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Crossmodal correspondences are spontaneous associations of non-redundant information across different modalities. Infants and some non-human animals (i.e., chimpanzees, rhesus monkeys, and dogs) showed crossmodal correspondences like adult humans, suggesting a shared origin (at least among mammals) of such a phenomenon. Here we investigate visual-spatial crossmodal correspondences in a precocial avian species, i.e., the domestic chicken. Three-day-old chicks (n = 40) were presented with two (one in the left and one in the right hemispace of an arena) identical panels, either dyed black (low luminance) or white (high luminance). Chicks could circumnavigate either panel to obtain a food reward. Akin to humans, they preferentially chose the left side when presented with black panels and the right side when presented with white panels. The control group (n = 39), tested with grey panels, showed no spatial preference. In light of our results, we discuss crossmodal correspondences in terms of an early available mechanism widespread across different species. [ABSTRACT FROM AUTHOR]

In this study we investigated under what conditions motion direction changes pop out in continuously moving target/distractor environments. Participants were presented with vertically oriented Gabor patches whose carrier components drifted at a constant speed from left to right and then reversed direction. On any given trial, one of these elements was nominated as the target and the remaining elements were distractors. Distractor elements all changed direction simultaneously. The distractors either moved in a homogeneous manner (i.e. all moved in the same direction), or in a heterogeneous manner (i.e. direction was randomized). The target moved with a similar spatio-temporal trajectory as the distractors from left to right (or vice versa), but changed direction asynchronously with respect to the distracting elements. The participants' task was to locate this deviant (target) Gabor patch. We show that a motion direction change pops out (as indicated by the absence of a set size effect) when the surrounding distractors move in a homogeneous direction. When the distractors moved in heterogenous directions, a similar pop out effect was observed when the set size was small (≤5 elements), but not when it was large. This suggests that motion direction changes capture attention only when the change results in a unique direction of motion. Consistent with this finding we also show that a moving target (without direction change) captures attention in cases in which all distractors recently changed direction. This corroborates the idea that, in addition to direction cues, the temporal uniqueness of a change in an object's direction (or absence, thereof) relative to surrounding objects is a cue capable of capturing attention. [ABSTRACT FROM AUTHOR]

Generally, the more channels are used to acquire EEG signals, the better the performance of the brain-computer interface (BCI). However, from the user's point of view, a BCI system comprising a large number of channels is not desirable because of the lower comfort and extended application time. Therefore, the current trend in BCI design is to use the smallest number of channels possible. The problem is, however, that usually when we decrease the number of channels, the interface accuracy also drops significantly. In the paper, we examined whether it is possible to maintain the high accuracy of a BCI based on steady-state visual evoked potentials (SSVEP-BCI) in a low-channel setup using a preprocessing procedure successfully used in a multichannel setting: independent component analysis (ICA). The influence of ICA on the BCI performance was measured in an off-line (24 subjects) mode and online (eight subjects) mode. In the off-line mode, we compared the number of correctly recognized different stimulation frequencies, and in the online mode, we compared the classification accuracy. In both experiments, we noted the predominance of signals that underwent ICA preprocessing. In the off-line mode, we detected 50% more stimulation frequencies after ICA preprocessing than before (in the case of four EEG channels), and in the online mode, we noted a classification accuracy increase of 8%. The most important results, however, were the results obtained for a very low luminance (350 lx), where we noted 71% gain in the off-line mode and 11% gain in the online mode. [ABSTRACT FROM AUTHOR]

Highlights • Adaptive transfer function based on perceptual quantizer. • Adaptively maps luminance to luma according to HDR contents. • Good perceptual uniformity in the luminance range. • HDR video coding with HEVC Main 10 Profile. Abstract Although high dynamic range (HDR) videos are a very fascinating way to represent real-world scenes, they need a huge amount of memory to store and transmit due to the high bit-depth. Thus, it is a major challenge for HDR video coding to efficiently compress them without sacrificing perceptual quality. Perceptual Quantizer (PQ) transfer function provides a solution to this problem, which is adopted as the HEVC Main 10 Profile-based Anchor. However, PQ is not adaptive to HDR contents, thus reducing the coding efficiency. In this paper, we propose adaptive transfer function based on PQ for HDR video compression, called adaptive PQ. Different from PQ which uses a fixed mapping curve from luminance to luma, the proposed transfer function adaptively maps luminance to luma according to HDR contents. Thus, adaptive PQ is able to efficiently utilize possible luma values. Moreover, adaptive PQ achieves better perceptual uniformity in the luminance range than PQ. Experimental results demonstrate that adaptive PQ achieves a significant performance improvement in HDR video coding over PQ in terms of visual quality and bitrate. [ABSTRACT FROM AUTHOR]

A novel ghost-free exposure fusion method for generating an HDR image of a dynamic scene is presented in this paper. Given a sequence of input images with gradually increased exposures, due to the theory that the luminance is linearly depended on the exposure time (Mertens et al. Comput Graph Forum 28(1):161-171, 2009), each input image is normalized to make it have consistent luminance with a reference image. Then moving objects in the dynamic scene are detected using a modified difference method for further exposure fusion. Experiments and comparisons show that our method has advantage in deghosting when the reference image contains saturated regions and generate high-quality results with natural textures. Furthermore, our method has a largely improved timing performance compared with previous reference-guided methods. [ABSTRACT FROM AUTHOR]

