global illumination computation
High Dynamic Range Image Display
Segmentation and Adaptive Assimilation for Detail-Preserving Display of High-Dynamic Range Images
abstract:Realistic display of high dynamic range images is a difficult problem. Previous methods for high dynamic range image display suffer from halo artifacts or are computationally expensive. We present a novel method for computing local adaptation luminance that can be used with several different visual adaptation based tone-reproduction operators for displaying visually accurate high dynamic range images. The method uses fast image segmentation, grouping and graph operations to generate local adaptation luminance. Results on several images show excellent dynamic range compression while preserving detail, without the presence of halo artifacts. With adaptive assimilation, the method can be configured to bring out high dynamic range appearance in the display image. The method is efficient in terms of processor and memory use.
publication:
Adaptive Gain Control for High Dynamic Range Image Display
abstract:Realistic display of high dynamic range images without introducing any artifact is a hard problem. In this paper we address this problem using a detail preserving local gain control approach. Unlike many other local gain control methods available in the literature, our method is simple, and does not introduce ugly halo artifacts around the high dynamic range edges. We demonstrate the usefulness of this method by showing several examples.
publication:
A Multiscale Model of Adaptation and Spatial Vision for Realistic Image Display
abstract: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 image synthesis algorithms.
publication:
Low Dynamic Range Image Display
A Model of Visual Adaptation for Realistic Image Synthesis
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.
publication:
Time Course Of Adaptation
Time-Dependent Visual Adaptation for Realistic Real-Time Image Display
abstract:Human vision takes time to adapt to large changes in scene inten-sity, 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 time-dependent 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 intentionally simple to allow fast computa-tion, the operator is meant for use with real-time walk-through renderings, high dynamic range video cameras, and other interac-tive applications. We demonstrate its performance on both syn-thetically generated and acquired real-world scenes with large dynamic variations of illumination and contrast.
publication:
|
| university of central florida : graphics group |
