提出了基于整数小波变换和多级树集合分裂SPIHT(Set Partitioned in Hierarchical Tree)编码的电力系统录波数据压缩方法。首先对故障录波数据进行整数小波变换,再对变换后系数量化,然后进行一维SPIHT编码形成嵌入式码流,便于系统根据...提出了基于整数小波变换和多级树集合分裂SPIHT(Set Partitioned in Hierarchical Tree)编码的电力系统录波数据压缩方法。首先对故障录波数据进行整数小波变换,再对变换后系数量化,然后进行一维SPIHT编码形成嵌入式码流,便于系统根据通讯线路的负荷情况灵活控制传输码率。整数小波变换运算速度快,节约内存,易于DSP实现。SPIHT编码方法形成的码流易于实现可变码率。仿真结果验证了该方法的有效性。展开更多
In this paper, we propose a secure semi-fragile watermarking technique based on integer wavelet transform with a choice of two watermarks to be embedded. A self-recovering algorithm is employed, that hides the image d...In this paper, we propose a secure semi-fragile watermarking technique based on integer wavelet transform with a choice of two watermarks to be embedded. A self-recovering algorithm is employed, that hides the image digest into some wavelet subbands for detecting possible illicit object manipulation undergone in the image. The semi-fragility makes the scheme tolerant against JPEG lossy compression with the quality factor as low as 70%, and locates the tampered area accurately. In addition, the system ensures more security because the embedded watermarks are protected with private keys. The computational complexity is reduced by using parameterized integer wavelet transform. Experimental results show that the proposed scheme guarantees safety of a watermark, recovery of image and localization of tampered area.展开更多
文摘提出了基于整数小波变换和多级树集合分裂SPIHT(Set Partitioned in Hierarchical Tree)编码的电力系统录波数据压缩方法。首先对故障录波数据进行整数小波变换,再对变换后系数量化,然后进行一维SPIHT编码形成嵌入式码流,便于系统根据通讯线路的负荷情况灵活控制传输码率。整数小波变换运算速度快,节约内存,易于DSP实现。SPIHT编码方法形成的码流易于实现可变码率。仿真结果验证了该方法的有效性。
基金This work was supported by the Higher Education Commission of the Government of Pakistan under the Indigenous Ph.D.Scholarship Program(Grant No.17-5-1(Cu-180)HEC/Sch/2004/4343).
文摘In this paper, we propose a secure semi-fragile watermarking technique based on integer wavelet transform with a choice of two watermarks to be embedded. A self-recovering algorithm is employed, that hides the image digest into some wavelet subbands for detecting possible illicit object manipulation undergone in the image. The semi-fragility makes the scheme tolerant against JPEG lossy compression with the quality factor as low as 70%, and locates the tampered area accurately. In addition, the system ensures more security because the embedded watermarks are protected with private keys. The computational complexity is reduced by using parameterized integer wavelet transform. Experimental results show that the proposed scheme guarantees safety of a watermark, recovery of image and localization of tampered area.