We consider the chromaticity in high dynamic range (HDR) video coding and show the advantages of a constant luminance color space for encoding. For this, we introduce two constant luminance HDR video coding pipelines, which convert the source video to linear $Y u^\prime v^\prime $. A content dependent scaling of the chromaticity components serves as color quality parameter. This reduces perceivable color artifacts while remaining fully compatible with core High Efficiency Video Coding or other video coding standards. One of the pipelines further combines the scaling with a dedicated chromaticity transform to optimize the representation of the chromaticity components for encoding. We validate both pipelines with subjective user studies in addition to an objective comparison to the other state-of-the-art methods. The user studies show a significant improvement in perceived color quality at medium to high compression rates without sacrificing luminance quality compared with current standard coding pipelines. The objective evaluation suggests that both pipelines perform at least comparable to the current state-of-the-art methods. [ABSTRACT FROM AUTHOR]

We propose a saturation-aware human attention region-of-interest (SA-HAROI) video compression method that performs a perceptual adaptive quantization algorithm on video frames as a function of the distribution of their luminance, motion vector, and color saturation. Our work is an application of a psycho-visual study that demonstrated that human attention automatically enhanced perceived saturation. Consequently, the adaptive quantization phase of our compression algorithm is characterized by a luminance and saturation-aware just noticeable distortion (JND) function. After running multiple experiments on 18 videos with various resolutions ranging from QCIF to 4 K, results showed that our method achieves higher compression than that of both the H.264/AVC JM and the HEVC HM while maintaining subjective quality. We observed that in comparison to both implementation of the standards (JM and HM), for an IPPP coding structure, the performance of our algorithm culminated with HD and 4 K videos yielding a bit rate reduction averaging 15% and an encoding time reduction of about 20% in certain cases. Finally, after comparing our method to other similar techniques, we concluded that saturation is a significant parameter in the improvement of video compression. [ABSTRACT FROM AUTHOR]

This paper describes a 4K/60p high efficiency video coding (HEVC, the latest coding standard) real-time encoding system with high quality high dynamic range (HDR) color representations. The HDR technology provides attractive video contents with a wider dynamic range of luminance, which can make shadows and brighter details appear clearly without any blown out highlights or blocked up shadows. We propose a new rate control method for HDR video coding. The method consists of two algorithms for improving perceptual quality by reducing degradation of HDR-specific color artifacts. The first one, adaptive block size and prediction mode decision, is conducted to suppress perceptual degradation due to prediction error in high chroma areas. The second, local quantization parameter control, is carried out to improve the visual quality with appropriate bit allocation in low chroma areas. The method was implemented in an HEVC real-time encoding system and its performance was assessed by measuring the color difference metrics by 3.86% at the most degraded frame, while peak signal-to-noise ratio remained almost the same. The subjective quality of the decoded HDR images was improved by reducing color artifacts. [ABSTRACT FROM AUTHOR]

Up to now, a number of tone mapping methods have been proposed through a lot of literatures to reduce halos and to overcome loss of detailed information in a given high dynamic range image (HDRI) while reproducing colors. In these efforts, there are a wide variety of tone mapping techniques including global tone mapping technique, local tone mapping technique, and a combination of both techniques. However, there are still unsolved challenges such as halos, loss of detailed information, and color distortion like luminance shift and hue shift in the consequence of performing the conventional tone mapping methods. Accordingly, this article presents a novel approach to solving these problems by combining the modified guided filter method and the Total Variation (TV)-based restoration model, thereby comprising the proposed tone mapping operator. The main purpose of combining both is to decompose the HDRI into the base layer (illumination components) and the detail layer (reflectance components), which offers several advantages: removing noise and representing detailed information in resulting images. Adaptive gamma correction is also adopted to effectively reduce luminance shift and hue shift by automatically controlling the dynamic range, parameter free. The chromatic adaptation transform is then used to address the mismatch between displayed images and real-life scenes based on the human visual perception (HVP). The main contribution of the proposed approach is to overcome halos and loss of detailed information arising from the local tone mapping technique or the global tone mapping one. The experimental results show that the proposed tone mapping method yields better performance over the conventional method in subjective and quantitative qualities and color reproduction. [ABSTRACT FROM AUTHOR]

