排序方式: 共有34条查询结果,搜索用时 15 毫秒
31.
基于菱形编码和修改量化表的DCT域图像隐写 总被引:1,自引:0,他引:1
为了提高离散余弦变换(DCT)域隐写的嵌入容量,提出一种基于菱形编码和修改量化表的DCT域图像隐写.首先将载体图像进行8×8的DCT变换后,对变换得到的DCT系数采用修改的8×8量化表进行量化,从而提高了嵌入容量和载密图像的视觉质量.同时通过改进的菱形编码将8进制的秘密信息嵌入到载体图像量化DCT系数的中频部分,从而进一步提高了嵌入容量.实验结果表明:该隐写算法不但与JPEG压缩标准兼容,而且有效地提高了嵌入容量. 相似文献
32.
The cycloaddition reactions of NH to different bonds on C70 have been studied by the first-principles calculations.The results indicate that the reactivity of cycloaddition reactions is determined by the directional curvature,KD,and the larger binding energy of Eb on the bond C5-C'5 can be ascribed to the unique bond which can be treated as the shortest bond of(5.5)-SWCNT in the four [6,6] ring fusion bonds.This work also discloses that the energy gap of different spin states is decided by the electronic density,and that of the frontier obitals for the bond C5-C'5 is larger than the value for the C4-C'4 bond.Furthermore,the transition state investigation of the two bond addition reactions provides a reaction barrier of 11.10 kcal/mol for the NH cycloaddition to the C5-C'5 bond;whereas,the addition reaction on C4-C'4 is a spontaneous pathway.Herein,the dynamics effect illustrates the [2+1] cycloaddition reaction on the equatorial C5-C'5 bond to be unfavorable. 相似文献
33.
基于非线性预处理的SAR图像浮点数据压缩 总被引:2,自引:0,他引:2
提出了一种基于非线性预处理和DCT的SAR图像浮点数据压缩方法,通过对预处理前后DCT系数的熵和恢复图像信噪比的分析,确定符合SAR数据特征的预处理方法,再应用区域编码对其进行定值压缩。实验表明该方法可取得非常明显的效果。 相似文献
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