employs a resource allocation scheme that decides which resolution to use for each texture in board memory. The allocation scheme estimates the visual importance of textures using a perceptually-based metric that takes into account view point and vertex illumination as well as texture contrast and frequency content. This approach provides high frame rates while maximizing image quality.07/2001; -
Article: A Perceptually-Based Texture Caching Algorithm for Hardware-Based Rendering
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ABSTRACT: The performance of hardware-based interactive rendering systems is often constrained by polygon fill rates and texture map capacity, rather than polygon count alone. We present a new software texture caching algorithm that optimizes the use of texture memory in current graphics hardware by dynamically allocating more memory to the textures that have the greatest visual importance in the scene. The algorithm employs a resource allocation scheme that decides which resolution to use for each texture in board memory. The allocation scheme estimates the visual importance of textures using a perceptually-based metric that takes into account view point and vertex illumination as well as texture contrast and frequency content. This approach provides high frame rates while maximizing image quality.06/2001; -
Article: Night Rendering
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ABSTRACT: The issues of realistically rendering naturally illuminated scenes at night are examined. This requires accurate models for moonlight, night skylight, and starlight. In addition, several issues in tone reproduction are discussed: eliminatiing high frequency information invisible to scotopic (night vision) observers; representing the flare lines around stars; determining the dominant hue for the displayed image. The lighting and tone reproduction are shown on a variety of models.09/2000; -
Article: Toward a Psychophysically-Based
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ABSTRACT: image synthesis based on experimental studies of surface gloss perception. To develop the model, we've conducted two experiments that explore the relationships between the physical parameters used to describe the reflectance properties of glossy surfaces and the perceptual dimensions of glossy appearance. In the first experiment we use multidimensional scaling techniques to reveal the dimensionality of gloss perception for simulated painted surfaces. In the second experiment we use magnitude estimation methods to place metrics on these dimensions that relate changes in apparent gloss to variations in surface reflectance properties. We use the results of these experiments to rewrite the parameters of a physically-based light reflection model in perceptual terms. The result is a new psychophysically-based light reflection model where the dimensions of the model are perceptually meaningful, and variations along the dimensions are perceptually uniform. We demonstrate that the model can facilitate describing surface gloss in graphics rendering applications. This work represents a new methodology for developing light reflection models for image synthesis.09/2000; -
Conference Proceeding: Toward a psychophysically-based light reflection model for image synthesis.
01/2000 -
Article: Validation of Global Illumination Simulations through CCD Camera Measurements
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ABSTRACT: In this paper we present a technique for calibrating a CCD camera for direct colorimetric comparison between the captured images of the real environment and synthetic images of the simulated environments. We use this comparison to validate lighting simulation algorithms used for computing synthetic images. 1. Introduction For nearly 25 years one of the main research efforts at the Cornell Program of Computer Graphics has been the development of algorithms for physically accurate simulation of light transport in environments [Goral84, Cohen86, Sillion91, Smits94, Walter97]. Given the geometry of the physical scene, and the spectral and directional surface reflectance and emittance values of surfaces, these algorithms can compute the spectral radiance at any point in the scene. If these algorithms are to become predictive then it is important to validate the results computed by these algorithms with experimental comparisons. To carry out experimental comparisons we have set up a light...10/1999; -
Article: A Multiscale Model of Adaptation and Spatial Vision for Realistic Image Display
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ABSTRACT: In this paper we develop a computational model of adaptation and spatial vision for realistic tone reproduction. The model is based on a multiscale representation of pattern, luminance, and color processing in the human visual system. We incorporate the model into a tone reproduction operator that maps the vast ranges of radiances found in real and synthetic scenes into the small fixed ranges available on conventional display devices such as CRT's and printers. The model allows the operator to address the two major problems in realistic tone reproduction: wide absolute range and high dynamic range scenes can be displayed; and the displayed images match our perceptions of the scenes at both threshold and suprathreshold levels to the degree possible given a particular display device. Although in this paper we apply our visual model to the tone reproduction problem, the model is general and can be usefully applied to image quality metrics, image compression methods, and perceptually-based...06/1998; -
Article: A Model of Visual Masking for Computer Graphics
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ABSTRACT: In this paper we develop a computational model of visual masking based on psychophysical data. The model predicts how the presence of one visual pattern affects the detectability of another. The model allows us to choose texture patterns for computer graphics images that hide the effects of faceting, banding, aliasing, noise and other visual artifacts produced by sources of error in graphics algorithms. We demonstrate the utility of the model by choosing a texture pattern to mask faceting artifacts caused by polygonal tesselation of a flat-shaded curved surface. The model predicts how changes in the contrast, spatial frequency, and orientation of the texture pattern, or changes in the tesselation of the surface will alter the masking effect. The model is general and has uses in geometric modeling, realistic image synthesis, scientific visualization, image compression, and image-based rendering.07/1997; -
Conference Proceeding: A model of visual masking for computer graphics.
01/1997 -
Conference Proceeding: A framework for realistic image synthesis.
01/1997 -
Article: A Model of Visual Adaptation for Realistic Image Synthesis
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ABSTRACT: In this paper we develop a computational model of visual adaptation for realistic image synthesis based on psychophysical experiments. The model captures the changes in threshold visibility, color appearance, visual acuity, and sensitivity over time that are caused by the visual system's adaptation mechanisms. We use the model to display the results of global illumination simulations illuminated at intensities ranging from daylight down to starlight. The resulting images better capture the visual characteristics of scenes viewed over a wide range of illumination levels. Because the model is based on psychophysical data it can be used to predict the visibility and appearance of scene features. This allows the model to be used as the basis of perceptually-based error metrics for limiting the precision of global illumination computations. CR Categories and Subject Descriptors: I.3.0 [Computer Graphics]: General; I.3.6 [Computer Graphics]: Methodology and Techniques. Additional Key Words...07/1996;
Top co-authors
Institutions
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1996–2004
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Cornell University
New York City, NY, USA
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