Highlights • Subjects who had training to play a musical instrument significantly outperformed their untrained counterparts in detecting repetitions within rapidly presented sequences. • This advantage held for auditory and visual sequences. • Reverse correlation revealed that subjects' reliance on different items in a sequence was altered by the presence of a correlated, concurrent auditory stream. • Congruence of auditory and visual items improved performance more than predicted from simple summation of information from each of the two modalities. Abstract Demonstrated interactions between seeing and hearing led us to assess the link between music training and short-term memory for auditory, visual and audiovisual sequences of rapidly presented, quasi-random components. Visual sequences' components varied in luminance; auditory sequences' components varied in frequency. Concurrent components in audiovisual sequences were either congruent (the frequency of an auditory item increased monotonically with the luminance of the visual item it accompanied), or incongruent (an item's frequency was uncorrelated with luminance of the item it accompanied). Subjects judged whether the last four items in a sequence replicated its first four items. With audiovisual sequences, subjects were instructed to ignore the sequence's auditory components, basing their judgments solely on the visual input. Subjects with prior instrumental training significantly outperformed their untrained counterparts, with both auditory and visual sequences, and with sequences of correlated auditory and visual items. Reverse correlation showed that the presence of a correlated, concurrent auditory stream altered subjects' reliance on particular visual items in a sequence. Moreover, congruence between auditory and visual items produced performance above what would be predicted from simple summation of information from the two modalities, a result that might reflect a contribution from special-purpose, multimodal neural mechanisms. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • A no-reference image quality assessment method is proposed. • The method extracts local features from high-order derivatives of color channels. • Statistics of pixel blocks are used to train a quality model. • Experimental results on six image datasets reveal the effectiveness of the method. Abstract The perceptual quality of images is often affected by applied image processing techniques. Their evaluation requires tests which involve human subjects. However, in most cases, image quality assessment (IQA) should be automatic and reproducible. Therefore, in this paper, a novel no-reference IQA method is proposed. The method uses high-order derivatives to extract detailed structure deformation present in distorted images. Furthermore, it employs local features, considering that only some regions of an image carry interesting information. Then, statistics of local features are used by a support vector regression technique to provide an objective quality score. To improve the quality prediction, luminance and chrominance channels of the image are processed. Experimental results on six large-scale public IQA image datasets show that the proposed method outperforms the state-of-the-art hand-crafted and deep-learning techniques in terms of the visual quality prediction accuracy. Furthermore, the method is better than popular full-reference approaches (i.e., SSIM and PSNR). [ABSTRACT FROM AUTHOR]

Highlights • Just noticeable difference (JND) increases when viewing depth increase in the VR environment. • Considering depth effect on visibility threshold can add more unperceived noises in images. • Foveation effect that JND increases with eccentricity is also observed in the VR environment. Abstract In this paper, we develop a joint foveation-depth just-noticeable-difference (FD-JND) model to quantify the perceptual redundancy of image in the VR display environment. The proposed FD-JND model is developed with considerations on the effects of both foveation and depth. More specifically, experiments for the VR environment on synthesized stimuli are conducted based on luminance masking and contrast masking and the FD-JND model is developed accordingly. Subjective quality discrimination experiments between the noise contaminated images and original ones validate favorableness of the proposed FD-JND model. [ABSTRACT FROM AUTHOR]

As an emissive display, the active matrix organic light-emitting diodes (AMOLEDs) endure lower power efficiency at the higher level of pixel intensities. In the existing techniques, the power consumption is lowered with a significant loss of details and hue alterations. This paper proposes a hue-preserving pixel-dimming technique using subtractive coefficients based on the decomposed hue–saturation–value color map that reduces the power consumption on AMOLED displays. An entropy-based scene detection is adopted to maintain the computational efficiency of the proposed method on video input. Experimental results on a 5.5-in 1080p AMOLED displays show that the proposed method conserves up to 73% of the displaying power with high perceptual qualities as compared with the existing methods. [ABSTRACT FROM AUTHOR]

In multimedia transmission, it is important to rely on an objective quality metric which accurately represents the subjective quality of processed images and video sequences. Maintaining acceptable Quality of Experience in video transmission requires the ability to measure the quality of the video seen at the receiver end. Reduced-reference metrics make use of side-information that is transmitted to the receiver for estimating the quality of the received sequence with low complexity. This attribute enables real-time assessment and visual degradation detection caused by transmission and compression errors. A novel reduced-reference video quality known as the Spatial Information in Salient Regions Reduced Reference Metric is proposed. The approach proposed makes use of spatial activity to estimate the received sequence distortion after concealment. The statistical elements analysed in this work are based on extracted edges and their luminance distributions. Results highlight that the proposed edge dissimilarit y measure has a good correlation with DMOS scores from the LIVE Video Database. [ABSTRACT FROM AUTHOR]

We propose a system to infer binocular disparity from a monocular video stream in real-time. Different from classic reconstruction of physical depth in computer vision, we compute perceptually plausible disparity, that is numerically inaccurate, but results in a very similar overall depth impression with plausible overall layout, sharp edges, fine details and agreement between luminance and disparity. We use several simple monocular cues to estimate disparity maps and confidence maps of low spatial and temporal resolution in real-time. These are complemented by spatially-varying, appearance-dependent and class-specific disparity prior maps, learned from example stereo images. Scene classification selects this prior at runtime. Fusion of prior and cues is done by means of robust MAP inference on a dense spatio-temporal conditional random field with high spatial and temporal resolution. Using normal distributions allows this in constant-time, parallel per-pixel work. We compare our approach to previous 2D-to-3D conversion systems in terms of different metrics, as well as a user study and validate our notion of perceptually plausible disparity. [ABSTRACT FROM PUBLISHER]

