The Experts below are selected from a list of 1107 Experts worldwide ranked by ideXlab platform

Lei Wang - One of the best experts on this subject based on the ideXlab platform.

  • The Study of Retroreflective Material Based on Mesopic Vision Theory
    2016
    Co-Authors: Chuan Zheng Zhu, Yong Yang, Lei Wang
    Abstract:

    spectrum Abstract. The coefficient of retroreflection is considered as the most important parameter of retroreflective material, the value of which is tested by photopic detector now. In fact this material were usually used under Mesopic Vision condition, and through the test of retroreflective spectra, the Mesopic spectral luminous efficiency Vmes(λ) and equivalent brightness were calculated. The result show that at different brightness the retroreflective light present unlike spectrum distribution, and white, blue material with higher retroreflection value under Mesopic Vision, red material own lower value, this phenomenon is more apparent with the decrease of brightness

  • Influence of Sign Retro-Reflection with Vehicle Headlights under Mesopic Vision Conditions
    ICTE 2013, 2013
    Co-Authors: Lei Wang, Zhu Chuanzheng, Yang Yong, Yuanyuan Bai, Wang Yao
    Abstract:

    Coefficient of retro-reflection (COR) is one of the most important parameters in evaluating visual performance of highway signs. The value of this parameter is influenced by geometric condition, material structure, and so on. For the various retro-reflective materials characteristic different reflectance spectra, these materials show colors as white, red, etc., with the lighting from headlights. In recent years, Xenon and white light emitting diodes (LEDs) were used as vehicle headlights, compared with Halogen lamp (light source A), the reflectance spectra on the same retro-reflection sign are not the same. For the region of reflective brightness, the Mesopic Vision theory was used to analysis the COR influenced by headlights. Based on existing test conditions the Mesopic spectral luminous efficiency and equivalent brightness were calculated. The results show that the gain of equivalent visual brightness depend on surface brightness, overlay of sources, and reflectance spectra; light sources with wide-band spectra show higher gain level than traditional light sources.

  • the study of retroreflective material based on Mesopic Vision theory
    Applied Mechanics and Materials, 2012
    Co-Authors: Chuan Zheng Zhu, Yong Yang, Lei Wang
    Abstract:

    The coefficient of retroreflection is considered as the most important parameter of retroreflective material, the value of which is tested by photopic detector now. In fact this material were usually used under Mesopic Vision condition, and through the test of retroreflective spectra, the Mesopic spectral luminous efficiency Vmes(λ) and equivalent brightness were calculated. The result show that at different brightness the retroreflective light present unlike spectrum distribution, and white, blue material with higher retroreflection value under Mesopic Vision, red material own lower value, this phenomenon is more apparent with the decrease of brightness.

  • Study on the Highway Tunnel Lighting with Spectrum Superposition
    Advanced Materials Research, 2012
    Co-Authors: Yong Yang, Lei Wang
    Abstract:

    The lighting level of highway tunnel is usually under Mesopic Vision condition, but the traditional luminance and illuminance test are corrected by photopic Vision spectral luminous efficiency. According to the difference of spectral luminous efficiency between photopic and Mesopic, the lighting with different peak wavelength would provide various ratios of radiation / photometric flux. Four kinds of narrowband light sources with the same tested flux were stacked up in white LED and HPS respectively, through equivalent brightness calculation, the most efficient spectral wavelength were obtained under Mesopic condition.

  • Study on the Highway Tunnel Lighting with Spectrum Superposition
    Advanced Materials Research, 2012
    Co-Authors: Yong Yang, Lei Wang
    Abstract:

    The lighting level of highway tunnel is usually under Mesopic Vision condition, but the traditional luminance and illuminance test are corrected by photopic Vision spectral luminous efficiency. According to the difference of spectral luminous efficiency between photopic and Mesopic, the lighting with different peak wavelength would provide various ratios of radiation / photometric flux. Four kinds of narrowband light sources with the same tested flux were stacked up in white LED and HPS respectively, through equivalent brightness calculation, the most efficient spectral wavelength were obtained under Mesopic condition.

