基于小波零樹(shù)的圖像感知熵編碼研究
A STUDY ON THE PERCEPTUAL ENTROPY OF IMAGES USING WAVELET TRANSFORM
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摘要: 本文以小波作為編碼框架,通過(guò)對(duì)人工合成圖像的主觀實(shí)驗(yàn),得出小波變換域中各不同頻帶的視覺(jué)誤差閾值函數(shù),進(jìn)而提出了一個(gè)新的量化編碼方案。該方案基于小波域非均勻零樹(shù)結(jié)構(gòu)量化和高頻低能系數(shù)的視覺(jué)非均勻量化。對(duì)實(shí)際圖像的感知熵和幾乎透明的情形作了研究,與JPEG標(biāo)準(zhǔn)也作了比較。實(shí)驗(yàn)表明該方案較充分、自適應(yīng)地考慮人眼視覺(jué)冗余,具有穩(wěn)健、實(shí)際可行的特點(diǎn)。對(duì)自然圖像,在十倍壓縮比左右可有視覺(jué)無(wú)失真質(zhì)量。
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關(guān)鍵詞:
- 感知編碼; 感知熵; 小波變換; 零樹(shù)
Abstract: In this paper,perceptual error threhhold (PET) functions in different wavelet subbands are obtained through subjective tests on artificial patterns，A new and generic two stage coding scheme is thus proposed,based on the nonuniform zero-trees of wavelet coefficients and the visually nonuniform quantization of small coefficients in higher subbands.Researches have been done for the visual transparent and nearly transparent cases,in comparisons with JPEG standard.Experimental results showed the feasibility and robustness of the scheme,Transparent quality can be obtained around 10 compression ratios for natural images. -
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