Retrieving the most relevant video frames that contain the object specified in a given query (query-by-region) remains a challenging task. Two common challenges of region-based retrieval approaches are to accurately extract or segment object(s) and select a proper matching strategy. This paper addresses these problems by proposing a retrieval approach that uses a new region-based matching technique equipped with an effective object representation method. In the first stage, the proposed approach selects the most informative instances of each object that appeared in the video by utilizing an adapted clustering algorithm over the extracted features. In the retrieval stage, the new matching technique returns the most relevant sequences of video by mapping a given region with those identified representative instances of objects based on their similarity scores. The proposed approach is evaluated on standard datasets and the results demonstrate a 31% improvement in the retrieval performance compared to other state-of-the-art methods. [ABSTRACT FROM AUTHOR]

This study examined the relationship between the ambient and surface luminances needed to obtain optimal and minimum allowable device (paper and tablet) readability in low ambient illumination environments (illuminance of less than 300 lx). In addition, the optimum and minimum allowable surface luminances were evaluated according to ambient luminance based on the tablet character contrast ratio. Experiments were conducted based on a method in which the subject directly adjusts the surface brightness of the device, and revealed that the contrast ratio does not influence the surface luminance of a tablet. In cases with a set contrast ratio of 70%, paper and tablet were found to produce different results. We propose a model for obtaining optimal and minimum allowable paper and tablet surface luminances in low ambient illuminance environments. The optimal and minimal allowable surface luminances of a tablet are respectively higher and lower than the ambient luminance. In the case of paper, if a surface luminance of at least 27 cd/m 2 can be obtained, the surface luminance can be lower than the ambient luminance. [ABSTRACT FROM AUTHOR]

This article proposes a video encoding method at the residual quad-tree (RQT) level of high-efficiency video coding (HEVC) for JND model-based perceptual coding. This method performs perceptual encoding considering the luminance adaptation characteristics of the human visual system at the RQT level, which determines the partitioning information of the transform unit after determining the motion vectors through motion estimation (a highly complex module in an encoder). In each RQT stage, the proposed algorithm determines the maximum quantization parameter (QP) that reduces the bitrate and simultaneously maintains similar subjective quality, i.e., ensuring no visual quality degradation based on the JND model compared to the initial QP value. To evaluate the performance of the proposed method, a JND model-based RQT-level multi-loop encoding method is applied to the HM16.0 HEVC reference software. Experimental results with a random access configuration of the common test condition show that the bitrate is reduced, on average, by 5.78% and 10% for Class A and Class B videos, respectively; the maximum reduction is 25.3% with the almost same visual quality. [ABSTRACT FROM AUTHOR]

Digital Watermarking is an important method of protecting the intellectual property and copyright of the digital media. In this paper, a new digital video watermarking algorithm Color Watermark Embedding Algorithm (CWEA) is proposed. CWEA has two important parts. First, YCbCr color format is used to insert the variable size watermark. Second, embedding of detail coefficients of LUMINANCE (Y-luminance) of the watermark into the detail coefficients of CHROMINANCE (Cb and Cr- chrominance) of identical frames (I-Frames) of digital video. Data is inserted into the detail coefficients in an adaptive manner based on the energy of high frequency. A number of tests have been executed for many video-frame manipulations and attacks. All these tests are also performed on CWEA and it provides good results. In this paper, non-blind and semi-blind watermarking systems are used where the non-blind watermarking mechanism has been proved to be robust, imperceptible and efficient to protect the copyright of H.264 and MPEG-4 coded video within the video retrieval system. [ABSTRACT FROM AUTHOR]

Infrared video applications such as target detection and recognition, moving target tracking, and so forth can benefit a lot from visual saliency detection, which is essentially a method to automatically localize the “important” content in videos. In this paper, a novel visual saliency detection method for infrared video sequences is proposed. Specifically, for infrared video saliency detection, both the spatial saliency and temporal saliency are considered. For spatial saliency, we adopt a mutual consistency-guided spatial cues combination-based method to capture the regions with obvious luminance contrast and contour features. For temporal saliency, a multi-frame symmetric difference approach is proposed to discriminate salient moving regions of interest from background motions. Then, the spatial saliency and temporal saliency are combined to compute the spatiotemporal saliency using an adaptive fusion strategy. Besides, to highlight the spatiotemporal salient regions uniformly, a multi-scale fusion approach is embedded into the spatiotemporal saliency model. Finally, a Gestalt theory-inspired optimization algorithm is designed to further improve the reliability of the final saliency map. Experimental results demonstrate that our method outperforms many state-of-the-art saliency detection approaches for infrared videos under various backgrounds. [ABSTRACT FROM AUTHOR]

The most recent approach for measuring the image quality is the structural similarity index (SSI). This paper presents a novel algorithm based on the multi-scale structural similarity index for motion detection (MS-SSIM) in videos. The MS-SSIM approach is based on modeling of image luminance, contrast and structure at multiple scales. The MS-SSIM has resulted in much better performance than the single scale SSI approach but at the cost of relatively lower processing speed. The major advantages of the presented algorithm are both: the higher detection accuracy and the quasi real-time processing speed. [ABSTRACT FROM AUTHOR]