Yong Yang - One of the best experts on this subject based on the ideXlab platform.

  • The Study of Retroreflective Material Based on Mesopic Vision Theory
    2016
    Co-Authors: Chuan Zheng Zhu, Yong Yang, Lei Wang
    Abstract:

    spectrum Abstract. The coefficient of retroreflection is considered as the most important parameter of retroreflective material, the value of which is tested by photopic detector now. In fact this material were usually used under Mesopic Vision condition, and through the test of retroreflective spectra, the Mesopic spectral luminous efficiency Vmes(λ) and equivalent brightness were calculated. The result show that at different brightness the retroreflective light present unlike spectrum distribution, and white, blue material with higher retroreflection value under Mesopic Vision, red material own lower value, this phenomenon is more apparent with the decrease of brightness

  • The performance analysis for lighting sources in highway tunnel based on visual function
    Spectroscopy and Spectral Analysis, 2015
    Co-Authors: Yong Yang, Haifeng Jiang
    Abstract:

    Under the condition of Mesopic Vision, the spectral luminous efficiency function is shown as a series of curves. Its peak wavelength and intensity are affected by light spectrum, background brightness and other aspects. The impact of light source to lighting visibility could not be carried out via a single optical parametric characterization. The reaction time of visual cognition is regard as evaluating indexes in this experiment. Under the condition of different speed and luminous environment, testing visual cognition based on Vision function method. The light sources include high pressure sodium, electrodeless fluorescent lamp and white LED with three kinds of color temperature (the range of color temperature is from 1 958 to 5 537 K). The background brightness value is used for basic section of highway tunnel illumination and general outdoor illumination, its range is between 1 and 5 cd x m(-)2. All values are in the scope of Mesopic Vision. Test results show that: under the same condition of speed and luminance, the reaction time of visual cognition that corresponding to high color temperature of light source is shorter than it corresponding to low color temperature; the reaction time corresponding to visual target in high speed is shorter than it in low speed. At the end moment, however, the visual angle of target in observer's visual field that corresponding to low speed was larger than it corresponding to high speed. Based on MOVE model, calculating the equivalent luminance of human Mesopic Vision, which is on condition of different emission spectrum and background brightness that formed by test lighting sources. Compared with photopic Vision result, the standard deviation (CV) of time-reaction curve corresponding to equivalent brightness of Mesopic Vision is smaller. Under the condition of Mesopic Vision, the discrepancy between equivalent brightness of different lighting source and photopic Vision, that is one of the main reasons for causing the discrepancy of visual recognition. The emission spectrum peak of GaN chip is approximate to the wave length peak of efficiency function in photopic Vision. The lighting visual effect of write LED in high color temperature is better than it in low color temperature and electrodeless fluorescent lamp. The lighting visual effect of high pressure sodium is weak. Because of its peak value is around the Na+ characteristic spectra. Language: zh

  • The Performance Analysis for Lighting Sources in Highway Tunnel Based on Visual Function
    Guang pu xue yu guang pu fen xi, 2015
    Co-Authors: Yong Yang, Wenyuan Han, Haifeng Jiang, Ming Yan, Liwei Zhu
    Abstract:

    Under the condition of Mesopic Vision, the spectral luminous efficiency function is shown as a series of curves. Its peak wavelength and intensity are affected by light spectrum, background brightness and other aspects. The impact of light source to lighting visibility could not be carried out via a single optical parametric characterization. The reaction time of visual cognition is regard as evaluating indexes in this experiment. Under the condition of different speed and luminous environment, testing visual cognition based on Vision function method. The light sources include high pressure sodium, electrodeless fluorescent lamp and white LED with three kinds of color temperature (the range of color temperature is from 1 958 to 5 537 K). The background brightness value is used for basic section of highway tunnel illumination and general outdoor illumination, its range is between 1 and 5 cd x m(-)2. All values are in the scope of Mesopic Vision. Test results show that: under the same condition of speed and luminance, the reaction time of visual cognition that corresponding to high color temperature of light source is shorter than it corresponding to low color temperature; the reaction time corresponding to visual target in high speed is shorter than it in low speed. At the end moment, however, the visual angle of target in observer's visual field that corresponding to low speed was larger than it corresponding to high speed. Based on MOVE model, calculating the equivalent luminance of human Mesopic Vision, which is on condition of different emission spectrum and background brightness that formed by test lighting sources. Compared with photopic Vision result, the standard deviation (CV) of time-reaction curve corresponding to equivalent brightness of Mesopic Vision is smaller. Under the condition of Mesopic Vision, the discrepancy between equivalent brightness of different lighting source and photopic Vision, that is one of the main reasons for causing the discrepancy of visual recognition. The emission spectrum peak of GaN chip is approximate to the wave length peak of efficiency function in photopic Vision. The lighting visual effect of write LED in high color temperature is better than it in low color temperature and electrodeless fluorescent lamp. The lighting visual effect of high pressure sodium is weak. Because of its peak value is around the Na+ characteristic spectra.

  • the study of retroreflective material based on Mesopic Vision theory
    Applied Mechanics and Materials, 2012
    Co-Authors: Chuan Zheng Zhu, Yong Yang, Lei Wang
    Abstract:

    The coefficient of retroreflection is considered as the most important parameter of retroreflective material, the value of which is tested by photopic detector now. In fact this material were usually used under Mesopic Vision condition, and through the test of retroreflective spectra, the Mesopic spectral luminous efficiency Vmes(λ) and equivalent brightness were calculated. The result show that at different brightness the retroreflective light present unlike spectrum distribution, and white, blue material with higher retroreflection value under Mesopic Vision, red material own lower value, this phenomenon is more apparent with the decrease of brightness.

  • Study on the Highway Tunnel Lighting with Spectrum Superposition
    Advanced Materials Research, 2012
    Co-Authors: Yong Yang, Lei Wang
    Abstract:

    The lighting level of highway tunnel is usually under Mesopic Vision condition, but the traditional luminance and illuminance test are corrected by photopic Vision spectral luminous efficiency. According to the difference of spectral luminous efficiency between photopic and Mesopic, the lighting with different peak wavelength would provide various ratios of radiation / photometric flux. Four kinds of narrowband light sources with the same tested flux were stacked up in white LED and HPS respectively, through equivalent brightness calculation, the most efficient spectral wavelength were obtained under Mesopic condition.

Tatsuto Takeuchi - One of the best experts on this subject based on the ideXlab platform.

  • Motion perception under Mesopic Vision.
    Journal of Vision, 2016
    Co-Authors: Sanae Yoshimoto, Katsunori Okajima, Tatsuto Takeuchi
    Abstract:

    Mesopic and scotopic Vision extend over an illuminance range of 106. The goal of the present study was to determine the effect of decreasing light level on the underlying motion mechanism that integrates spatiotemporally separated motion signals. To accomplish this, we took advantage of the phenomenon of visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the directional movement of a preceding priming stimulus. After terminating a drifting priming stimulus, a 180° phase-shifted grating was presented as a test stimulus. The priming and test stimuli were separately presented to the central and peripheral retinas, respectively. The participants judged the perceived direction of this test stimulus at various light levels from photopic to scotopic levels. We found that the effects of motion priming disappeared over 1 log unit of Mesopic light levels. When the test stimulus was presented before the offset of the priming stimulus to compensate for the temporal delay in the rod pathway or when both stimuli were presented at the same location in the periphery, a motion-priming effect appeared at Mesopic light levels. These results suggest that different temporal characteristics between the cone pathway and rod pathway disturb the function of the putative motion mechanism responsible for the spatiotemporal integration of motion signals, which leads to specific modulation of motion perception over a wide range of Mesopic Vision.

