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

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.

scholarly journals Contrast Sensitivity Based Multiscale Base–Detail Separation for Enhanced HDR Imaging

2020 ◽  
Vol 10 (7) ◽  
pp. 2513 ◽  
Author(s):  
Hyuk-Ju Kwon ◽  
Sung-Hak Lee
Keyword(s):  
Image Quality ◽  
Contrast Sensitivity ◽  
Human Visual System ◽  
Dynamic Range ◽  
Bilateral Filter ◽  
High Dynamic Range ◽  
Sensitivity Function ◽  
Base Layer ◽  
Compensation Technique ◽  
High Dynamic

High dynamic range (HDR) imaging is used to represent scenes with a greater dynamic range of luminance on a standard dynamic range display. Usually, HDR images are synthesized through base–detail separations. The base layer is used for tone compression and the detail layer is used for detail preservation. The representative detail-preserved algorithm iCAM06 has a tendency to reduce the sharpness of dim surround images, because of the fixed edge-stopping function of the fast-bilateral filter (FBF). This paper proposes a novel base–detail separation and detail compensation technique using the contrast sensitivity function (CSF) in the segmented frequency domain. Experimental results show that the proposed rendering method has better sharpness features and image quality than previous methods correlated by the human visual system.

Product Review: High Dynamic Range Displays

2007 ◽  
Vol 16 (1) ◽  
pp. 119-122 ◽  
Author(s):  
Patrick Ledda
Keyword(s):  
Dynamic Range ◽  
Liquid Crystal Display ◽  
Contrast Ratio ◽  
Luminance Level ◽  
High Dynamic Range ◽  
Natural World ◽  
Adaptation Level ◽  
Wide Range ◽  
High Dynamic ◽  
3D Software

In the natural world, the human eye is confronted with a wide range of colors and luminances. A surface lit by moonlight might have a luminance level of around 10−3 cd/m2, while surfaces lit during a sunny day could reach values larger than 105 cd/m2. A good quality CRT (cathode ray tube) or LCD (liquid crystal display) monitor is only able to achieve a maximum luminance of around 200 to 300 cd/m2 and a contrast ratio of not more than two orders of magnitude. In this context the contrast ratio or dynamic range is defined as the ratio of the highest to the lowest luminance. We call high dynamic range (HDR) images, those images (or scenes) in which the contrast ratio is larger than what a display can reproduce. In practice, any scene that contains some sort of light source and shadows is HDR. The main problem with HDR images is that they cannot be displayed, therefore although methods to create them do exist (by taking multiple photographs at different exposure times or using computer graphics 3D software for example) it is not possible to see both bright and dark areas simultaneously. (See Figure 1.) There is data that suggests that our eyes can see detail at any given adaptation level within a contrast of 10,000:1 between the brightest and darkest regions of a scene. Therefore an ideal display should be able to reproduce this range. In this review, we present two high dynamic range displays developed by Brightside Technologies (formerly Sunnybrook Technologies) which are capable, for the first time, of linearly displaying high contrast images. These displays are of great use for both researchers in the vision/graphics/VR/medical fields as well as professionals in the VFX/gaming/architectural industry.

Human Visual System-Based Saliency Detection for High Dynamic Range Content

2016 ◽  
Vol 18 (4) ◽  
pp. 549-562 ◽  
Author(s):  
Yuanyuan Dong ◽  
Mahsa T. Pourazad ◽  
Panos Nasiopoulos
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Dynamic Range ◽  
Saliency Detection ◽  
High Dynamic Range ◽  
High Dynamic

scholarly journals Spatio-chromatic contrast sensitivity across the life span: interactions between age and light level in high dynamic range

2020 ◽  
Vol 20 (11) ◽  
pp. 1286
Author(s):  
Maliha Ashraf ◽  
Sophie Wuerger ◽  
Minjung Kim ◽  
Helen Saunderson ◽  
Jasna Martinovic ◽  
...  
Keyword(s):  
Life Span ◽  
Contrast Sensitivity ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Light Level ◽  
Chromatic Contrast ◽  
High Dynamic ◽  
Chromatic Contrast Sensitivity

scholarly journals Practical Color Contrast Sensitivity Functions for Luminance Levels up to 10000 cd/m2

2020 ◽  
Vol 2020 (28) ◽  
pp. 1-6
Author(s):  
Rafał K. Mantiuk ◽  
Minjung Kim ◽  
Maliha Ashraf ◽  
Qiang Xu ◽  
M. Ronnier Luo ◽  
...  
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Range ◽  
Color Space ◽  
High Dynamic Range ◽  
Model Parameters ◽  
Color Contrast ◽  
Sensitivity Functions ◽  
Spatial Frequencies ◽  
Wide Range ◽  
Opponent Color

We model color contrast sensitivity for Gabor patches as a function of spatial frequency, luminance and chromacity of the background, modulation direction in the color space and stimulus size. To fit the model parameters, we combine the data from five independent datasets, which let us make predictions for background luminance levels between 0.0002 cd/m2 and 10 000 cd/m2, and for spatial frequencies between 0.06 cpd and 32 cpd. The data are well-explained by two models: a model that encodes cone contrast and a model that encodes postreceptoral, opponent-color contrast. Our intention is to create practical models, which can well explain the detection performance for natural viewing in a wide range of conditions. As our models are fitted to the data spanning very large range of luminance, they can find applications in modeling visual performance for high dynamic range and augmented reality displays.

