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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Crosstalk in Stereoscopic LCD 3-D Systems

Feng, Hsin-Chang January 2015 (has links)
Stereoscopic 3-D has received considerable attention over the last few decades. Since a stereoscopic 3-D pair includes two 2-D images together, the amount of data for an uncompressed stereo image is double compared to that for an uncompressed 2-D image. Thus efficient compression techniques are of paramount importance. However, crosstalk effect is an inherent perceivable problem in current 3-D display technologies. It can lead not only to degradation in the perceived quality of 3-D images, but also to discomfort in some individuals. Correspondingly, when crosstalk occurs, the compression artifacts in a compressed stereo pair can be perceived, despite the fact that such artifacts are imperceptible in individual left and right images. This dissertation proposes a methodology for visually lossless compression of monochrome stereoscopic 3-D images in which crosstalk effect is carefully considered. In the proposed methodology for visually lossless compression of monochrome stereoscopic 3-D images, visibility thresholds are measured for quantization distortion in JPEG2000 to conceal perceivable compression artifacts. These thresholds are found to be functions of not only spatial frequency, but also of wavelet coefficient variance, as well as the gray level in both the left and right images. In order to avoid a daunting number of measurements of visibility thresholds during subjective experiments, a model for visibility thresholds is developed. The left image and right image of a stereo pair are then compressed jointly using the visibility thresholds obtained from the proposed model to ensure that quantization errors in each image are imperceptible to both eyes. This methodology is then demonstrated via a 3-D stereoscopic liquid crystal display (LCD) system with an associated viewing condition. The resulting images are visually lossless when displayed individually as 2-D images, and also when displayed in stereoscopic 3-D mode. In order to have better perceptual quality of stereoscopic 3-D images, hardware based techniques have been used to reduce crosstalk in 3-D stereoscopic display systems. However, crosstalk is still readily apparent in some 3-D viewing systems. To reduce crosstalk remains after hardware crosstalk compensation, a methodology for crosstalk compensation accomplished via image processing is provided in this dissertation. This methodology focuses on crosstalk compensation of 3-D stereoscopic LCD systems in which active shutter glasses are employed. Subjective experiments indicate that crosstalk is a function of not only the pixel intensity in both the left and right channels, but also of spatial location. Accordingly, look-up tables (LUTs) are developed for spatially-adaptive crosstalk compensation. For a given combination of gray levels in the left and right channels at a specific spatial location, the original pixel values are replaced by values contained in the LUTs. The crosstalk in the resulting stereo pair is significantly reduced, resulting in a significant increase in perceptual image quality.
2

Přenosová technologie G.mgfast / G.mgfast transmission technology

Rada, Dominik January 2021 (has links)
The master thesis deals with G.fast and G.mgfast transmission technologies, including their parameters. The work deals with the principle of vector DMT modulation and the possibility of time duplex TDD and full-duplex FDX in two-way communication used in these technologies. The following is a description of the line using the KHM model, which is suitable for simulations in the transmission band using G.fast and G.mgfast technologies. Subsequently, the disturbing effects of crosstalk at the near end of NEXT and the far end of FEXT and their elimination with these technologies are discussing. Part of the work explains supporting calculations to determine the SNR and bit allocation to calculate the baud rate. The work describes the methods of compensation of crosstalk FEXT and NEXT, which affect the resulting baud rate. The work also includes an application for simulation of transmission speed as a function of distance for G.fast and G.mgfast technologies, allowing changing input parameters and adjusting the transmission bandwidth based on G.9700 and G.9701 standards. Also, in work, an application is created to display the compensation of the influence of the transmitted signal crosstalk FEXT and NEXT, which allow the import of measured crosstalk between individual participants. The issue of influencing crosstalk for accurate measurements in the laboratory is also discussing. An application in the MATLAB environment is creating to display the measured characteristics.

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