High-definition Television Images Research Articles

Transmission of 3D holographic information over a radio channel by a method close to SSB

The results of the research on the possibility of transmitting holographic information over the Wi-Fi 40 MHz radio channel are presented. It is shown that the use of two main 3D image modalities for this, — a depth map of the holographic object and the texture of its surface, is sufficient to synthesize a full-fledged hologram at the receiving end of the communication channel, restoring the holographic object with continuous vertical and horizontal parallax. The method of transmitting 3D holographic information is similar to the well–known in radio engineering method of transmitting information on one sideband (Single-sideband modulation, SSB). The essential difference of the proposed method is that the spatial frequencies forming the hologram are the result of simultaneous amplitude and phase modulation of the reference signal. This complicates their theoretical analysis. Experimental confirmation of the possibility of such a transfer was performed using a free FTP client with open source FileZilla. A communication protocol has been applied to transmit information over a wireless Wi-Fi channel. It is shown that the transmitted information stream is sufficient to synthesize a hologram reconstructing 3D images at the receiving end of the communication channel. At the same time, the holographic image of a dynamically changing object with a television frame rate has continuous horizontal and vertical parallax, and the spatial resolution of the restored image was no worse than a high-definition television image of Full HD. The possibility of transmitting all the necessary information over the radio channel to reproduce a holographic 3D video stream at the receiving end of the channel with a resolution not lower than in high-definition television standards with continuous parallax has been experimentally confirmed.

Office-based procedures in laryngology.

SUMMARYObjectiveDevelopment of transnasal fiberoptic laryngoscopy, integration of an operative channel (OC), the advent of high-definition television imaging, with improvements in laser technology, cleared the way for office-based laryngology. Three treatment categories can be identified: bioendoscopy-guided biopsy; laryngeal injection; laser-assisted surgery.Methods26 patients underwent OBPs at the Otolaryngology Clinic of IRCCS Policlinico San Martino, Genoa, Italy. Sixty-eight procedures were performed: 60 for recurrent respiratory papillomatosis (RRP), 5 for unilateral vocal fold paralysis (UVFP) and 3 for glottic leukoplakias. Neoblucaine 5% was administrated through the operative channel, for local anaesthesia. All procedures were carried out with the physician standing behind the patient. Narrow band imaging (NBI – Olympus Medical) or i-scan (Pentax Medical) were used to enhance the accuracy of the biopsy thanks to identification of atypical vascular patterns. Laryngeal injections were made using a 25G flexible needle. Opera Evo (Quanta system IEC/EN 60825-1:2007) is a hybrid fibre laser that is used for “blanching” and vaporisation of RRP lesions and to treat selected leukoplakias that were previously biopsied.ConclusionsNo major complications occurred during the procedures.

An interpolation algorithm using center coordinates of pixels for converting SDTV images to HDTV images

How to guarantee high image quality is the key point when converting standard-definition television (SDTV) images to high-definition television (HDTV) images. The change of pixel shape from rectangular to square makes traditional interpolation methods inappropriate because traditional methods are based on integer coordinates. In this paper, we propose a novel interpolation algorithm using center coordinates of pixels (IAUCCP). This method revises the color value of each pixel on HDTV images by correcting the pixels’ xy coordinates. After that, considering the huge enlarging multiples, sharpening treatment is done to the HDTV images. Experiments show that our method greatly improves the HDTV image quality comparing with traditional interpolation algorithms.

Narrow-Band Versus White-Light High Definition Television Endoscopic Imaging for Screening Colonoscopy: A Prospective Randomized Trial

Narrow-band imaging (NBI) has been implemented in gastrointestinal endoscopy to improve the contrast of endoluminal pathologic structures, one of the aims being to increase colonic adenoma detection. Previous studies from referral centers have yielded variable and conflicting results with regard to improvement in adenoma detection rates by using NBI. The present large randomized trial was designed to finally settle this issue. In a prospective study performed exclusively in a multicenter private practice setting involving 6 examiners with substantial lifetime experience (>10,000 colonoscopies), 1256 patients (men:women, 47%:53%; mean age, 64.4 y) were randomized to HDTV screening colonoscopy with either NBI or white-light imaging on instrument withdrawal. The primary outcome measure was the adenoma detection rate (ie, number of adenomas/total number of patients). There was no difference between the 2 groups in terms of the general adenoma detection rate (0.32 vs 0.34), the total number of adenomas (200 vs 216), or in detection in subgroups of adenomas. This was despite a minimal, but significantly longer, withdrawal time in the NBI group (8.5 vs 7.9 min; P < .05). Only hyperplastic polyps were found more frequently in the NBI group (P = .03). This large randomized trial in a homogeneous private practice screening setting could not show any objective advantage of the NBI technique over white-light high definition television imaging in terms of improved adenoma detection rate. Contrast enhancement therefore likely will not contribute to a reduction in adenoma miss rates among experienced colonoscopists.