  • Effect of light level on the reference frames of visual motion processing.
    Journal of Vision, 2014
    Co-Authors: Sanae Yoshimoto, Mariko Uchida-ota, Tatsuto Takeuchi
    Abstract:

    It is empirically known that some action-related visual tasks, which may rely on the construction of spatiotopic coordinates, are not well conducted under Mesopic Vision. The aim of this study was to clarify the effect of light level on the reference frame, such as retinotopic and spatiotopic coordinate bases, associated with visual motion processing. For this purpose, we used a phenomenon called visual motion priming in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a priming stimulus. Previous studies have shown that negative and positive motion priming are conspicuously observed in retinotopic and spatiotopic coordinates, respectively. In the experiments, participants made a saccade after the termination of the priming stimulus and judged the perceived direction of the test stimulus presented subsequently in retinotopic or spatiotopic coordinates at different light levels. We found that in retinotopic coordinates, negative motion priming was observed at all light levels. In spatiotopic coordinates, positive motion priming was observed at photopic and scotopic light levels, whereas the strength of motion priming was greatly reduced at Mesopic light levels. These results were robust to the change in the luminance contrast or the saccadic eye movement per se. Different spatiotemporal properties of cones and rods at Mesopic light levels may disturb the construction of a spatiotopic representation of motion, which leads to the disappearance of visual motion priming in spatiotopic coordinates during Mesopic Vision.

  • Visual motion priming reveals why motion perception deteriorates during Mesopic Vision.
    Journal of Vision, 2013
    Co-Authors: Sanae Yoshimoto, Tatsuto Takeuchi
    Abstract:

    We know empirically that the perception of moving objects deteriorates under Mesopic Vision, in which both rods and cones operate. The purpose of this study was to examine the cause of this degradation. We utilized a phenomenon called visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a preceding stimulus. The spatial distances between the priming and the test stimuli were varied. At Mesopic light levels, a stimulus that is presented at the central retina is presumably processed by the cone system, while a stimulus that is presented at the peripheral retina is processed by the rod system (Raphael & MacLeod, 2011). Subjects judged the perceived direction of 180° phase-shifted sine-wave grating that was followed by a smoothly drifting priming stimulus under different retinal illuminances. We found that, under Mesopic conditions, the strength of motion priming was greatly reduced when the priming and test stimuli were presented separately at the center and the periphery, respectively. In contrast, motion priming was perceived in most of the trials under photopic and scotopic conditions or when both the priming and test stimuli were presented at the central retina under Mesopic conditions. When the priming and test stimuli temporally overlapped, motion priming was conspicuous irrespective of the retinal illuminance. These results suggest that the incompleteness in the integration of signals that was induced by the temporal delay of rod pathways caused the degradation of motion perception under Mesopic Vision.

  • Reversal of visual motion priming under Mesopic Vision
    Japanese Journal of Psychology, 2012
    Co-Authors: Sanae Yoshimoto, Tatsuto Takeuchi
    Abstract:

    : It is known that a directionally ambiguous test stimulus is perceived to move in the same direction as a brief preceding priming stimulus when both stimuli are presented at the same retinal location (visual motion priming). To examine the spatial properties of visual motion priming under different retinal illuminance, we manipulated the distance between the priming and test stimuli. Participants judged the perceived direction of 180 deg phase-shifted, thus directionally ambiguous, sine-wave gratings (test stimulus) displayed immediately after the offset of a smoothly drifting priming stimulus. The distance between priming and test stimuli was varied from 0 to 10 deg in visual angle. Since the spatial summation area broadens under low retinal illuminance, we predicted that visual motion priming would be more conspicuous under Mesopic Vision than under photopic Vision. Contrary to this prediction, as the retinal illuminance decreased and the distance between the primer and the test stimulus increased, the test stimulus was perceived to move in the direction opposite to the priming stimulus. We speculate that different motion integration systems are functioning depending on the retinal illuminance.

