Window of Visibility in the Display and Capture Process

In normal conditions, the Critical Flicker Frequency is usually 60Hz. But in some special conditions, such as low spatial frequency and high contrast between frames, these special conditions have high probability to occur in some TPVMbased applications. So it’s extremely important to verify if a visual signal with a combination of temporal and spatial frequency can be recognize by human eyes. Based on the research in the last paper ’ ’Window of Visibility’ inspired security lighting system’, this paper introduces the measuring method of WoV of humaneyes. In this paper we will measure critical flicker frequency in low spatial frequency and high contrast conditions, and we can witness a different conclusion from the normal conditions

Video steganography based on DCT psychovisual and object motion

Steganography is a technique of concealing the message in multimedia data. Multimedia data, such as videos are often compressed to reduce the storage for limited bandwidth. The video provides additional hidden-space in the object motion of image sequences. This research proposes a video steganography scheme based on object motion and DCT-psychovisual for concealing the message. The proposed hiding technique embeds a secret message along the object motion of the video frames. Motion analysis is used to determine the embedding regions. The proposed scheme selects six DCT coefficients in the middle frequency using DCT-psychovisual effects of hiding messages. A message is embedded by modifying middle DCT coefficients using the proposed algorithm. The middle frequencies have a large hiding capacity and it relatively does not give significant effect to the video reconstruction. The performance of the proposed video steganography is evaluated in terms of video quality and robustness against MPEG compression. The experimental results produce minimum distortion of the video quality. Our scheme produces a robust of hiding messages against MPEG-4 compression with average NC value of 0.94. The proposed video steganography achieves less perceptual distortion to human eyes and it's resistant against reducing video storage

Multi-user interface for co-located real-time work with digital mock-up: a way to foster collaboration?

Nowadays more and more industrial design activities adopt the strategy of Concurrent Engineering (CE), which changes the way to carry out all the activities along the product’s lifecycle from sequential to parallel. Various experts of different activities produce technical data using domain-specific software. To augment the interoperability among the technical data, a Digital Mock-Up (DMU), or a Building Information Model (BIM) in architectural engineering can be used. Through an appropriate Computer–Human Interface (CHI), each expert has his/her own point-of-view (POV) of a specific representation of DMU’s technical data according to an involved domain. When multiple experts work collaboratively in the same place and at the same time, the number of CHIs is also multiplied by the number of experts. Instead of multiple CHIs, therefore, a unique CHI should be developed to support the multiview and multi-interaction collaborative works. Our contributions in this paper are (a) a concept of a CHI system with multi-view and multi-interaction of DMU for multiple users in collaborative design; (b) a state of the art of multi-view and multi-interaction metaphors; (c) an experiment to evaluate a collaborative application using multi-view CHI. The experimental results indicate that, in multi-view CHI working condition, users are more efficient than in the other two working conditions (multiple CHIs and split view CHI). Moreover, in multi-view CHI working condition, the user, who is helping the other, takes less mutual awareness of where the other collaborator works than the other two working conditions.Bourse de thèse de CSC (China Scholarship Council

Design of a digital compression technique for shuttle television

The determination of the performance and hardware complexity of data compression algorithms applicable to color television signals, were studied to assess the feasibility of digital compression techniques for shuttle communications applications. For return link communications, it is shown that a nonadaptive two dimensional DPCM technique compresses the bandwidth of field-sequential color TV to about 13 MBPS and requires less than 60 watts of secondary power. For forward link communications, a facsimile coding technique is recommended which provides high resolution slow scan television on a 144 KBPS channel. The onboard decoder requires about 19 watts of secondary power

Design in context of use: An experiment with a multi-view and multi-representation system for collaborative design

The current trend of product design leads to a change in the collaborative working style. To find the most efficient way to exchange information on the digital mock-up of a product, a synchronous co-located collaborative design environment with recent technologies is in needed. A new groupware of multi-view system allows multiple users to have individual visual information of a domain-specific representation of digital mock-up. In this paper, we propose a case study for the development and testing of a co-located multi-view system in collaborative virtual reality, aiming at enhancing the multidisciplinary early collaborative design. An ergonomic method of Personas is introduced to the evaluation of the tool, considering various user performance. With a multidisciplinary mug design scenario, experiments are presented, validating the benefits of the proposed system.China Scholarship Counci

A human visual system based image coder

Over the years, society has changed considerably due to technological changes, and digital images have become part and parcel of our everyday lives. Irrespective of applications (i.e., digital camera) and services (information sharing, e.g., Youtube, archive / storage), there is the need for high image quality with high compression ratios. Hence, considerable efforts have been invested in the area of image compression. The traditional image compression systems take into account of statistical redundancies inherent in the image data. However, the development and adaptation of vision models, which take into account the properties of the human visual system (HVS), into picture coders have since shown promising results. The objective of the thesis is to propose the implementation of a vision model in two different manners in the JPEG2000 coding system: (a) a Perceptual Colour Distortion Measure (PCDM) for colour images in the encoding stage, and (b) a Perceptual Post Filtering (PPF) algorithm for colour images in the decoding stage. Both implementations are embedded into the JPEG2000 coder. The vision model here exploits the contrast sensitivity, the inter-orientation masking and intra-band masking visual properties of the HVS. Extensive calibration work has been undertaken to fine-tune the 42 model parameters of the PCDM and Just-Noticeable-Difference thresholds of the PPF for colour images. Evaluation with subjective assessments of PCDM based coder has shown perceived quality improvement over the JPEG2000 benchmark with the MSE (mean square error) and CVIS criteria. For the PPF adapted JPEG2000 decoder, performance evaluation has also shown promising results against the JPEG2000 benchmarks. Based on subjective evaluation, when both PCDM and PPF are used in the JPEG2000 coding system, the overall perceived image quality is superior to the stand-alone JPEG2000 with the PCDM