Human vision operates over about nine orders of magnitude, from starlight at 10-4 candelas/meter 2 to daylight at 10 5 cd/m 2. In any given scene, the eye can adapt comfortably over a smaller range of about four orders of magnitude. This still exceeds the dynamic range of conventional display devices and media, which at best cover a range of about 100:1 – only two orders of magnitude. The rest of the information, which would be perceived in the real world as detail in bright and dark regions, is lost above the maximum display value or below the black level. This limitation has serious ramifications for simulated imagery, especially when it is needed to evaluate visual performance or in virtual reality (VR) environments. Previous tone mapping work by Tumblin and Rushmeier 1, Ward 2, and Ferwerda et al 3 did not consider the question of local adaptation. Chiu et al 4 looked into this problem, but their solution resulted in reverse gradients and did not account for human visual response. In this sketch, we present a new method for mapping scenes and images containing high dynamic range information to conventional (and VR) displays. The technique matches object visibility as its primary goal, meaning that objects visible in the real world will be visible on the display, and conversely, objects not visible in the real world will not be visible on the display. As a secondary goal, the method attempts to reproduce a viewer’s subjective response, meaning that the impression of the displayed image should correlate well with memories of the actual scene.

The reflection of light from most materials consists of two major terms: the specular and the diffuse. Specular reflection may be modeled from first principles by considering a rough surface consisting of perfect reflectors, or micro-facets. Diffuse reflection is generally considered to result from multiple scattering either from a rough surface or from within a layer near the surface. Accounting for diffuse reflection by Lambert's Cosine Law, as is universally done in computer graphics, is not a physical theory based on first principles. This paper presents

High contrast scenes are difficult to depict on low contrast displays without loss of important fine details and textures. Skilled artists preserve these details by drawing scene contents in coarseto-fine order using a hierarchy of scene boundaries and shadings. We build a similar hierarchy using multiple instances of a new low curvature image simplifier (LCIS), a partial differential equation inspired by anisotropic diffusion. Each LCIS reduces the scene to many smooth regions that are bounded by sharp gradient discontinuities, and a single parameter K chosen for each LCIS controls region size and boundary complexity. With a few chosen K values (K1>K2>K3:::) LCIS makes a set of progressively simpler images, and image differences form a hierarchy of increasingly important details, boundaries and large features. We construct a high detail, low contrast display image from this hierarchy by compressing only the large features, then adding back all small details. Unlike linear filter hierarchies such as wavelets, filter banks, or image pyramids, LCIS hierarchies do not smooth across scene boundaries, avoiding “halo ” artifacts common to previous contrast reducing methods and some tone reproduction operators. We demonstrate LCIS effectiveness on several example images.

An algorithm is presented that scales the pixel intensities of a computer generated greyscale image so that they are all displayable on a standard CRT. This scaling is spatially nonuniform over the image in that different pixels with the same intensity in the original image may have different intensities in the resulting image. The goal of this scaling transformation is to produce an image on the CRT that perceptually mimics the calculated image, while staying within the physical limitations of the CRT. CR Categories and SubjectDescriptors: I.3.0 [Computer Graphics]:

Realistic image generation is presented in a theoretical formulation that builds from previous work on the rendering equation. Previous and new solution techniques for the global illumination are discussed in the context of this formulation. The basic

. Tone mapping and visual adaptation are crucial for the generation of static, photorealistic images. A largely unexplored problem is the simulation of adaptation and its changes over time on the visual appearance of a scene. These changes are important in interactive applications, including walkthroughs or games, where effects such as dazzling, slow dark-adaptation, or more subtle effects of visual adaptation can greatly enhance the immersive impression. In applications such as driving simulators, these changes must be modeled in order to reproduce the visibility conditions of real-world situations. In this paper, we address the practical issues of interactive tone mapping and propose a simple model of visual adaptation. We describe a multi-pass interactive rendering method that computes the average luminance in a first pass and renders the scene with a tone mapping operator in the second pass. We also propose several extensions to the tone mapping operator of Ferwerda et ...

The physical mechanisms and physiological causes of glare in human vision are reviewed. These mechanisms are scattering in the cornea, lens, and retina, and di#raction in the coherent cell structures on the outer radial areas of the lens. This scattering and di#raction are responsible for the "bloom" and "flare lines" seen around very bright objects. The di#raction e#ects cause the "lenticular halo". The quantitative models of these glare e#ects are reviewed, and an algorithm for using these models to add glare e#ects to digital images is presented. The resulting digital point-spread function is thus psychophysically based and can substantially increase the "perceived" dynamic range of computer simulations containing light sources. Finally, a perceptual test is presented that indicates these added glare e#ects increase the apparent brightness of light sources in digital images. CR Categories and Subject Descriptors: I.3.0 [Computer Graphics]: General; I.3.6 [Computer Graphics]: Method...

The reflection of light from surfaces is a fundamental problem in computer graphics. Although many reflection models have been proposed, few take into account the wave nature of light. In this paper, we derive a new class of reflection models for metallic surfaces that handle the effects of diffraction. Diffraction is a purely wave-like phenomenon and cannot be properly modeled using the ray theory of light alone. A common example of a surface which exhibits diffraction is the compact disk. A characteristic of such surfaces is that they reflect light in a very colorful manner. Our model is also a generalization of most reflection models encountered in computer graphics. In particular, we extend the He-Torrance model to handle anisotropic reflections. This is achieved by rederiving, in a more general setting, results from surface wave physics which were taken for granted by other researchers. Specifically, our use of Fourier analysis has enabled us to tackle the difficult task of analytically computing the Kirchhoff integral of surface scattering.

We consider real-time rendering of scenes in participating media, capturing the effects of light scattering in fog, mist and haze. While a number of sophisticated approaches based on Monte Carlo and finite element simulation have been developed, those methods do not work at interactive rates. The most common real-time methods are essentially simple variants of the OpenGL fog model. While easy to use and specify, that model excludes many important qualitative effects like glows around light sources, the impact of volumetric scattering on the appearance of surfaces such as the diffusing of glossy highlights, and the appearance under complex lighting such as environment maps. In this paper, we present an alternative physically based approach that captures these effects while maintaining realtime performance and the ease-of-use of the OpenGL fog model. Our method is based on an explicit analytic integration of the single scattering light transport equations for an isotropic point light source in a homogeneous participating medium. We can implement the model in modern programmable graphics hardware using a few small numerical lookup tables stored as texture maps. Our model can also be easily adapted to generate the appearances of materials with arbitrary BRDFs, environment map lighting, and precomputed radiance transfer methods, in the presence of participating media. Hence, our techniques can be widely used in real-time rendering. 1

Distribution ray tracing uses Monte Carlo integration to solve the rendering equation. This technique was introduced by Cook et. al, and was notable because of its simplicity and its ability to simulate areal luminaires, camera lens e ects, motion blur, and imperfect specular re ection[5]. Distribution