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面向CALIC的图像加密算法研究
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作者 张淼 佟晓筠 张华 《智能计算机与应用》 2019年第4期315-319,共5页
将图像的加密和压缩结合在一起同步完成可以带来设计上的灵活和计算上的简化,同时也可以更好地保证安全性,为图像信息的安全高效存储和传输做出保障.基于CALIC良好的压缩效率,本文研究并设计了面向CALIC的图像加密算法.根据CALIC编码原... 将图像的加密和压缩结合在一起同步完成可以带来设计上的灵活和计算上的简化,同时也可以更好地保证安全性,为图像信息的安全高效存储和传输做出保障.基于CALIC良好的压缩效率,本文研究并设计了面向CALIC的图像加密算法.根据CALIC编码原理,算法实现在CALIC编码过程中的加密,主要包括GAP预测值的加密、最终残差的加密、明文像素的加密、熵编码码流的加密.实验结果表明面向CALIC的图像加密算法在压缩性能上取得较好效果的同时增加了安全性. 展开更多
关键词 压缩加密联合 混沌 CALIC
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L_∞准则约束下的高质量灰度指纹图像压缩算法 被引量:3
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作者 张宁 章毓晋 +1 位作者 刘青棣 林行刚 《清华大学学报(自然科学版)》 EI CAS CSCD 北大核心 2000年第9期28-32,共5页
为克服基于传统 L2 准则的有损图像压缩算法难以准确控制每一像素值的误差范围 ,因而可能丢失指纹图像特殊细节的缺点 ,提出了一个在 L∞ 准则严格约束下针对灰度指纹图像的高质量图像压缩算法。该算法以当前性能最优的无损图像压缩算法... 为克服基于传统 L2 准则的有损图像压缩算法难以准确控制每一像素值的误差范围 ,因而可能丢失指纹图像特殊细节的缺点 ,提出了一个在 L∞ 准则严格约束下针对灰度指纹图像的高质量图像压缩算法。该算法以当前性能最优的无损图像压缩算法 CAL IC为基础 ,结合了根据指纹局部纹线走向所设计的分类线性预测器 ,并提出了准无损模式下根据量化器对熵编码器自适应调节的方案。对一组真实灰度指纹图像的实验结果表明 ,与 CAL IC算法相比 ,新算法在同样的最大误差下 ,平均比特率降低了 8% ,同时峰值信噪比(PSNR)提高了 1.2 d B。新算法在最大误差不超过± 3个灰度级的情况下 ,实现了 5∶ 1左右的压缩比 ,且比当前 L2 准则下性能最优的压缩算法之一 SPIHT明显具有更高的均方信噪比。 展开更多
关键词 图像压缩 准无损压缩 指纹图像 L∞准则 CALIC
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Preservation of the kidney with delayed diagnosis of traumatic pelvi-ureteric junction disruption secondary to blunt abdominal trauma in children 被引量:2
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作者 LI Ming-lei SUN Ning ZHANG Wei-ping HUANG Cheng-ru BAI Ji-wu LIANG Ruo-xin TIAN Jun XIE Xiang-hui SONG Hong-cheng LI Ning 《Chinese Medical Journal》 SCIE CAS CSCD 2011年第15期2290-2296,共7页
Background The delayed diagnosis of pelvi-ureteric junction (PUJ) disruption in children following blunt abdominal trauma can result in loss of function of the involved kidney. We examined the potential for kidney p... Background The delayed diagnosis of pelvi-ureteric junction (PUJ) disruption in children following blunt abdominal trauma can result in loss of function of the involved kidney. We examined the potential for kidney preservation and the limits of diagnostic delays. Methods A retrospective review of 17 cases of PUJ disruption at Beijing Children's Hospital from 1993 to 2009 was done with respect to diagnosis, treatment and follow-up. Results The interval from trauma to diagnosis of PUJ disruption was (52+52) days. If one case with nephrectomy was excluded, the interval from trauma to diagnosis was (40+_20) days. The average time between injury and first treatment was (49+_25) days. Pelvi-ureteric reanastomosis and caliceal ureterostomy were performed separately in 11 and 4 patients, respectively. Ileal replacement for ureter injuries was finally performed in one patient. Hydronephrosis of the injured kidney was reduced and the function improved in 15 out of 17 patients (88%). Only one patient received nephrectomy and the nephrectomy rate was 5.9%. Conclusion Differential renal function at the PUJ disruption side can be saved and the rate of nephrectomy reduced by appropriate surqen/if the time to diaqnosis and first treatment is limited to within two months. 展开更多
关键词 wounds and injuries HYDRONEPHROSIS URETER kidney pelvis kidney calices CHILDREN
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