Preliminary Result on the Direct Assessment of Perceptible Simultaneous Luminance Dynamic Range

Journal of Imaging Science and Technology ◽

10.2352/j.imagingsci.technol.2021.65.5.050401 ◽

2021 ◽

Author(s):

Fu Jiang ◽

Mark D. Fairchild

Keyword(s):

Visual System ◽

Dynamic Range ◽

Luminance Level ◽

Psychophysical Experiment ◽

Range Data ◽

Stimulus Luminance ◽

Wide Dynamic Range ◽

A Value ◽

Log Linear ◽

Full Adaptation

The human visual system is capable of adapting across a very wide dynamic range of luminance levels; values up to 14 log units have been reported. However, when the bright and dark areas of a scene are presented simultaneously to an observer, the bright stimulus produces significant glare in the visual system and prevents full adaptation to the dark areas, impairing the visual capability to discriminate details in the dark areas and limiting simultaneous dynamic range. Therefore, this simultaneous dynamic range will be much smaller, due to such impairment, than the successive dynamic range measurement across various levels of steady-state adaptation. Previous indirect derivations of simultaneous dynamic range have suggested between 2 and 3.5 log units. Most recently, Kunkel and Reinhard reported a value of 3.7 log units as an estimation of simultaneous dynamic range, but it was not measured directly. In this study, simultaneous dynamic range was measured directly through a psychophysical experiment. It was found that the simultaneous dynamic range is a bright-stimulus-luminance dependent value. A maximum simultaneous dynamic range was found to be approximately 3.3 log units. Based on the experimental data, a descriptive log-linear model and a nonlinear model were proposed to predict the simultaneous dynamic range as a function of stimulus size with bright-stimulus luminance-level dependent parameters. Furthermore, the effect of spatial frequency in the adapting pattern on the simultaneous dynamic range was explored. A log parabola function, representing a traditional Contrast Sensitivity Function (CSF), fitted the simultaneous dynamic range data well.

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Perceptually motivated model for predicting banding artefacts in high-dynamic range images

Color and Imaging Conference ◽

10.2352/issn.2169-2629.2020.28.8 ◽

2020 ◽

Vol 2020 (28) ◽

pp. 42-48

Author(s):

Minjung Kim ◽

Maryam Azimi ◽

Rafał K. Mantiuk

Keyword(s):

Visual System ◽

Contrast Sensitivity ◽

Dynamic Range ◽

High Dynamic Range ◽

Sensitivity Function ◽

Psychophysical Experiment ◽

Texture Region ◽

Wide Range ◽

Artefact Detection ◽

High Dynamic

Banding is a type of quantisation artefact that appears when a low-texture region of an image is coded with insufficient bitdepth. Banding artefacts are well-studied for standard dynamic range (SDR), but are not well-understood for high dynamic range (HDR). To address this issue, we conducted a psychophysical experiment to characterise how well human observers see banding artefacts across a wide range of luminances (0.1 cd/m2–10,000 cd/m2). The stimuli were gradients modulated along three colour directions: black-white, red-green, and yellow-violet. The visibility threshold for banding artefacts was the highest at 0.1 cd/m2, decreased with increasing luminance up to 100 cd/m2, then remained at the same level up to 10,000 cd/m2. We used the results to develop and validate a model of banding artefact detection. The model relies on the contrast sensitivity function (CSF) of the visual system, and hence, predicts the visibility of banding artefacts in a perceptually accurate way.

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Selection Methodology of A/D Converters for a Wide Dynamic Range Data Acquisition System

2007 IEEE Region 5 Technical Conference ◽

10.1109/tpsd.2007.4380404 ◽

2007 ◽

Author(s):

Bijoy Chatt

Keyword(s):

Data Acquisition ◽

Dynamic Range ◽

Data Acquisition System ◽

Acquisition System ◽

Range Data ◽

Wide Dynamic Range ◽

Selection Methodology

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Slow-Scan CCD Observation of Backscattering Patterns in SEM

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100131176 ◽

1992 ◽

Vol 50 (2) ◽

pp. 1308-1309

Author(s):

F. Ouyang ◽

D. A. Ray ◽

O. L. Krivanek

Keyword(s):