Liquid crystal over silicon device characteristics for holographic projection of high-definition television images

We discuss some fundamental characteristics of a phase-modulating device suitable to holographically project a monochrome video frame with 1280 x 720 resolution. The phase-modulating device is expected to be a liquid crystal over silicon chip with silicon area similar to that of commercial devices. Its basic characteristics, such as number of pixels, bits per pixel, and pixel dimensions, are optimized in terms of image quality and optical efficiency. Estimates of the image quality are made from the noise levels and contrast, while efficiency is calculated by considering the beam apodization, device dead space, diffraction losses, and the sinc envelope.

Presence and Image Quality: The Case of High-Definition Television

Previous research has demonstrated that form variables can increase television viewers' sense of presence. The current broadcasting of high-definition television (HDTV) programming makes testing this relation between form and presence possible in a new context, image quality. In this experiment, television viewers watched either HDTV or standard-definition television images and then rated their viewing experience on a pencil-and-paper questionnaire. The results demonstrate that HDTV provided viewers with a greater sense of presence than the current standard, thus providing empirical evidence for the claim that improved image quality will lead to television viewers' experiencing presence. Additionally, the results suggest that with the coming of HDTV, sensations of presence will be both stronger and more common.

Bandwidth compression of the digitized high-definition television images for transmission via satellites

This paper investigates a subband coding scheme to reduce the transmission bandwidth of the digitized high-definition television (HDTV) images. The HDTV signals are decomposed into seven bands. Each band is then independently encoded. The base band is DPCM encoded and the high bands are encoded by using nonunif orm Laplacian quantizers with a dead zone. By selecting the dead zone on the basis of energy in the high bands, an acceptable image quality is achieved at an average rate of 45 Mbits/s (Mbps). This rate is comparable to some very hardware intensive schemes of transform compression or vector quantization proposed in the literature. The subband coding scheme used in this study is considered to be of medium complexity. The 45-Mbps rate is suitable for transmission of HDTV signals via satellites.

Low-complexity subband encoding for HDTV images

The transmission of high-definition television (HDTV) signals on available digital networks and satellites requires the adoption of sophisticated compression techniques to limit the bit rate requirements and to provide high-quality and reliable service to customers. For processing and transmission of image signals, a low-complexity codec without visible degradation is desired. A low-complexity intraframe subband image coding algorithm is developed. The low band is DPCM encoded and the high bands are PCM encoded. An efficient entropy coder is designed which reduces the overall bit rate significantly. It is shown that high-quality HDTV images can be obtained at as low a bit rate as 45 Mb/s or less with a very low-complexity encoder. For dividing the image into subbands, a new class of quadrature mirror filters (QMFs) called generalized quadrature mirror filters (GQMFs) is used for filtering. Performance is also evaluated by using short kernel filters (SKFs), which are easy to implement and require very few computations. >

Perceived image quality of 16:9 and 4:3 aspect ratio video displays

With the development of high-definition television (HDTV) systems came the 16:9 (width to height) viewing image aspect ratio. This is compared to the National Television System Committee (NTSC) standard ratio of 4:3 (width to height). This variation in width-toheight aspect ratio has led to the question of which ratio is preferred by the viewing public. The use of a paired-comparison preferencejudgment experiment is described that was designed to determine whether or not significant differences exist in image preference between the two aspect ratios. Observers were asked to choose a preferred image from a set of two (NTSC versus HDTV) of various image sizes over 84 separate trials. Three separate image types were used in the study: a portrait, a landscape, and a still life. The results indicate that image quality perception is a function of image aspect ratio. The HDTV image was preferred for all three image types.

Hierarchical block truncation coding of digital HDTV images

A source coding technique for compressing HDTV (high-definition television) digital images for B-ISDN (broadband integrated services digital network) visual services is presented. The proposed technique is called hierarchical block truncation coding (HBTC). It is a combination of the block truncation coding (BTC) technique and a quadtree segmentation method. The quadtree segmentation is used to decompose an image into homogeneous regions so that the BTC method can exploit the nonstationarity of the image data. Bit rates around 1.46 b/pixel are achieved with this method. Experimental results for several HDTV images are presented. It is shown that greater image compression can be achieved by using a hierarchical BTC method in conjunction with quadtree segmentation, than by applying BTC to an image with uniform block divisions, since the correlation of uniform areas is exploited. This is especially true for appropriate images such as HDTV with large uniform areas.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>