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In the quest of perceptually optimized video coding, coding textures is representing a challenging case. While a large body of research was put into the perception of static textures, dynamic textures are still not sufficiently explored. In this paper, we focus on short term consistent patches, known as dynamic textures, with a very limited spatial and temporal extent. We estimated the visual distortion...
Multispectral demosaicking, which is an extension of color demosaicking, is a challenging problem because each band is significantly undersampled and thus precise reconstruction is needed for the restoration of high-frequency components, such as edges, textures etc. In general, existing algorithms borrow high-frequency information either from different bands via inter-color correlation or from within...
Sensitivity to spatial details drops across the visual periphery, and hence video streaming systems that gracefully degrades quality away from the viewpoint of the observer, provides an optimum viewing experience with potentially large bitrate savings. As reaction latency is an important performance parameter of such systems, good prediction of future gaze locations at the transmission end is very...
When hiding messages in digital images, care needs to be exercised how the embedding changes are executed in or near saturated pixels. In this paper, we consider three different rules that are currently being used that adjust the embedding in saturated pixels and assess their impact on empirical steganographic security of four modern embedding algorithms. Surprisingly, the rules can have a major effect,...
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...
Character groundtruth for camera captured documents is crucial for training and evaluating advanced OCR algorithms. Manually generating character level groundtruth is a time consuming and costly process. This paper proposes a robust groundtruth generation method based on document retrieval and image registration for camera captured documents. We use an elastic non-rigid alignment method to fit the...
The accuracy of end-to-end distortion (EED) estimation is crucial to achieving effective error resilient video coding. An established solution, the recursive optimal per-pixel estimate (ROPE), does so by tracking the first and second moments of decoder-reconstructed pixels. An alternative estimation approach, the spectral coefficient-wise optimal recursive estimate (SCORE), tracks instead moments...
In this paper we propose a new quality metric to estimate the impact of packet loss on the perceptual quality of encoded video sequences transmitted over error-prone networks. The proposed metric, henceforth referred to as Cumulative Distortion using Structural Similarity (CDSSIM), quantifies the overall structural distortion resulting from bidirectional error propagation in predictively coded, motion...
A joint source-channel rate-distortion (RD) optimization is proposed for video communication systems. The source coding and channel coding options are optimized by seeking the best trade-off between the estimated end-to-end distortion of a video packet and the sum of the number of source bits and forward error correction bits used to encode that packet. The proposed RD algorithm controls the total...
Subjective experimental results are widely used as the ground truth in objective Image Quality Assessment (IQA). Specifically, Pairwise Comparison method has superiority over Mean Opinion Scores (MOS), but there is a problem when measuring the consistency between subjective pairwise comparisons and objective quality predictions. In this paper, we first analyze the existing problem of current evaluation...
In this paper, we propose a novel reduced-reference quality assessment metric for image super-resolution (RRIQA-SR) based on the low-resolution (LR) image information. First, we use the Markov Random Field (MRF) to model the pixel correspondence between LR and high-resolution (HR) images. Based on the pixel correspondence, we predict the perceptual similarity between image patches of LR and HR images...
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...
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...
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...
Based on a diverse range of priors on natural scene images and noise, numerous denoising algorithms have been proposed in the literature. The image quality resulting from different denoising algorithms may vary significantly across a data set. In this work, we propose a denoising algorithm selection framework that chooses among different denoising algorithms using comparison-based image quality assessment...
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...
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...
In this paper we introduce a shape descriptor known as Self Similar Affine Invariant (SSAI) descriptor for shape retrieval. The SSAI descriptor is based on the property that two sets of points are transformed by an affine transform, then subsets of each set of points are also related by the same affine transformation. Also, the SSAI descriptor is insensitive to local shape distortions. We use multiple...
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...
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...
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