Electron Beam ◽

Electron Microscope ◽

Scanning Electron Microscope ◽

Dynamic Range ◽

High Sensitivity ◽

Lens System ◽

Wide Dynamic Range ◽

Peltier Cooler ◽

Diffraction Patterns ◽

Scanning Electron

Electron backscattering Kikuchi diffraction patterns (BKDP) reveal useful information about the structure and orientation of crystals under study. With the well focused electron beam in a scanning electron microscope (SEM), one can use BKDP as a microanalysis tool. BKDPs have been recorded in SEMs using a phosphor screen coupled to an intensified TV camera through a lens system, and by photographic negatives. With the development of fiber-optically coupled slow scan CCD (SSC) cameras for electron beam imaging, one can take advantage of their high sensitivity and wide dynamic range for observing BKDP in SEM.We have used the Gatan 690 SSC camera to observe backscattering patterns in a JEOL JSM-840A SEM. The CCD sensor has an active area of 13.25 mm × 8.83 mm and 576 × 384 pixels. The camera head, which consists of a single crystal YAG scintillator fiber optically coupled to the CCD chip, is located inside the SEM specimen chamber. The whole camera head is cooled to about -30°C by a Peltier cooler, which permits long integration times (up to 100 seconds).

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Effects of Black Luminance Level on Image Quality

Color and Imaging Conference ◽

10.2352/issn.2169-2629.2019.27.20 ◽

2019 ◽

Vol 2019 (1) ◽

pp. 104-107

Author(s):

Ye Seul Baek ◽

Youngshin Kwak ◽

Sehyeok Park

Keyword(s):

Image Quality ◽

Luminance Level ◽

Psychophysical Experiment ◽

Image Histogram ◽

Affect Image Quality ◽

Low Luminance ◽

Black Level ◽

Oled Display ◽

Dark Room

The image quality is affected by the black luminance level of the image. This research aimed to investigate how low luminance levels are required to maintain image quality. The psychophysical experiment was carried out in a dark room using OLED display. Total of 6 different black luminance levels (0.003, 0.05, 0.1, 0.2, 0.3, and 1 cd/m2) were used in the experiment. Total of 20 participants was invited to evaluate the image quality. For the experiment, twelve test images are used and these test images categorized into three groups as dark, medium bright and bright image group by image histogram distribution. Each image is rendered by adjusting six different black luminance levels. Result found that the black level is higher than 0.1 cd/m2, the preference for the image is decreased. The best performance is achieved when the black level is 0.003 cd/m2, but there is no big difference from 0.1 cd/m2. The final result shows that a change in black level between about 0.003 cd/m2 and 0.1 cd/m2 does not significantly affect image quality.

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Evaluation of the Human Visual System in Cosmetics Foundation Colour Selection

London Imaging Meeting ◽

10.2352/issn.2694-118x.2020.lim-22 ◽

2020 ◽

Vol 2020 (1) ◽

pp. 60-64

Author(s):

Altynay Kadyrova ◽

Majid Ansari-Asl ◽

Eva Maria Valero Benito

Keyword(s):

Visual System ◽

Human Visual System ◽

Skin Tone ◽

Skin Colour ◽

Psychophysical Experiment ◽

Spectral Measurements ◽

Practical Applications ◽

Subjective Evaluations ◽

Colour Measurements ◽

Colour Quantification

Colour is one of the most important appearance attributes in a variety of fields including both science and industry. The focus of this work is on cosmetics field and specifically on the performance of the human visual system on the selection of foundation makeup colour that best matches with the human skin colour. In many cases, colour evaluations tend to be subjective and vary from person to person thereby producing challenging problems to quantify colour for objective evaluations and measurements. Although many researches have been done on colour quantification in last few decades, to the best of our knowledge, this is the first study to evaluate objectively a consumer's visual system in skin colour matching through a psychophysical experiment under different illuminations exploiting spectral measurements. In this paper, the experiment setup is discussed and the results from the experiment are presented. The correlation between observers' skin colour evaluations by using PANTONE Skin Tone Guide samples and spectroradiometer is assessed. Moreover, inter and intra observer variability are considered and commented. The results reveal differences between nine ethnic groups, between two genders, and between the measurements under two illuminants (i.e.D65 and F (fluorescent)). The results further show that skin colour assessment was done better under D65 than under F illuminant. The human visual system was three times worse than instrument in colour matching in terms of colour difference between skin and PANTONE Skin Tone Guide samples. The observers tend to choose lighter, less reddish, and consequently paler colours as the best match to their skin colour. These results have practical applications. They can be used to design, for example, an application for foundation colour selection based on correlation between colour measurements and human visual system based subjective evaluations.

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