The author begins with this facet of the algorithm which can reduce the number of the matching of bloks in the process of the search , and therefore designs an optimized fractal image compression algorithm which aims to decrease the complexity of the fractal encoding and reduce encoding time 摘要從減少搜索匹配塊的數(shù)目入手,提出了一種旨在降低分形編碼的復雜度,縮短編碼時間的分武力像壓縮的改進算法。
Theoretically , fractal dimension has powerful ability to classify image blocks , which results in big speed - up ratio in fractal encoding ; and fractal dimension is a continuous value , which enables us to adjust the quality of decoded images by changing the number of classes 在理論上,由于這種維數(shù)具有很好的分類能力,使得這種方法可取得很大的加速比;由于這種維數(shù)是連續(xù)量,還可通過改變分類數(shù)目來調節(jié)解碼圖像的質量。
Note that in fractal encoding , each range block is to compare with domain blocks after some grey - level affine map . hence we first put forward a kind of image quadrature invariant of affine maps above , which can be thought of a generalization of mario feature 由于在分形編碼時值域塊實際上是與經過灰度仿射變換之后的定義域塊進行比較,因此我們首先提出了一種在灰度仿射變換下保持不變的圖像矩不變量,它可看作是mario特征的推廣。
On the basis of the authors ’ results published in this journal [ 67 ] , this paper further proposed two strategies which improved both quality and speed of fractal encoding : one , a priori adding additive white gaussian noise into the image being encoded to reduce the domain blocks that are unlikely to meet the constraint on contrast scaling factors ; the other , range blocks with small standard deviations are directly approximated by the constant block ( i . e . , all the 在筆者原有結果[計算機仿真, no . 8 , 2004 ]的基礎上,本文提出進一步提高解碼圖像質量和編碼速度的方案:一是預先在待編碼圖像中添加高斯白噪聲以進一步減少不滿足對比度因子約束的domain塊的數(shù)目;二是對小方差range塊直接用其均值塊代替以進一步加快編碼速度。
Theoretically , this quadrature can classify image blocks effectively , which bring out big speed - up ratio in fractal encoding ; and this feature is a continuous value , which enables us to adjust the quality of decoded images by changing the number of classes . our experimental results show that , comparing with exhaustive search , when the class number is 25 , we obtain 20 times speed - up ratio , with only image degeneration of 2 . 08db , at the same compression ratio _ }速比;這種不變量也是連續(xù)量,大量的數(shù)值實驗表明,因此還可通過改變分類數(shù)目來調竹解碼圖像的質量在壓縮比相同的前提下,與全局搜索法相比,塊分為25類時,可取得約20倍的加速比,而解碼質量只相差2