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題名 | A New ADPCM Image Coder Using Frequency Weighted Directional Filter=使用頻率權重之方向性濾波器設計之ADPCM影像編碼器 |
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作者姓名(中文) | 連振昌; 黃仲陵; | 書刊名 | 電腦學刊 |
卷期 | 10:2 1998.06[民87.06] |
頁次 | 頁12-30 |
分類號 | 312.1 |
關鍵詞 | 方向性濾波器; 影像編碼器; ADPCM; |
語文 | 英文(English) |
中文摘要 | 這篇論文提出一新的ADPCM影像壓縮編碼的方法稱為方向性ADPCM。此方向性ADPCM 影像壓縮編碼方法能夠比傳統ADPCM移除影像訊號中更多的冗資訊。傳統ADPCM藉由二維相 關函數(correlation function)與Yule-Walker公式計算出二維編碼預測係數,而在實際的 應用中,二維相關函數的統計量經常由樣本平均值(sample average)所取代。但是,樣本平 均值僅是二維相關函數的趨近值,樣本點數目愈多,二維相關函數愈能被樣本平均值所趨近, 然而,在影像的封包(packet)傳送過程中,為防止傳送錯誤的累積,影像的分割方塊(block) 大小不能太大,而小方塊的影像分割使得樣本平均值無法準確的逼近二維相關函教。因此, 在這篇論文中,我們提出方向性ADPCM影像壓縮編碼系統,祈能獲得較佳的二維預測編碼效 果。我們所設計之方向性ADPCM影像壓縮編碼系統使用扇形濾波器組來估算每個影像方塊對 每個扇形濾波器的響應,用以計算出二維編碼預測係教,所有的扇形濾波器皆使用 SVD(singular value decomposition),Hilbert Transformation,及頻率權重(frequency weighted)的觀念設計之。最後,在實驗中,我們會舉出此方向性ADPCM影像壓縮編碼方法 能夠比傳統ADPCM由影像訊號中移除更多的冗資訊。 |
英文摘要 | This paper proposes a new ADPCM method for image coding called directional ADPCM which can remove more redundancy from the image signals than the conventional ADPCM. The conventional ADPCM calculates the two-dimensional prediction coefficients by using the correlation functions followed by solving the Yule-Walker equation. Actually, the quantities of correlation functions are replaced by the sample averages. Thus, large amount of sampled data are used for the sample average function which is an approximation of the correlation function. However, the block size is limited by the error accumulation effect during packet transmission. Using small block may induce the unregulated prediction coefficients. Therefore, we need to develop the directional ADPCM system to overcome such a problem and to have better prediction result. Our directional ADPCM utilizes the fan-shape filters to obtain the energy distribution in four directions and then determines the four directional prediction coefficients. All the fan-shape filters are designed by using the singular value decomposition (SVD) method, the two-dimensional Hilbert transform technique, and the frequency weighting concept. In the experiments, we illustrate that the M.S.E for the directional ADPCM is less than that of the conventional ADPCM. |
本系統之摘要資訊系依該期刊論文摘要之資訊為主。