Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/7178
標題: 多媒體液晶顯示器之動態畫質改善
Quality Improvement for Motion Pictures in Multimedia Liquid-Crystal Displays(LCDs)
作者: 王星發
Wang, Hsing-Fa
關鍵字: dynamic Gamma-Correction;液晶顯示器;TFT LCD;珈瑪;直方圖;動態畫質
出版社: 電機工程學系
摘要: 
摘 要
Gamma-Correction原理指出人眼所能分辨的亮差層次是以對數方式分佈,而非以線性方式分佈。由於Gamma曲線的特性,Gamma-Correction不會影響影像的濃度域(最黑與最白兩階是固定的),而只是影響濃度的分布亮化(當珈瑪值大於1);亮部被擴展而暗部被壓縮。暗化(當珈瑪值小於1)影像;亮部會被壓縮而暗部被擴展。
隨著顯示科技日益進步,其對每一個微小畫素上的影像色彩呈現要求也更加的挑剔。目前有許多新的影像科技與調校技術,Dynamic Gamma Correction(DGC),又稱為Dynamic Gamma Control,使顯示影像色彩的暗度與對比提升,增加黑暗背景層次的豐富感,還原更鮮活亮麗的真實色彩,使其呈現出高亮度、高對比,展現了明亮、清澈的高畫質影像品質。
第三章首先運用影像8灰階分佈統計直方圖(histogram)與即時動態珈瑪電壓修正來達成動態畫質提升。因為所選用的TFT-LCD顯示模組,其珈瑪電壓僅有五組,只能就顯示畫面做大致的調整,其所能得到的畫質雖然比未調整前有很大的改善,但先天上仍有其限制。
第四章則運用32灰階分佈統計直方圖與一種結合影像資料處理的Dynamic Gamma Correction來達成多媒體液晶顯示器之動態畫質提升。針對32灰階來做影像資料的統計,然後搭配外部Gamma Voltage的電壓調整,最後再將原始影像資料以軟體方式做修正處理,形成一條新的珈瑪曲線,使多媒體液晶顯示器呈現出高亮度、高對比,展現了明亮、清澈的高畫質影像品質
在本篇論文有一些問題點存在,所以在第五章結論處提出了一個完整的架構,以使本研究目標“動態影像顯示品質改善”得以改善,並達到盡善盡美的境界。

Abstract
The principle of gamma correction, which is based on brightness levels distinguishable by the human eye, have a logarithmic type distribution and not a non-linear distribution. Gamma correction does not affect density range (The levels of black and white are fixed.) due to the characteristics of the gamma curve. It only lightens density range distribution (when gamma is greater than 1). Bright areas are expanded and dark areas are compressed. For darkened (when gamma is less than 1) images, light areas are compressed and dark areas are expanded.
As display technology advances, more stringent demands are placed on every tiny pixel. There are currently many new image and tuning technologies. Dynamic gamma correction (DGC), also called dynamic gamma control (DGC), improves image darkness and contrast, and then more accurately displays fine images. It achieves higher brightness and contrast and shows clear, crisp high definition image.
As described in chapter 3, an 8-grayscale histogram of dynamic image was construct and immediate gamma voltages were adjusted to improve the image quality of moving pictures on multimedia liquid crystal displays. Since the gamma voltages used on TFT-LCD modules are only 5 externally voltages, it makes rough adjustment to the display. Although, the better image quality is achieved than the before adjustment, but the congenital performance is limited.
Chapter 4 introduces a new dynamic gamma correction method using 32 grayscale histogram and image data processing to improve contrast of moving images on LCDs. First, to statistic the 32 grayscale histograms, then arrange the circuits of combined external gamma voltage adjustment with image data processing by software technology. It will become a new gamma curve, thus more accurately display fine images that have higher contrast and show clear, crisp high definition image quality on multimedia LCDs.
There are still some problems that exist in this work, so a complete framework is proposed in chapter 5 to take the “improvement of moving image quality” research goal to an advance video system.
URI: http://hdl.handle.net/11455/7178
Appears in Collections:電機工程學系所

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