Author: Huang, Zixun
Title: Applications of error diffusion in sub-pixel based downsampling
Advisors: Chan, Yuk Hee (EIE)
Degree: M.Sc.
Year: 2019
Subject: Hong Kong Polytechnic University -- Dissertations
Image processing
Flat panel displays
Liquid crystal displays
Department: Faculty of Engineering
Pages: x, 64 pages : color illustrations
Language: English
Abstract: A pixel on a liquid crystal display (LCD) or organic light-emitting diode (OLED) displays is composed of several controllable subpixels. Subpixel rendering technologies utilize the structural characteristics of the displays to improve the sharpness of the images that need to be displayed. One of the applications of subpixel rendering is image downsampling. Image downsampling is generally used for high quality images when playing them on low resolution display devices. Traditional pixel-based down-sampling methods tend to cause lots of color aliasing artifacts since many lines or edges of the image will be broken. By controlling the subpixels rather than the pixel of the display, subpixel-based image downsampling theoretically can retain more information of the original image to achieve a higher resolution of the down-sampled image. Nevertheless, the increase in resolution is at the expense of color fringing artifacts. It is challenging to achieve higher image resolution while causing less chrominance distortion. In this dissertation, we proposed a new subpixel-based downsampling method called subpixel-based down-sampling with error diffusion (SDwED). Seven performance metrics including LSM, LAM, LCM, CDM, SSIM, S-CIELAB and de are used to evaluate the performance of SDwED and other testing methods, we choose. We also apply SDwED to VPX and VPW panels to verify the adaptability of SDwED. Simulation results shows that SDwED can reduce color aliasing obviously with little color distortion in different testing display layouts. However, the output of SDwED are generally more blurred. To solve this problem, we propose another method called subpixel-based down-sampling with error diffusion and bilateral filtering (SDWEDABF). Our simulation results show that SDWEDABF can improve the edges as compared with SDWED, with slightly more color distortion.
Rights: All rights reserved
Access: restricted access

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