本篇論文中，我們改良MPEG-4 Optimize Model中的Sprite演算法以提升演算速度及品質。主要改進項目如下：快速影像變形 (Fast Image Warping)，混成模式全域動態預測 (Hybrid Model Global Motion Estimation)，以及模式選擇器 (Adaptive Model Switching)。

快速影像變形將原先所用的雙線性內插(Bilinear Interpolation)改為最近鄰點內插(Nearest Neighborhood Interpolation)。混成模式全域動態預測則提升影像的品質與精度，所產生的Sprite品質優於或略等於原先使用雙線性內插的影像。而模式選擇器則自動選擇最適當的模式，可以進一步節省運算時間，並省去不必要的資料傳輸量。

實驗使用四組測試影像，其中兩組將畫面順序倒反播放。實驗結果顯示，影像中的攝影機運動越複雜，影像品質的改良越大，而演算速度則保持1.7倍或是約略相等的水平。

A novel sprite generator, base on Yan Lu’s work in MPEG-4 Optimized Model (MPEG-4 OM), is presented in the thesis. Three improvements are included in the generator: fast image warping, hybrid model global motion estimation (GME) and adaptive switching.

To accelerate the speed of image warping, a simpler interpolation kernel is used. The bilinear interpolation kernel is replaced by nearest neighborhood (NN) kernel. Hybrid model GME is used to enhance the image quality and estimation accuracy. With hybrid model GME, the sprite generated with NN kernel has equal or even better quality compared with those generated with Yan Lu’s method. The adaptive switching chooses the proper GME model frame by frame. It saves the computation time and the transmission data rate.

Four test sequences are used to test the new generator. Two of the sequences are reversed frame by frame. The experimental results show that the image quality is improved more if the camera operations are more complex and faster. The computation speed is 1.7 times faster or equal to the OM generator.

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