  • P3-17: Why is it Difficult to See Moving Objects in the Dusk? Visual Motion Priming Reveals Two Motion Mechanisms Functioning under Mesopic Vision
    i-Perception, 2012
    Co-Authors: Sanae Yoshimoto, Tatsuto Takeuchi
    Abstract:

    We know empirically that perception of moving objects deteriorates in the dusk. The purpose of this study is to reveal the reason of such sensitivity degradation under Mesopic Vision, when both cones and rods operate. For the purpose, we utilized a phenomenon called visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a preceding priming stimulus. Participants judged the perceived direction of 180 deg phase-shifted, thus directionally ambiguous, sine-wave grating (test stimulus) followed by a smoothly drifting priming stimulus under three different retinal illuminance levels: photopic, Mesopic, and scotopic levels, respectively. The spatial distance between priming and test stimuli was varied from 0 deg to 10 deg in visual angle. When the stimuli were high-contrast, the test stimulus was perceived to move in the same direction as the primer (positive priming) under photopic level, while the test stimulus was perceived to move in the opposite direction of the primer (negative priming) under scotopic level. Neither positive nor negative priming was observed under Mesopic level. When the stimuli were low-contrast and spatially separated, however, only negative priming was observed regardless of the retinal illuminance level. These results suggest that a higher-order motion system such as a feature-tracking mechanism is functioning to induce visual motion perception under photopic level, while a first-order center-surround motion system is functioning under scotopic level. We speculate that the concurrent activation of different motion mechanisms induces a degradation of motion sensitivity under Mesopic Vision

Sanae Yoshimoto - One of the best experts on this subject based on the ideXlab platform.

  • Motion perception under Mesopic Vision.
    Journal of Vision, 2016
    Co-Authors: Sanae Yoshimoto, Katsunori Okajima, Tatsuto Takeuchi
    Abstract:

    Mesopic and scotopic Vision extend over an illuminance range of 106. The goal of the present study was to determine the effect of decreasing light level on the underlying motion mechanism that integrates spatiotemporally separated motion signals. To accomplish this, we took advantage of the phenomenon of visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the directional movement of a preceding priming stimulus. After terminating a drifting priming stimulus, a 180° phase-shifted grating was presented as a test stimulus. The priming and test stimuli were separately presented to the central and peripheral retinas, respectively. The participants judged the perceived direction of this test stimulus at various light levels from photopic to scotopic levels. We found that the effects of motion priming disappeared over 1 log unit of Mesopic light levels. When the test stimulus was presented before the offset of the priming stimulus to compensate for the temporal delay in the rod pathway or when both stimuli were presented at the same location in the periphery, a motion-priming effect appeared at Mesopic light levels. These results suggest that different temporal characteristics between the cone pathway and rod pathway disturb the function of the putative motion mechanism responsible for the spatiotemporal integration of motion signals, which leads to specific modulation of motion perception over a wide range of Mesopic Vision.

  • Effect of light level on the reference frames of visual motion processing.
    Journal of Vision, 2014
    Co-Authors: Sanae Yoshimoto, Mariko Uchida-ota, Tatsuto Takeuchi
    Abstract:

    It is empirically known that some action-related visual tasks, which may rely on the construction of spatiotopic coordinates, are not well conducted under Mesopic Vision. The aim of this study was to clarify the effect of light level on the reference frame, such as retinotopic and spatiotopic coordinate bases, associated with visual motion processing. For this purpose, we used a phenomenon called visual motion priming in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a priming stimulus. Previous studies have shown that negative and positive motion priming are conspicuously observed in retinotopic and spatiotopic coordinates, respectively. In the experiments, participants made a saccade after the termination of the priming stimulus and judged the perceived direction of the test stimulus presented subsequently in retinotopic or spatiotopic coordinates at different light levels. We found that in retinotopic coordinates, negative motion priming was observed at all light levels. In spatiotopic coordinates, positive motion priming was observed at photopic and scotopic light levels, whereas the strength of motion priming was greatly reduced at Mesopic light levels. These results were robust to the change in the luminance contrast or the saccadic eye movement per se. Different spatiotemporal properties of cones and rods at Mesopic light levels may disturb the construction of a spatiotopic representation of motion, which leads to the disappearance of visual motion priming in spatiotopic coordinates during Mesopic Vision.

