We compared how contrast adaptation influences three alternative measures of luminous efficiency. Subjects judged the lightness, the flicker, or the motion of chromatic sine-wave gratings. Adaptation to gratings with correlated luminance and chromatic contrast strongly biases lightness matches and moderately biases minimum-motion settings for gratings that are counterphased at 1 Hz, but it has ...

Experiments were performed to test a set of general-purpose gamut-mapping functions. These gamut-mapping algorithms utilized contrast-preserving scaling functions. These algorithms were tested against the GCUSP gamut-mapping algorithm proposed by Morovic and Luo, which was shown to have very good "universal" gamut-mapping characteristics. The results of these experiments showed that vast improv...

A method lor the determination of lightness from image intensity is presented. For certain classes ot images, lightness corresponds to reflectance, while image intensity is the product of reflectance and illumination intensity. The method is two-dimensional and depends on the different spatial distribution of these two components of image intensity. Such a lightness-judging process is required ...

This paper proposes a Gaussian mixture based image enhancement method which uses particle swarm optimization (PSO) to have an edge over other contemporary methods. The proposed method uses the guassian mixture model to model the lightness histogram of the input image in CIEL*a*b* space. The intersection points of the guassian components in the model are used to partition the lightness histogram...

Experiments have recently been reported in which a decisive change in perceived light~ess was produced by a change in perceived spatial position, with no important change in the retinal image. A number of previous studies had found Little or no such effect. Experiments of the kind that produced these effects and of the kind that do not produce these effects are presented here. The main differen...

Natural viewing challenges the visual system with images that have a dynamic range of light intensity (luminance) that can approach 1,000,000:1 and that often exceeds 10,000:1 [1, 2]. The range of perceived surface reflectance (lightness), however, can be well approximated by the Munsell matte neutral scale (N 2.0/ to N 9.5/), consisting of surfaces whose reflectance varies by about 30:1. Thus,...

When judging the lightness of objects, the visual system has to take into account many factors such as shading, scene geometry, occlusions or transparency. The problem then is to estimate global lightness based on a number of local samples that differ in luminance. Here, we show that eye fixations play a prominent role in this selection process. We explored a special case of transparency for wh...

The earliest thinking about lightness assumed that perceptual experience correlates with local stimulation. Wallach’s (1948) celebrated disk/annulus experiments showed that lightness depends on relative luminance, not absolute luminance, but his ratio theory recognized perceptual structure in only a minimal way. Work following the cognitive revolution showed that lightness depends on (1) depth ...

In a simple two-dimensional (2D) display composed of two uniform surfaces with different luminances, the lightness of the darker surface varies as a function of its relative area while its luminance is held constant (Gilchrist & Radonjić, 2009; Li & Gilchrist, 1999). This phenomenon is known as the area rule of lightness, and although it is extensively studied in the literature, the underlying ...

The light reflected from an object depends on its reflectance, the illumination, and the pose of the object within the scene. An observer is called lightness constant if the perceived reflectance (lightness) of achromatic objects stays the same despite variation in object-extrinsic factors such as illumination and pose. Here, we used a dissimilarity scaling task to measure lightness constancy a...