With the purpose of copyright protection for digital video, a novel H.264/AVC watermarking algorithm based on JND model is proposed. Firstly, according to the characteristics of human visual system, a new and more accurate JND model is proposed to determine watermark embedding strength by considering the luminance masking, contrast masking and spatial frequency sensitivity function. Secondly, a new embedding strategy for H.264/AVC watermarking is proposed based on an analysis on the drift error of energy distribution. We argue that more robustness can be achieved if watermarks are embedded in middle and high components of 4×4 integer DCT since these components are more stable than dc and low components when drift error occurs. Finally, according to different characteristics of middle and high components, the watermarks are embedded using different algorithms, respectively. Experimental results demonstrate that the proposed watermarking algorithm not only meets the imperceptibility and robustness requirements, but also has a high embedding capacity. [ABSTRACT FROM AUTHOR]

Scene perception requires the orchestration of image- and task-related processes with oculomotor constraints. The present study was designed to investigate how these factors influence how long the eyes remain fixated on a given location. Linear mixed models (LMMs) were used to test whether local image statistics (including luminance, luminance contrast, edge density, visual clutter, and the number of homogeneous segments), calculated for 1° circular regions around fixation locations, modulate fixation durations, and how these effects depend on task-related control. Fixation durations and locations were recorded from 72 participants, each viewing 135 scenes under three different viewing instructions (memorization, preference judgment, and search). Along with the image-related predictors, the LMMs simultaneously considered a number of oculomotor and spatiotemporal covariates, including the amplitudes of the previous and next saccades, and viewing time. As a key finding, the local image features around the current fixation predicted this fixation's duration. For instance, greater luminance was associated with shorter fixation durations. Such immediacy effects were found for all three viewing tasks. Moreover, in the memorization and preference tasks, some evidence for successor effects emerged, such that some image characteristics of the upcoming location influenced how long the eyes stayed at the current location. In contrast, in the search task, scene processing was not distributed across fixation durations within the visual span. The LMM-based framework of analysis, applied to the control of fixation durations in scenes, suggests important constraints for models of scene perception and search, and for visual attention in general. [ABSTRACT FROM AUTHOR]

With the advent of new television standards introducing ultrahigh definition and high dynamic range, backward compatibility with older devices becomes an issue. We propose a method for converting footage produced in BT.2100 colorimetry to a BT.709 compliant representation. The process preserves each pixel's luminance and is fully reversible. Technically, our approach determines the exact polygonal shape of the effective BT.2100 and BT.709 gamuts at a given luminance and maps colors from one to the other by desaturating them. [ABSTRACT FROM AUTHOR]

We propose a novel metric of visual comfort for stereoscopic motion, based on a series of systematic perceptual experiments. We take into account disparity, motion in depth, motion on the screen plane, and the spatial frequency of luminance contrast. We further derive a comfort metric to predict the comfort of short stereoscopic videos. We validate it on both controlled scenes and real videos available on the internet, and show how all the factors we take into account, as well as their interactions, affect viewing comfort. Last, we propose various applications that can benefit from our comfort measurements and metric. [ABSTRACT FROM AUTHOR]

Shot boundary detection is a fundamental step of video indexing. One crucial issue of this step is the discrimination of abrupt shot change from flashlight, because flashlight often induces a false shot boundary. Support vector machine (SVM) is a supervised learning technique for data classification. In this paper, we propose a SVM-based technique to detect flashlights in video. Our approach to flashlight detection is based on the facts that the duration of flashlight is short and the video contents before and after a flashlight should be similar. Therefore, we design a sliding window in temporal domain to monitor the instantaneous video variation and extract color and edge features to compare the visual contents between two video segments. Then, a SVM is employed to classify the luminance variation into flashlight or shot cut. Experimental results indicate that the proposed approach is effective and outperforms some existing techniques. [ABSTRACT FROM PUBLISHER]

Electronic visual displays have shown a rapid technological evolution in the last two decades. With reference to the ergonomic requirements for video display terminal (VDT) workstations (ISO 9241), at an international level, attention is focused on the human–system interaction. With reference to visual ergonomics, the aim of this study is to assess luminance conditions through in-field measurements in order to evaluate: luminance and contrast ratios, luminance and contrast non-uniformities. The assessment was applied to widespread flat screen displays and repeated for fourteen combinations of Contrast–Brightness. The analysis carried out by the Authors shows the importance of realizing a simple and quick procedure to determine the performance levels of displays used in VDT workstations. The proposed assessment could be used as a practical tool for staff assigned to assess the risks arising from VDT use in the workplace within the Occupational Health and Safety Assessment Procedure. [ABSTRACT FROM AUTHOR]