A new corresponding color dataset covering a wide luminance range under high dynamic range viewing condition

2021 ◽  
Vol 2021 (29) ◽  
pp. 184-187
Author(s):  
Shi Xinye ◽  
Zhu Yuechen ◽  
Ming Ronnier Luo
Keyword(s):  
Dynamic Range ◽  
High Dynamic Range ◽  
Color Appearance ◽  
Appearance Model ◽  
Viewing Condition ◽  
Color Changes ◽  
Wide Range ◽  
Illuminance Level ◽  
High Dynamic ◽  
The Relationship

An experiment was carried out to investigate the change of color appearance for 13 surface stimuli viewed under a wide range of illuminance levels (15-32000 lux) using asymmetrical matching method. Addition to the above, in the visual field, observers viewed colours in a dark (10 lux) and a bright (200000 lux) illuminance level at the same time to simulate HDR viewing condition. The results were used to understand the relationship between the color changes under HDR conditions, to generate a corresponding color dataset and to verify color appearance model, such as CIECAM16.

Creating high fidelity 360° virtual reality with high dynamic range spherical panorama images

2019 ◽  
Vol 9 (1) ◽  
pp. 73-109
Author(s):  
Zi Siang See ◽  
Lizbeth Goodman ◽  
Craig Hight ◽  
Mohd Shahrizal Sunar ◽  
Arindam Dey ◽  
...  
Keyword(s):  
Virtual Reality ◽  
Best Practice ◽  
User Study ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
High Fidelity ◽  
Image Reproduction ◽  
Wide Range ◽  
High Dynamic ◽  
Spherical Panorama

Abstract This research explores the development of a novel method and apparatus for creating spherical panoramas enhanced with high dynamic range (HDR) for high fidelity Virtual Reality 360 degree (VR360) user experiences. A VR360 interactive panorama presentation using spherical panoramas can provide virtual interactivity and wider viewing coverage; with three degrees of freedom, users can look around in multiple directions within the VR360 experiences, gaining the sense of being in control of their own engagement. This degree of freedom is facilitated by the use of mobile displays or head-mount-devices. However, in terms of image reproduction, the exposure range can be a major difficulty in reproducing a high contrast real-world scene. Imaging variables caused by difficulties and obstacles can occur during the production process of spherical panorama facilitated with HDR. This may result in inaccurate image reproduction for location-based subjects, which will in turn result in a poor VR360 user experience. In this article we describe a HDR spherical panorama reproduction approach (workflow and best practice) which can shorten the production processes, and reduce imaging variables, and technical obstacles and issues to a minimum. This leads to improved photographic image reproduction with fewer visual abnormalities for VR360 experiences, which can be adaptable into a wide range of interactive design applications. We describe the process in detail and also report on a user study that shows the proposed approach creates images which viewers prefer, on the whole, to those created using more complicated HDR methods, or to those created without the use of HDR at all.

scholarly journals Human visual system inspired saliency guided edge preserving tone-mapping for high dynamic range imaging

2021 ◽  
Author(s):  
Nipu Rani Barai
Keyword(s):  
Visual System ◽  
Human Visual System ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Guided Filter ◽  
Tone Mapping ◽  
High Dynamic Range Imaging ◽  
Range Imaging ◽  
Edge Preserving ◽  
High Dynamic

With the growing popularity of High Dynamic Range Imaging (HDRI), the necessity for advanced tone-mapping techniques has greatly increased. In this thesis, I propose a novel saliency guided edge-preserving tone-mapping method that uses saliency region information of an HDR image as input to a guided filter for base and detail image layer separation. Both high resolution and low resolution saliency maps were used for the performance evaluation of the proposed method. After detail layer enhancement and base layer compression with constant weights, a new edge preserved tone-mapped image was composed by adding the layers back together with saturation and exposure adjustments. The filter operation is faster due to the use of the guided filter, which has O(N) time operation with N number of pixels. Both objective and subjective quality assessment results demonstrated that the proposed method has higher edge and naturalness preserving capability, which is homologous to the Human Visual System (HVS), as compared to other state-of-the-art tone-mapping approaches.

scholarly journals Spatio-chromatic contrast sensitivity across the lifespan: interactions between age and light level in high dynamic range

2020 ◽  
Vol 2020 (28) ◽  
pp. 65-69
Author(s):  
Maliha Ashraf ◽  
Sophie Wuerger ◽  
Minjung Kim ◽  
Jasna Martinovic ◽  
Rafał K. Mantiuk
Keyword(s):  
Contrast Sensitivity ◽  
Dynamic Range ◽  
High Dynamic Range ◽  
Light Level ◽  
Background Luminance ◽  
Age Group ◽  
Chromatic Contrast ◽  
Achromatic Contrast ◽  
High Dynamic ◽  
Chromatic Contrast Sensitivity

We investigated spatio-chromatic contrast sensitivity in both younger and older color-normal observers. We tested how the adapting light level affected the contrast sensitivity and whether there was a differential age-related change in sensitivity. Contrast sensitivity was measured along three directions in colour space (achromatic, red-green, yellowish-violet), at background luminance levels from 0.02 to 2000 cd/m2, and different stimuli sizes using 4AFC method on a high dynamic range display. 20 observers with a mean age of 33 y. o. a. and 20 older observers with mean age of 65 participated in the study. Within each session, observers were fully adapted to the fixed background luminance. Our main findings are: (1) Contrast sensitivity increases with background luminance up to around 200 cd/m2, then either declines in case of achromatic contrast sensitivity, or remains constant in case of chromatic contrast sensitivity; (2) The sensitivity of the younger age group is higher than that for the older age group by 0.3 log units on average. Only for the achromatic contrast sensitivity, the old age group shows a relatively larger decline in sensitivity for medium to high spatial frequencies at high photopic light levels; (3) Peak frequency, peak sensitivity and cut-off frequency of contrast sensitivity functions show decreasing trends with age and the rate of this decrease is dependent on mean luminance. The data is being modeled to predict contrast sensitivity as a function of age, luminance level, spatial frequency, and stimulus size.

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