A classic photographic task is the mapping of the potentially high dynamic range of real world luminances to the low dynamic range of the photographic print. This tone reproduction problem is also faced by computer graphics practitioners who map digital images to a low dynamic range print or screen. The work presented in this paper leverages the time-tested techniques of photographic practice to develop a new tone reproduction operator. In particular, we use and extend the techniques developed by Ansel Adams to deal with digital images. The resulting algorithm is simple and produces good results for a wide variety of images.

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.

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.

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...

Interactive rendering requires rapid visual feedback. The render cache is a new method for achieving this when using high-quality pixel-oriented renderers such as ray tracing that are usually considered too slow for interactive use. The render cache provides visual feedback at a rate faster than the renderer can generate complete frames, at the cost of producing approximate images during camera and object motion. The method works both by caching previous results and reprojecting them to estimate the current image and by directing the renderer's sampling to more rapidly improve subsequent images. Our

We propose a fast, high quality tone mapping technique to display high contrast images on devices with limited dynamic range of luminance values. The method is based on logarithmic compression of luminance values, imitating the human response to light. A bias power function is introduced to adaptively vary logarithmic bases, resulting in good preservation of details and contrast. To improve contrast in dark areas, changes to the gamma correction procedure are proposed. Our adaptive logarithmic mapping technique is capable of producing perceptually tuned images with high dynamic content and works at interactive speed. We demonstrate a successful application of our tone mapping technique with a high dynamic range video player enabling to adjust optimal viewing conditions for any kind of display while taking into account user preference concerning brightness, contrast compression, and detail reproduction.

. 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...

Human vision takes time to adapt to large changes in scene intensity, and these transient adjustments have a profound effect on visual appearance. This paper offers a new operator to include these appearance changes in animations or interactive real-time simulations, and to match a user's visual responses to those the user would experience in a real-world scene. Large, abrupt changes in scene intensities can cause dramatic compression of visual responses, followed by a gradual recovery of normal vision. Asymmetric mechanisms govern these timedependent adjustments, and offer adaptation to increased light that is much more rapid than adjustment to darkness. We derive a new tone reproduction operator that simulates these mechanisms. The operator accepts a stream of scene intensity frames and creates a stream of color display images. All operator components are derived from published quantitative measurements from physiology, psychophysics, color science, and photography. Kept intentiona...

Tone mapping operators are designed to reproduce visibility and the overall impression of brightness, contrast and color of the real world onto limited dynamic range displays and printers. Although many tone mapping operators have been published in recent years, no thorough psychophysical experiments have yet been undertaken to compare such operators against the real scenes they are purporting to depict. In this paper, we present the results of a series of psychophysical experiments to validate six frequently used tone mapping operators against linearly mapped High Dynamic Range (HDR) scenes displayed on a novel HDR device. Individual operators address the tone mapping issue using a variety of approaches and the goals of these techniques are often quite different from one another. Therefore, the purpose of this investigation was not simply to determine which is the "best" algorithm, but more generally to propose an experimental methodology to validate such operators and to determine the participants' impressions of the images produced compared to what is visible on a high contrast ratio display.