iCAM06 is a high dynamic range (HDR) imaging technology. However, the base-detail separation, chromatic adaptation, and tone compression algorithms included in iCAM06 cause problems in image quality. This study focuses on the desaturation, poor contrast, and noise problems found in the dark regions. First, we discuss desaturation compensation using the visual acuity characteristics for various ...

The purpose of this work is to describe how the visual system groups surfaces of unequal lightness under complex patterns of illumination. We propose that the Gestalt principle of Grouping by Regularity explains this process better than the more often cited principle of Grouping by Similarity. In our first experiment we demonstrate that in a perceptual organization task, pitting proximity again...

The presence of multiple illuminants in an image is an obstacle for many computer vision algorithms as well as most illuminant estimation algorithms. Multiply lit scenes do, however, occur in many situations, such as the presence of shadows or daytime indoor environments. Common ways to minimize the problems created by multiple lights are to perform a given task only in regions containing a sin...

Two kinds of constancy underlie the everyday perception of surface colour: constancy under changes in illuminant and constancy under changes in surface position. Classically, these two constancies seem to place conflicting demands on the visual system: to both take into account the region surrounding a surface and also discount it. It is shown here, however, that the ability of observers to mak...

We report the results of matching experiments designed to study the color appearance of objects rendered under different simulated illuminants on a CRT monitor. Subjects set asymmetric color matches between a standard object and a test object that were rendered under illuminants with different spectral power distributions. For any illuminant change, we found that the mapping between the cone co...

The color of a scene recorded by a trichromatic sensor varies with the spectral distribution of the illuminant. For recognition and many other applications, we seek to process these measurements to obtain a color representation that is unaffected by illumination changes. Achieving such color constancy is an ill-posed problem because both the spectral distribution of the illuminant and the scene...

People readily perceive smooth luminance variations as being due to the shading produced by undulations of a 3-D surface (shape-from-shading). In doing so, the visual system must simultaneously estimate the shape of the surface and the nature of the illumination. Remarkably, shape-from-shading operates even when both these properties are unknown and neither can be estimated directly from the im...

The physical inputs to our visual system are dictated by the interplay between lights and surfaces; thus, for surface color be stably perceived, influence of illuminant must discounted. To reveal strategy infer color, we conducted three psychophysical experiments designed test optimal hypothesis that internalize gamut under various illuminants apply prior estimate color. In each experiment, pre...