scholarly journals Scaling and discriminability of perceived gloss

2020 ◽  
Author(s):  
Jacob Raleigh Cheeseman ◽  
James A. Ferwerda ◽  
Frank J. Maile ◽  
Roland Fleming
Keyword(s):  
Maximum Likelihood ◽  
Visual Sensitivity ◽  
Surface Reflectance ◽  
Natural Illumination ◽  
Specular Reflectance ◽  
Reflectance Model ◽  
Perceptual Scale ◽  
Method Of Constant Stimuli

While much attention has been given to understanding biases in gloss perception (e.g., changes in perceived reflectance as a function of lighting, shape, viewpoint and other factors), here we investigated sensitivity to changes in surface reflectance. We tested how visual sensitivity to differences in specular reflectance varies as a function of the magnitude of specular reflectance. Stimuli consisted of renderings of glossy objects under natural illumination. Using Maximum Likelihood Difference Scaling, we created a perceptual scaling of the specular reflectance parameter of the Ward reflectance model. Then, using the Method of Constant Stimuli and a standard 2AFC procedure, we obtained psychometric functions for gloss discrimination across a range of reflectance values derived from the perceptual scale. Both methods demonstrate that discriminability is significantly diminished at high levels of specular reflectance, suggesting that gloss sensitivity depends on the magnitude of change in the image produced by different reflectance values.

scholarly journals Evaluation of the MERIS aerosol product over land with AERONET

2008 ◽  
Vol 8 (1) ◽  
pp. 3721-3759 ◽  
Author(s):  
J. Vidot ◽  
R. Santer ◽  
O. Aznay
Keyword(s):  
Optical Properties ◽  
Surface Reflectance ◽  
Aerosol Optical Properties ◽  
Simple Criterion ◽  
Imaging Spectrometer ◽  
Inherent Optical Properties ◽  
Look Up Table ◽  
Medium Resolution ◽  
Reflectance Model ◽  
Resolution Imaging

Abstract. The Medium Resolution Imaging Spectrometer (MERIS) launched in February 2002 on-board the ENVISAT spacecraft is making global observations of top-of-atmosphere (TOA) radiances. Aerosol optical properties are retrieved over land using Look-Up Table (LUT) based algorithm and surface reflectances in the blue and the red spectral regions. We compared instantaneous aerosol optical thicknesses retrieved by MERIS in the blue and the red at locations containing sites within the Aerosol Robotic Network (AERONET). Between 2002 and 2005, a set of 500 MERIS images were used in this study. The result shows that, over land, MERIS aerosol optical thicknesses are well retrieved in the blue and poorly retrieved in the red, leading to an underestimation of the Angstrom coefficient. Correlations are improved by applying a simple criterion to avoid scenes probably contaminated by thin clouds. To investigate the weakness of the MERIS algorithm, ground-based radiometer measurements have been used in order to retrieve new aerosol models, based on their Inherent Optical Properties (IOP). These new aerosol models slightly improve the correlation, but the main problem of the MERIS aerosol product over land can be attributed to the surface reflectance model in the red.

On-orbit vicarious calibration of ocean color sensors using an ocean surface reflectance model

2007 ◽  
Vol 46 (23) ◽  
pp. 5649 ◽  
Author(s):  
P. Jeremy Werdell ◽  
Sean W. Bailey ◽  
Bryan A. Franz ◽  
André Morel ◽  
Charles R. McClain
Keyword(s):  
Ocean Color ◽  
Ocean Surface ◽  
Surface Reflectance ◽  
Vicarious Calibration ◽  
Reflectance Model ◽  
Color Sensors

scholarly journals Suprathreshold contrast response in normal and anomalous trichromats

2019 ◽  
Author(s):  
Kenneth Knoblauch ◽  
Brennan Marsh-Armstrong ◽  
John S. Werner
Keyword(s):  
Maximum Likelihood ◽  
Low Frequency ◽  
Luminance Contrast ◽  
Contrast Gain ◽  
Detection Model ◽  
Response Range ◽  
The Difference ◽  
Contrast Response ◽  
Contrast Range ◽  
Perceptual Scale

AbstractMaximum Likelihood Difference Scaling was used to measure suprathreshold contrast response difference scales for low-frequency Gabor patterns modulated along luminance and L-M color directions in normal, protanomalous, and deuteranomalous observers. Based on a signal-detection model, perceptual scale values, parameterized as d′, were estimated by maximum likelihood. The difference scales were well fit by a Michaelis-Menten model, permitting estimates of response and contrast gain parameters for each subject. Anomalous observers showed no significant differences in response or contrast gain from normal observers for luminance contrast. For chromatic modulations, however, anomalous observers displayed higher contrast and lower response gain compared to normal observers. These effects cannot be explained by simple pigment shift models and support a compensation mechanism to optimize the mapping of the input contrast range to the neural response range. A linear relation between response and contrast gain suggests a neural trade-off between them.

A surface reflectance model for aerosol remote sensing over land

2007 ◽  
Vol 28 (3-4) ◽  
pp. 737-760 ◽  
Author(s):  
R. Santer ◽  
D. Ramon ◽  
J. Vidot ◽  
E. Dilligeard
Keyword(s):  
Remote Sensing ◽  
Surface Reflectance ◽  
Reflectance Model ◽  
Aerosol Remote Sensing

scholarly journals Surface reflectance estimation under unknown natural illumination

2010 ◽  
Vol 1 (3) ◽  
pp. 43-43 ◽  
Author(s):  
R. W. Fleming ◽  
R. O. Dror ◽  
E. H. Adelson
Keyword(s):  
Surface Reflectance ◽  
Natural Illumination
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