  • Visual motion priming reveals why motion perception deteriorates during Mesopic Vision.
    Journal of Vision, 2013
    Co-Authors: Sanae Yoshimoto, Tatsuto Takeuchi
    Abstract:

    We know empirically that the perception of moving objects deteriorates under Mesopic Vision, in which both rods and cones operate. The purpose of this study was to examine the cause of this degradation. We utilized a phenomenon called visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a preceding stimulus. The spatial distances between the priming and the test stimuli were varied. At Mesopic light levels, a stimulus that is presented at the central retina is presumably processed by the cone system, while a stimulus that is presented at the peripheral retina is processed by the rod system (Raphael & MacLeod, 2011). Subjects judged the perceived direction of 180° phase-shifted sine-wave grating that was followed by a smoothly drifting priming stimulus under different retinal illuminances. We found that, under Mesopic conditions, the strength of motion priming was greatly reduced when the priming and test stimuli were presented separately at the center and the periphery, respectively. In contrast, motion priming was perceived in most of the trials under photopic and scotopic conditions or when both the priming and test stimuli were presented at the central retina under Mesopic conditions. When the priming and test stimuli temporally overlapped, motion priming was conspicuous irrespective of the retinal illuminance. These results suggest that the incompleteness in the integration of signals that was induced by the temporal delay of rod pathways caused the degradation of motion perception under Mesopic Vision.

  • Reversal of visual motion priming under Mesopic Vision
    Japanese Journal of Psychology, 2012
    Co-Authors: Sanae Yoshimoto, Tatsuto Takeuchi
    Abstract:

    : It is known that a directionally ambiguous test stimulus is perceived to move in the same direction as a brief preceding priming stimulus when both stimuli are presented at the same retinal location (visual motion priming). To examine the spatial properties of visual motion priming under different retinal illuminance, we manipulated the distance between the priming and test stimuli. Participants judged the perceived direction of 180 deg phase-shifted, thus directionally ambiguous, sine-wave gratings (test stimulus) displayed immediately after the offset of a smoothly drifting priming stimulus. The distance between priming and test stimuli was varied from 0 to 10 deg in visual angle. Since the spatial summation area broadens under low retinal illuminance, we predicted that visual motion priming would be more conspicuous under Mesopic Vision than under photopic Vision. Contrary to this prediction, as the retinal illuminance decreased and the distance between the primer and the test stimulus increased, the test stimulus was perceived to move in the direction opposite to the priming stimulus. We speculate that different motion integration systems are functioning depending on the retinal illuminance.

  • P3-17: Why is it Difficult to See Moving Objects in the Dusk? Visual Motion Priming Reveals Two Motion Mechanisms Functioning under Mesopic Vision
    i-Perception, 2012
    Co-Authors: Sanae Yoshimoto, Tatsuto Takeuchi
    Abstract:

    We know empirically that perception of moving objects deteriorates in the dusk. The purpose of this study is to reveal the reason of such sensitivity degradation under Mesopic Vision, when both cones and rods operate. For the purpose, we utilized a phenomenon called visual motion priming, in which the perceived direction of a directionally ambiguous test stimulus is influenced by the moving direction of a preceding priming stimulus. Participants judged the perceived direction of 180 deg phase-shifted, thus directionally ambiguous, sine-wave grating (test stimulus) followed by a smoothly drifting priming stimulus under three different retinal illuminance levels: photopic, Mesopic, and scotopic levels, respectively. The spatial distance between priming and test stimuli was varied from 0 deg to 10 deg in visual angle. When the stimuli were high-contrast, the test stimulus was perceived to move in the same direction as the primer (positive priming) under photopic level, while the test stimulus was perceived to move in the opposite direction of the primer (negative priming) under scotopic level. Neither positive nor negative priming was observed under Mesopic level. When the stimuli were low-contrast and spatially separated, however, only negative priming was observed regardless of the retinal illuminance level. These results suggest that a higher-order motion system such as a feature-tracking mechanism is functioning to induce visual motion perception under photopic level, while a first-order center-surround motion system is functioning under scotopic level. We speculate that the concurrent activation of different motion mechanisms induces a degradation of motion sensitivity under Mesopic Vision

Kazufumi Kaneda - One of the best experts on this subject based on the ideXlab platform.