This study investigated errors in color judgment related to stimuli (cyan vs. magenta vs. yellow) printed on various materials (coated paper vs. cotton vs. polyester fiber) and occurring in a range of visual environments (color temperature × luminance: 4000 K × 1500 lx vs. 4000 K × 750 lx vs. 2700 K × 1500 lx vs. 2700 K × 750 lx) under illuminated light-emitting diodes. Participants included 16 female and 14 male Taiwanese college students [age range, 20-26 years (M = 21.92, SD = 2.13)]. Subjects were instructed to perform a series of comparative judgments in which they carefully observed a standard stimulus color under illuminated LEDs and judged which of five simultaneously presented colors under illuminant D65 was the most similar to the standard color. Data analysis revealed that the effect of visual environment on accuracy of color judgments against the standard was significant. Additionally, the accuracy of color judgments against the standard was significantly better for polyester printing material than it was for coated paper. The color of the standard also significantly affected color judgment accuracy: cyan yielded significantly worse accuracy rates than did magenta or yellow. These results have implications for lighting design and interior design. [ABSTRACT FROM AUTHOR]

Watermarking technology is an effective method to clarify the problem of protecting multimedia information. It is the expertise of concealing the information into a host such that the embedded data is invisible. In our strategy luminance band of the selected frames is taken further, it is grouped to alternative pixel shares and flip those images. Two color watermark images are split into distinctive pieces and concatenate its layers, further it is embedded into respective flipped shares under wavelet. Unfold the shares into normal image and stack the designations into single luminance layers. Results achieved the quality of the watermarked frame is high and also the concealed data is requested with acceptably by the human visual system which makes them undetectable. Extraction guarantees that the watermark could be effectively recaptured from a quite short portion of the video. Disguised data are less discernible as well as strong against regular video processing attacks. [ABSTRACT FROM AUTHOR]

The color night-vision technology is advantageous to scene interpretation by displaying original monochrome night-vision imagery with colors, leading the future trend of night-vision development. Until recently, the methods of color night-vision are mostly based on multi-band sensor fusion that do not apply to thermal systems which are only sensitive to one spectral band. To address this, we present a novel technique in this paper aiming to directly give thermal videos day-time color appearance. We observe that the interframe pixel׳s luminance changing over thermal videos approximately follows a Double Lomax distribution. Based on this observation and computational reasons, we propose a star-shape mask for pixel matching. We further show how the mask can be used for efficient thermal video colorization. Additionally, considering the accumulating errors in sequence, we propose a simple region-similarity based abnormal color correction mechanism. Experiments on real applied thermal night-vision videos show that our method can efficiently render single-band thermal sequence with correct colors at 12–33 frame-per-second (fps), providing observers with enhanced facility of surrounding recognition and target recognition. [ABSTRACT FROM AUTHOR]

Abstract Retargeting approaches aim at providing a unified framework for image rendering in which both the intended scene luminance and the actual luminance of the display are taken into account. At the core of any color retargeting method, a color vision model and its inverse are employed. Such a color appearance model should be invertible and cover the entire luminance range of the human visual system. There are not many available models that meet these two conditions. Moreover, most of these models are developed based on psychophysical experiments over color patches, and many have never been used for complex images due to their complexity. In this article, a color retargeting approach based on the mesopic model of Shin et al. ['A color appearance model applicable in mesopic vision,' Opt. Rev. 11, 272-278 (2004)] is developed to work with complex images. The authors propose an inverse model for complex images to compensate for color appearance changes on dimmed displays viewed in a dark environment. Their experimental results using both quantitative and qualitative evaluations show a discriminative improvement in the perceived color quality for mesopic vision. The proposed method can be incorporated into image retargeting techniques and display rendering mechanisms. [ABSTRACT FROM AUTHOR]

An increasing number of studies on efficient implementation of vivid and realistic displays are being conducted as liquid crystal displays (LCDs) become widely used in TV applications. For vivid displays, the specifications such as wide color gamut (WCG) and high dynamic range (HDR) should be implemented in LCDs. However, the low transmittance rate of the WCG and the significant costs for the peak luminance capability of the HDR are major obstacles. Hence, an RGBW LCD, which is capable of increasing the transmission efficiency, may be a good platform to overcome these problems. In this paper, we estimate the perceived brightness effect of the WCG by using the Helmholtz–Kohlrausch (H–K) effect on RGB and RGBW LCDs. The simulation results showed that the RGBW LCD was more suitable for adopting the WCG than the RGB LCD in terms of the brightness balance of achromatic and chromatic colors, and the results were also confirmed by subjective tests. In addition, we propose an effective method to implement the HDR display based on the RGBW LCD. The data stretch, considering a local adaptation characteristic of a human visual system (HVS), greatly enhanced the details of the dark regions, and the local peak dimming using the white channel analysis and the white channel data itself increased the expressiveness of the peak luminance in irradiative or specular regions to 1500 nits. [ABSTRACT FROM AUTHOR]

Since high dynamic range (HDR) displays are not yet widely available, there is still a need to perform a dynamic range reduction of HDR content to reproduce it properly on standard dynamic range (SDR) displays. The most common techniques for performing this reduction are termed tone-mapping operators (TMOs). Although mobile devices are becoming widespread, methods for displaying HDR content on these SDR screens are still very much in their infancy. While several studies have been conducted to evaluate TMOs, few have been done with a goal of testing small screen displays (SSDs), common on mobile devices. This paper presents an evaluation of six state-of-the-art HDR video TMOs. The experiments considered three different levels of ambient luminance under which 180 participants were asked to rank the TMOs for seven tone-mapped HDR video sequences. A comparison was conducted between tone-mapped HDR video footage shown on an SSD and on a large screen SDR display using an HDR display as reference. The results show that there are differences between the performance of the TMOs under different ambient lighting levels and the TMOs that perform well on traditional large screen displays also perform well on SSDs at the same given luminance level. [ABSTRACT FROM AUTHOR]

