Topic
Contrast (vision)
About: Contrast (vision) is a research topic. Over the lifetime, 10379 publications have been published within this topic receiving 221480 citations.
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TL;DR: Binocular interaction experiments showed that binocular summation was absent at all contrast levels, but binocular occlusion was evident at high contrast levels for amblyopic observers, suggesting that two separate mechanisms detect gratings at high and low contrast levels.
Abstract: We have investigated suprathreshold contrast sensitivity and binocular interactions in strabismic and anisometropic amblyopes using a reaction time paradigm. For every spatial frequency, reaction time increased as the grating contrast decreased. At all spatial frequencies and contrast values the reaction times using the amblyopic eye were prolonged compared to the nonamblyopic eye, but most markedly at high spatial frequencies. In the middle range of spatial frequencies, the contrast vs. reaction time function for the nonamblyopic eyes was biphasic, suggesting that two separate mechanisms detect gratings at high and low contrast levels. These functions in deep amblyopia were monotonic, and in shallow amblyopia the break in the functions was present but shifted to lower contrast levels. Binocular interaction experiments showed that binocular summation was absent at all contrast levels, but binocular occlusion was evident at high contrast levels for amblyopic observers.
96 citations
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02 Dec 2013TL;DR: Experimental results on several low contrast images have shown that the proposed adaptive multiscale retinex (AMSR) approach can produce natural and appealing enhanced images.
Abstract: Many people will use digital cameras and camera phones to take images. However, the visual quality (contrast, color rendition, etc.) of some acquired images may be poor due to the limitation of capturing devices or improper illumination conditions, particularly in wide dynamic range scenes. Thus, the images generally consist of both overexposed and underexposed areas. Conventional image enhancement methods may either fail to produce satisfactory and undistorted images, or cannot improve every region of interest appropriately. Single-scale retinex (SSR) and multiscale retinex (MSR), which is defined as a weighted sum of several SSRs, were developed for local image contrast enhancement and dynamic range compression. In this paper, an adaptive multiscale retinex (AMSR) approach will be proposed for image contrast enhancement. In AMSR, the weight associated with each SSR output image is adaptively computed according to the content of the input image in order to produce an enhanced image with natural impression and proper tonal rendition in every region of the image. Experimental results on several low contrast images have shown that our proposed AMSR approach can produce natural and appealing enhanced images.
96 citations
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TL;DR: In this paper, the authors proposed a method to enhance the image quality for a given backlight intensity by performing brightness compensation and local contrast enhancement, where global image statistics and backlight level are considered to maintain the overall brightness of the image.
Abstract: One common way to extend the battery life of a portable device is to reduce the LCD backlight intensity. In contrast to previous approaches that minimize the power consumption by adjusting the backlight intensity frame by frame to reach a specified image quality, the proposed method optimizes the image quality for a given backlight intensity. Image is enhanced by performing brightness compensation and local contrast enhancement. For brightness compensation, global image statistics and backlight level are considered to maintain the overall brightness of the image. For contrast enhancement, the local contrast property of human visual system (HVS) is exploited to enhance the local image details. In addition, a brightness prediction scheme is proposed to speed up the algorithm for display of video sequences. Experimental results are presented to show the performance of the algorithm.
95 citations
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TL;DR: The results indicate that in cerebral cortex the modulation of synchronicity of responses is used as a mechanism complementary to rate changes to enhance the saliency of neuronal responses.
95 citations
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TL;DR: A model of interval discrimination is developed, including an opponent stage between hypothetical spatial coincidence detectors, and the relative contrast of the two bars in an interval discrimination could be randomly perturbed over trials without substantially reducing acuity.
95 citations