  • Fast Local Tone Mapping, Summed-Area Tables and Mesopic Vision Simulation
    Computer Graphics, 2012
    Co-Authors: Marcos Slomp, Michihiro Mikamo, Kazufumi Kaneda
    Abstract:

    High dynamic range (HDR) imaging is becoming an increasingly popular practice in computer graphics, bringing unprecedented levels of realism to computer-generated imagery and rich detail preservation to photographs and films. HDR imagery can embrace more accurately the wide range of light intensities found in real scenes than its counterpart, low dynamic range (LDR), which are tailored to the limited intensities of display devices. Simply put in computer terminology, think of HDR as a very large, continuous range of intensities encoded in a floating-point representation (but not necessarily), while LDR translates to coarse, quantized ranges, usually encoded as 8-bit integers and thus limited to 256 discrete intensities.

  • a tone reproduction method accounting for Mesopic Vision
    The Journal of The Institute of Image Information and Television Engineers, 2010
    Co-Authors: Michihiro Mikamo, Marcos Slomp, Toru Tamaki, Kazufumi Kaneda
    Abstract:

    Most tone reproduction operators focus on luminance compression, ignoring chromatic assets. The humanvisual system, however, alters color perception according to the overall level of luminosity. This paper proposes an extensionfor existing operators to simulate chromatic changes under Mesopic Vision. In such conditions, red responses tend to fadefaster than the remaining stimuli, producing a blue-shift phenomenon known as the Purkinje E ect. Starting with a highdynamic range image, the proposed method proceeds by separating luminance and chrominance components. Luminancecompression is performed by means of any already existing operator, though in this paper, for convenience, the photographicoperator was employed. Chromatic changes are handled in a decoupled fashion according to overall average luminance and byfollowing the observations of previous psychophysical experiments. Finally, compressed luminance and adjusted chrominanceare combined together, providing a displayable, low-dynamic range image. The technique has a low fingerprint thus beingsuitable for interactive rendering.

  • a tone reproduction operator accounting for Mesopic Vision
    International Conference on Computer Graphics and Interactive Techniques, 2009
    Co-Authors: Michihiro Mikamo, Marcos Slomp, Toru Tamaki, Kazufumi Kaneda
    Abstract:

    High dynamic range (HDR) imaging provides more physically accurate measurements of pixel intensities, but displaying them may require tone mapping as the dynamic range between image and display device can differ. Most tone-mapping operators (TMO) focus on luminance compression ignoring chromatic assets. The human visual system (HVS), however, alters color perception according to the level of luminosity. At photopic conditions color perception is accurate and as conditions shift to scotopic, color perception decreases. Mesopic Vision is a range in between where colors are perceived but in a distorted way: red intensities' responses fade faster producing a blue-shift effect known as Purkinje effect.

  • SIGGRAPH ASIA Posters - A tone reproduction operator accounting for Mesopic Vision
    ACM SIGGRAPH ASIA 2009 Posters on - SIGGRAPH ASIA '09, 2009
    Co-Authors: Michihiro Mikamo, Marcos Slomp, Toru Tamaki, Kazufumi Kaneda
    Abstract:

    High dynamic range (HDR) imaging provides more physically accurate measurements of pixel intensities, but displaying them may require tone mapping as the dynamic range between image and display device can differ. Most tone-mapping operators (TMO) focus on luminance compression ignoring chromatic assets. The human visual system (HVS), however, alters color perception according to the level of luminosity. At photopic conditions color perception is accurate and as conditions shift to scotopic, color perception decreases. Mesopic Vision is a range in between where colors are perceived but in a distorted way: red intensities' responses fade faster producing a blue-shift effect known as Purkinje effect.