The current study investigated the role of the inter-screen luminance contrast (ISLC) of trial blank screens between target and mask screens in visually masking scenes. Participants performed a scene gist recognition task in which we varied mask strength, blank screen luminance, and stimulus onset asynchrony (SOA). Results showed that the more luminant white, and less luminant black, blank screens produced greater masking than intermediate luminance gray blank screens adjusted to the mean luminance of the target screens, specifically for black screens at SOAs<36 ms and for white screens at all SOAs. Our findings suggest that researchers interested in controlling for ‘extraneous factors’ should use gray blank screens as they eliminate any contribution of the ISLC component of masking. However, researchers interested in creating and examining differences in processing at early SOAs (<36 ms) should use black blank screens as these were shown to increase variation in the SOA function. [ABSTRACT FROM AUTHOR]

Using projection mapping enables us to bring virtual worlds into shared physical spaces. In this paper, we present a novel, adaptable and real-time projection mapping system, which supports multiple projectors and high quality rendering of dynamic content on surfaces of complex geometrical shape. Our system allows for smooth blending across multiple projectors using a new optimization framework that simulates the diffuse direct light transport of the physical world to continuously adapt the color output of each projector pixel. We present a real-time solution to this optimization problem using off-the-shelf graphics hardware, depth cameras and projectors. Our approach enables us to move projectors, depth camera or objects while maintaining the correct illumination, in realtime, without the need for markers on the object. It also allows for projectors to be removed or dynamically added, and provides compelling results with only commodity hardware. [ABSTRACT FROM AUTHOR]

A new display concept for reproduction of high-luminance colors based on a liquid crystal display has been developed using a brighter backlight unit and color mapping algorithms. The new concept is able to display brighter colors close to a peak luminance of a display white than conventional displays so that realistic scene of brighter colors is better reproduced. It may also be one of the future display solutions needed to extend the color gamut in the direction of brighter colors, which is a principal limitation in conventional displays even in high-dynamic range display systems. With the new concept, an xvYCC- (extended-video YCbCr) compatible display can be easily realized. [ABSTRACT FROM AUTHOR]

There are well-known observations of movie content being displayed at different frame rates. Although the terms are not consistent across the industry, four main degradations are observed of the signal as compared to nonsampled motion (i.e., real-world motion): (1) nonsmooth motion, (2) false multiple edges, (3) flickering, and (4) motion blur. In natural imagery, all four of these effects are generally visible at typical movie frame rates. The spatiotemporal window of visibility has proved successful in describing when motion looks distorted from the realworld smooth motion. However, that model predicts only detection performance and does not address the appearance or magnitude of motion distortions. In addition, well-known image capture and display parameters are also involved with frame rate questions, such as exposure duty cycle (angle), object speed, and object contrast. There are also known interactions with brightness and contrast, which are also generally linked in the end-to-end system. For example, the Ferry-Porter law1 of psychophysics indicates the temporal frequency bandwidth of vision increases with increasing adapting luminance. We aimed to isolate the nonsmooth motion component of judder in a psychophysical study by using fundamental test signals, such as the Gabor signal. Two-interval forced choice methodology was used to generate interval scales of the magnitude of judder, or juddemess. Results are presented for the viewer assessment of the magnitude of judder I juddemess as a function of these key parameters tested in isolation. [ABSTRACT FROM AUTHOR]

This paper discusses the implementation of high dynamic range in the coming generation of studio home entertainment video formats and the technical considerations that led to the adoption of a perceptually-tuned electro-optical transfer function for high dynamic range mastering and distribution. It also covers the value of display-referred systems based on a reference rendering versus historical scene-referred systems based on relative luminance and camera characteristics. [ABSTRACT FROM AUTHOR]

Using a temporal modulation transfer function, we examined the luminance change during low-frequency driving of liquid crystal displays, which is not perceived as flickers by humans. We also developed a novel liquid crystal mixture that doubles the rewrite interval (relative to the conventional mixture), and realizes an eye-friendly display panel. [ABSTRACT FROM AUTHOR]

Sudden changes in illumination often occur in real world scenarios and may cause considerable difficulties in modeling backgrounds for the state-of-the-art background subtraction methods. In this paper, we propose a simple and effective background re-initialization method that detects sudden luminance change effectively. The purpose of the proposed method is not on the presentation of a specific solution for object detection, but is instead the improvement of the background subtraction approach so that it is capable of sudden luminance change adaptation. Two embodiments related to background subtraction, and which are based on the proposed method, are also presented. These embodiments can detect the moving objects accurately as the luminance of the background model is adjusted quickly after the proposed method is employed for generating the background model. Experimental results demonstrate that the proposed method effectively improves the background subtraction methods as measured by qualitative as well as quantitative assessments. [ABSTRACT FROM AUTHOR]

