Papers by Jack zicong mai
… Signal Processing (DSP …, Jan 1, 2011
High dynamic range (HDR) imaging provides superior picture quality to traditional 8 bit, low dyna... more High dynamic range (HDR) imaging provides superior picture quality to traditional 8 bit, low dynamic range (LDR), image representations. Capturing images/videos in HDR format can avoid problems with over and under exposures. Tone-mapping is a process that converts from HDR to LDR, so that HDR content can be shown on existing displays. Tone mapping has been extensively studied in the context of 2D images/video but not for 3D content. This paper addresses the problem of presenting 3D HDR content on stereoscopic LDR displays and presents a subjective psychophysical experiment that evaluates existing tone-mapping operators on 3D HDR images. The results show that 3D content derived using tone-mapping is much preferred to that is captured directly with a pair of LDR cameras. Global tone-mapping methods (which better preserve global contrast) are found to produce images with better 3D effect than local tone-mapping operators (which produce images with high amounts of detail/texture). Also, the brightness of the tone-mapped images is found to be highly collated with perceived 3D quality.
Subjective quality assessment is widely used to understand and to study human perception of multi... more Subjective quality assessment is widely used to understand and to study human perception of multimedia quality and as a basis for developing objective metrics to automatically predict the quality of audiovisual presentations. There are several recognized international protocols and procedures for reliable assessment of quality in multimedia systems and services, with emphasis on speech, audio and video modalities. However, the aspect of certification is not yet well understood in this context. This paper discusses various issues regarding certification of multimedia quality assessment. To be concrete, the discussion is illustrated by the procedure implemented to assess 3D video compression technologies within the MPEG effort for the definition of a 3D video coding standard. Selected results from four laboratories, Acreo, EPFL, NTNU and UBC, which participated in the assessment are presented. This case study is used in an early attempt to define a process for certification of subjective test campaigns, based on a cross-validation of the test results across different laboratories, towards the ultimate goal of Quality of Experience (QoE) certification.
Contrast effect on 3D and 2D video perception
Quality of Multimedia …, Jan 1, 2011
... Zicong Mai1, Mahsa T. Pourazad1,2, and Panos Nasiopoulos1 ... The p values for six scenes are... more ... Zicong Mai1, Mahsa T. Pourazad1,2, and Panos Nasiopoulos1 ... The p values for six scenes are 0.3990 (Reading), 0.7663 (Interview), 0.9068 (Clapping), 0.4104 (SlowMotion), 0.8228 (McMillan) and 0.8499 (Painting) respectively, which are far above the threshold. ...
Image Processing, …, Jan 1, 2011
For backward compatible high dynamic range (HDR) video compression, the HDR sequence is reconstru... more For backward compatible high dynamic range (HDR) video compression, the HDR sequence is reconstructed by inverse tone-mapping a compressed low dynamic range (LDR) version of the original HDR content. In this paper, we show that the appropriate choice of a tone-mapping operator (TMO) can significantly improve the reconstructed HDR quality. We develop a statistical model that approximates the distortion resulting from the combined processes of tone-mapping and compression. Using this model, we formulate a numerical optimization problem to find the tone-curve that minimizes the expected mean square error (MSE) in the reconstructed HDR sequence. We also develop a simplified model that reduces the computational complexity of the optimization problem to a closed-form solution. Performance evaluations show that the proposed methods provide superior performance in terms of HDR MSE and SSIM compared to existing tone-mapping schemes. It is also shown that the LDR image quality resulting from the proposed methods matches that produced by perceptually-based TMOs.
Image Processing (ICIP), …, Jan 1, 2010
We develop a tone-mapping operator (TMO) that considers the perceptual quality of the tone-mapped... more We develop a tone-mapping operator (TMO) that considers the perceptual quality of the tone-mapped image together with the compression efficiency. The proposed TMO is formulated as an optimization problem that incorporates statistical models of i) the quality of the tone-mapped image given a desired TMO, ii) the base layer bit-rate and iii) the enhancement layer bit-rate. The results show that our method achieves high coding gain while maintaining good quality tone-mapped images.
CONTENT 2011, The Third …, Jan 1, 2011
There are several different factors that affect the perceived quality of 3D content. Our objectiv... more There are several different factors that affect the perceived quality of 3D content. Our objective in this paper is to study how the change of contrast between the objects of interest and the background in a scene will affect the overall 3D visual perception. For this study, we captured outdoor and indoor scenes in 3D format. For each scene, the brightness of the background was consistent and the object's brightness was changing using an external light source and/or a reflector disk. Subjective evaluations were performed, with the subjects being asked to rate the 3D perceptual quality of each sequence. The results showed that the Weber contrast between objects of interest and background should be within the range of -0.35 to 0.55 to provide viewers with high quality of 3D experience.
A wavelet-based intra-prediction lossless image compression scheme
Consumer Electronics, 2009. …, Jan 1, 2009
Abstract We propose a wavelet-based intra-prediction image coding scheme that is very efficient f... more Abstract We propose a wavelet-based intra-prediction image coding scheme that is very efficient for lossless compression. This scheme takes advantage of JPEG-2000's wavelet decomposition and H. 264's intra-prediction capability to compress still images. The ...
… , IEEE Transactions on, Jan 1, 2008
The demand for interactive TV services is rapidly increasing. Most of the interactive TV systems ... more The demand for interactive TV services is rapidly increasing. Most of the interactive TV systems are based on the DVB-MHP (Digital Video Broadcast -Multimedia Home Platform) format. Given the unprecedented success of DVD technology and its already established installed base, it is definitely in the interest of manufactures and end-users to be able to play back DVB-MHP iTV content using a Blu-ray player. This study addresses how such programs could be played by the Blu-ray system in real-time. One of the main challenges in realizing this compatibility is the conversion of the "system information" data. These data carry the information about the broadcasting programs and services. This paper first analyzes the differences in system information between the two standards, DVB-MHP and Bluray; mainly the information each standard requires, where this information is stored, and how it is organized. We then propose methods to transcode this information in real-time.
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Papers by Jack zicong mai