螢幕內容編碼SCC的架構是2013年最新制定完成的視訊編碼標準HEVC重點研究方向之一，主要是用於處理多樣化的螢幕畫面內容，包含了由傳統相機捕捉的自然影像，以及大量線條、文字、網頁圖形組成的合成影像。自然影像和合成影像在畫面內容的組成方式有顯著的差異，現行的視訊編碼標準並沒有專門處理該情形的方法，因此提出了SCC的架構來解決目前編碼造成的困難。SCC應用下有兩大編碼工具：一、畫面內區塊複製技術IBC；二、調色盤編碼技術PC。本論文主要是以調色編碼技術的內容做改良，該方法先將編碼單位中的像素值對應到標記出的索引值，並傳送索引值產生的索引顏色表，無法歸類在主要顏色表上的顏色以遺漏像素做處理。目前HM-12.1+RExt-5.1版本中調色盤編碼技術採用高通所提出的方法，因此本論文針對高通的編碼法做改良。
高通版本在處理顏色索引地圖編碼法中採用連續編碼和複製上方的模式，本論文改良原有的兩個模式至四個模式及三個小選項。單一索引模式中專門處理個別出現的索引值；進階複製模式中細分成三個小選項，提供上方、左上和右上起點供複製；連續模式則處理多個索引值相同的情況；遠短模式則在四周搜尋不到相同起點時，至上方遠端搜尋時使用。為驗證本論文提出的改良法比高通編碼法效果更好，將採用HEVC的測試軟體HM來進行實驗，利用PSNR值和Bitrate所構成的RD曲線計算出BD-Rate值比較實驗結果。實驗結果顯示，本論文提出的改良法在SCC應用下對顏色索引地圖大幅增加編碼效率。

Screen Content Coding, one of the standards extended from High Efficiency Video Coding, is mainly used to deal with various content of picture. Content of picture is a combination of natural images and compound images. Both of two images have significant deviation in the content of picture. Therefore, Screen Content Coding is proposed to solve the present difficulty of compound images, which is made by coding. Color Index Map of Palette Coding is mainly improved in this thesis. Color Index Map adopts Qualcomm's method in Version HM-12.1+TExt-5.1 of HM.

Qualcomm version proposed two methods, Copy Above Mode and Run Mode are used for coding current index. However, We increase four new modes and options to improve the method to deal with Color Index Map. The first one single mode, is adopted when current index is different from the indexes around it. The second one is Advance Coding Mode, providing lots of replicable direction such as upper left、upper right and above with many area duplicated simultaneously to improve coding efficiency greatly. The third one is Continuous Mode, used to solve many same indexes. The last one is Above Remote Copy Mode, When current index can't find any same index around it, it will search somewhere further above.

To prove the effect of our new methods, we use HM, test model of HEVC, to do implement and simulation. The experimental result tells that our method can certainly have great improvement on the coding efficiency of various screen content.

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