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Aiming at understanding the role of short-term memory in subjective image quality assessment, we report and compare results from two pair-comparison methods: stimuli shown side-by-side versus stimuli shown one after the other. Our results suggest that there is a significant chance that an observer will make different quality assessments in the two setups.
This paper presents a mathematical analysis of the impact of key-point detection errors on the similarity of local image descriptors that are based on histogram of gradients. First, we derive a closed-form expression for the 𝐿p distance between two descriptors, for general translation, scale and orientation detection errors. Second, we introduce a detailed analysis for the special case where translation...
This paper presents a novel algorithm that aims at minimizing the required decoding energy by exploiting a general energy model for HEVC-decoder solutions. We incorporate the energy model into the HEVC encoder such that it is capable of constructing a bit stream whose decoding process consumes less energy than the decoding process of a conventional bit stream. To achieve this, we propose to extend...
With the aid of tone-mapping operators, high dynamic range images can be mapped for reproduction on standard displays. However, for large restrictions in terms of display dynamic range and peak luminance, limitations of the human visual system have significant impact on the visual appearance. In this paper, we use components from the real-time noise-aware tone-mapping to complement an existing method...
The paper discusses the use of existing metrics, such as HDR-VDP and extensions of MS-SSIM and PSNR, for prediction of quality in high dynamic range (HDR) images and video. The discussion is based on the experience in using those metrics to evaluate and improve image compression for the new JPEG XT standard, and video compression for the LumaHDR open source codec. The paper explains why existing non-HDR...
Depth-Image-Based-Rendering (DIBR) is fundamental in free-viewpoint 3D video, which has been widely used to generate synthesized views from multi-view images. The majority of DIBR algorithms cause disoccluded regions, which are the areas invisible in original views but emerge in synthesized views. The quality of synthesized images is mainly contaminated by distortions in these disoccluded regions...
The just noticeable difference (JND) notion reflects the maximum tolerable distortion. It has been extensively used for the optimization of 2D applications. For stereoscopic 3D (S3D) content, this notion is different since it relies on different mechanisms linked to our binocular vision. Unlike 2D, 3D-JND models appeared recently and the related literature is rather limited. These models can be used...
This paper proposes a new temporal consistency measure for quality assessment of synthesized video. Disocclusion regions appear hole regions of the synthesized video at virtual viewpoints. Filling hole regions could be problematic when the synthesized video is perceived through multi-view displays. In particular, the temporal inconsistency caused by hole filling process in view synthesis could affect...
We propose optimal rate-allocation, using viewer attention information among viewpoints, for depth map cameras within a free-viewpoint television broadcast system. An attention-weighted rate-allocation framework enables bit-rate, or quality, to be distributed across the multiple cameras in accordance with viewer interest, minimizing total observed distortions perceived among all viewers. Prior work...
This paper presents a novel approach for the optimization of calibration parameters in structured light system (SLS). Different with conventional calibration algorithms, the proposed optimization algorithm is implemented in 3D space instead of 2D image space. The object used for parameter optimization can be a simple plane with some markers. A global optimal function is constructed to contain all...
Crowd counting is a very challenging task in crowded scenes due to heavy occlusions, appearance variations and perspective distortions. Current crowd counting methods typically operate on an image patch level with overlaps, then sum over the patches to get the final count. In this paper, we propose an end-to-end convolutional neural network (CNN) architecture that takes a whole image as its input...
This paper addresses the problem of designing a global tone mapping operator for rate-distortion optimized backward compatible compression of HDR images. We consider a two layer coding scheme in which a base SDR layer is coded with HEVC, inverse tone mapped and subtracted from the input HDR signal to yield the enhancement HDR layer. The tone mapping curve design is formulated as the minimization of...
The accuracy of calibration will significantly affect the post processing capability of light field imaging. The geometry of the reconstructed scene is related to the parameters of light field closely, involving the accuracy of decoded rays and ambiguities from ray correspondences. Through exploring the ray correspondence, we derive a transformation matrix to describe the projective distortion on...
It is well known that dispersed and burst packet losses introduce significantly different amount of distortions. Since perceptual models are typically content dependent, it is challenging to characterize how losses interact with concealment. This paper presents loss-pattern-aware distortion (LoPAD), a content-independent metric that explicitly models the impact of different loss patterns. LoPAD operates...
Graph-Based Representation (GBR) has recently been proposed for rectified multiview dataset. The core idea of GBR is to use graphs for describing the color and geometry information of a multiview dataset. The color information is represented by the vertices of the graph while the scene geometry is represented by the edges of the graph. In this paper, we generalize the GBR to multi-view images with...
Binary embedding of high-dimensional data aims to produce low-dimensional binary codes while preserving discriminative power. State-of-the-art methods often suffer from high computation and storage costs. We present a simple and fast embedding scheme by first downsampling N-dimensional data into M-dimensional data and then multiplying the data with an M×M circulant matrix. Our method requires O(N...
A new image specularity removal method is presented in this paper. This method is based on the polarization imaging through global energy minimization. Traditional color-based methods generate severe color distortions, and local-patch-based algorithms produce limited results without integrating the long range information. To handle these limitations, the proposed method uses polarization images to...
We address the problem of optimizing block-coded motion parameters for use inside typical motion-compensating video encoders. We cast the given discrete problem as a nonsmooth nonconvex optimization problem which is defined over some graph, and solve it using the split primal-dual hybrid gradient algorithm. Although computational efficiency is not the main focus of this paper, an efficient, parallelized...
This paper presents a full-reference image quality estimator based on SIFT descriptor matching over reliability-weighted feature maps. Reliability assignment includes a smoothing operation, a transformation to perceptual color domain, a local normalization stage, and a spectral residual computation with global normalization. The proposed method ReSIFT is tested on the LIVE and the LIVE Multiply Distorted...
This paper proposes a reduced reference image quality assessment method using only a low number of features. It involves a shearlet decomposition, directional pooling of the obtained coefficient and extracts the scalewise statistical location parameter as a feature. The proposed method is tested and compared to similar approaches on the LIVE image database. On this database it outperforms the compared...
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