This paper provides a new method to colorize gray-scale images. While the computation of the luminance channel is directly performed by a linear transformation, the colorization process is an ill-posed problem that requires some priors. In the literature two classes of approach exist. The first class includes manual methods that need the user to manually add colors on the image to colorize. The second class includes exemplar-based approaches where a color image, with a similar semantic content, is provided as input to the method. These two types of priors have their own advantages and drawbacks. In this paper, a new variational framework for exemplar-based colorization is proposed. A nonlocal approach is used to find relevant color in the source image in order to suggest colors on the gray-scale image. The spatial coherency of the result as well as the final color selection is provided by a nonconvex variational framework based on a total variation. An efficient primal-dual algorithm is provided, and a proof of its convergence is proposed. In this work, we also extend the proposed exemplar-based approach to combine both exemplar-based and manual methods. It provides a single framework that unifies advantages of both approaches. Finally, experiments and comparisons with state-of-the-art methods illustrate the efficiency of our proposal. [ABSTRACT FROM AUTHOR]

Color video compression has become a necessity in the advent of newer applications of color video and its increasing size for higher definitions. New approaches are used to achieve more compression over the traditional and standard compression techniques. Considerable progress has been made of color transfer-based compression techniques that do not modify standard encoders but add some pre-processing and post-processing steps. We present a novel, simple yet robust, color transfer-based compression technique that can be integrated with the standard encoders like MPEG-2, H.264/AVC, etc. We achieve the compression by discarding the color components from all frames in a video sequence except those of the Intra (I) frames. The colored intra frames are converted to gray-textured images. The method is developed based on embedding the colors of the intra frames to low visibility high frequency textures of its gray luminance image. This is achieved by decomposing the luminance of the intra frame using the non-decimated DWT or discrete wavelet frame transform and replacing the bandpass subbands by the chrominance signals. The lowpass band is same as that of the luminance signal. At the output of the decoder, the colored intra frames are recovered using the wavelet transform. Instead of calculating motion vectors, we identify and reuse the motion vectors present in the decoder. The remaining luminance frames of the video are colored with the help of identified motion vectors and the color information of the preceding frames. The proposed codec considerably improves the compression ratio achievable by the standard codec, at the cost of slight increase in computation time at the decoder end. [ABSTRACT FROM AUTHOR]

The article focuses on the effectiveness of BT. 709 high-efficiency video coding (HEVC) standard for high definition televisions in addressing difficulties in the transformation from one color space to another. Topics discussed include the importance of constant luminance transform for color perception and compares BT.709 to other standard BT.2020, and concept of video colorimetry. Other topics discussed include video quality assessment from colorimetry.

Indirect Illumination is a key element to achieve realistic rendering. Unfortunately, since computing this effect is costly, there are few methods that render it with real-time frame rates. In this paper we present a new method based on virtual point lights and topological information about the scene to render indirect illumination in real-time. [ABSTRACT FROM AUTHOR]

This paper proposes an adaptive watermarking scheme for e-government document images. The adaptive scheme combines the discrete cosine transform (DCT) and the singular value decomposition (SVD) using luminance masking. As a core of masking model in the human visual system (HVS), luminance masking is implemented to improve noise sensitivity. Genetic algorithm (GA), subsequently, is employed for the optimization of the scaling factor of the masking. Involving a number of steps, the scheme proposed through this study begins by calculating the mask of the host image using luminance masking. It is then continued by transforming the mask on each area into all frequencies domain. The watermark image, following this, is embedded by modifying the singular values of DCT-transformed host image with singular values of mask coefficient of host image and the control parameter of DCT-transformed watermark image using Genetic Algorithm (GA). The use of both the singular values and the control parameter respectively, in this case, is not only to improve the sensitivity of the watermark performance but also to avoid the false positive problem. The watermark image, afterwards, is extracted from the distorted images. The experiment results show the improved adaptive performance of the proposed scheme is in resistant to several types of attacks in comparison with the previous schemes; the adaptive performance refers to the adaptive parameter of the luminance masking functioned to improve the performance or robustness of an image from any attacks. [ABSTRACT FROM AUTHOR]

Due to the influence of complex working environment and artificial factors, it is easy to cause crop up over or less tillage problem when straw returning machine is working in paddy field. A new method for path detection suitable for rice, rape and wheat high crop stubble tilling environments was proposed. First the distribution characteristics of rice, rape and wheat high crop stubble images in paddy field based on RGB color model were analyzed, and rice, the color images of rape and wheat high crop stubble were converted into gray ones using custom factor combination R+G-2B; Then, the gray images of rice, rape and wheat high crop stubble were segmented from soil background by means of luminance mean texture descriptor; Next, the binary image through custom shear-binary-image algorithm was cut to remove big noise blobs in high crop stubble's tilled area; Finally, navigation path from navigation points by using the least square method was derived. The experimental results indicated that the navigation path detection algorithm was fast and effective to obtain navigation path in rice, rape and wheat high crop stubble tilling environments with up to 96.7% of segmentation accuracy within 0.6 s of processing time. [ABSTRACT FROM AUTHOR]