空间TDICCD相机图像压缩的提升小波变换实现技术

空间时间延迟积分电荷耦合器件(TDICCD)相机图像压缩2维(2-D)离散小波变换模块的基于常用硬件实现方法实现效率低,为此提出一种适于电荷耦合器件(CCD)图像的(128,N)快速2-D提升小波实现结构. 在CCD图像行方向上,采用16个提出的1维(1-D)行提升小波变换模块快速实现结构并行分解图像,每个模块采用4个延时寄存器的值作为中间值并用2步预测更新步骤融合的结构来计算行小波系数;在行小波系数的列方向上,提出了一种基于多路复用技术的(32,16)列提升小波变换结构,最终实现了2-D提升小波变换. 结果表明,2-D提升小波变换模块能快速稳定地工作,分解1帧图像仅需60.198μs,与传统方法相比,节省时间达到49.90%,节省逻辑资源10.71%,节省寄存器资源11.80%,节省存储器资源12.98%,有效地解决了CCD图像压缩小波变换硬件实现效率低的问题.

Implementation Technology of 2-D Lifting-Based Discrete Wavelet Transform for Space TDICCD Camera

In order to resolve low efficiency of hardware implementation of 2-dimension (2-D) discrete wavelet transform (DWT) based on the method for space time delay and integration charge coupled devices (TDICCD) compression system, a fast implementation structure (128,N) of 2-D lifting-based DWT is proposed. In the direction of line of CCD image, 16 modules of the fast implementation structure of 1-dimension(1-D) line lifting-based DWT are used to decompose image in parallel. Each module uses the value of four delay registers as the intermediate value to compute line wavelet coefficient, which is computed by a fusion structure of two step of prediction and updating. In the direction of line wavelet coefficient, a (32, 16) column lifting-based DWT structure based on multiplexing technology is proposed, which finally completes 2-D lifting-based DWT. The experiment results show that a module of 2-D lifting-based DWT can work fast and stably. The time needed in decomposing a frame image is only 60.198μs. Compared with traditional approaches, the time consuming is decreased by 49.90%, logical resource is decreased by 10.71%, register is decreased by 11.80%, and memory is decreased by 12.98%. Low efficiency of hardware implementation of wavelet module of CCD image compression in space camera is effectively improved.