The optimized color space is searched by using the wavelet scattering network in the KTH_TIPS_COL color image database for image texture classification. The effect of choosing the color space on the classification accuracy is investigated by converting red green blue （RGB） color space to various other color spaces. The results show that the classification performance generally changes to a large degree when performing color texture classification in various color spaces, and the opponent RGB-based wavelet scattering network outperforms other color spaces-based wavelet scattering networks. Considering that color spaces can be changed into each other, therefore, when dealing with the problem of color texture classification, converting other color spaces to the opponent RGB color space is recommended before performing the wavelet scattering network.
A new method for reconstructing the compressed sensing color image by solving an optimization problem based on total variation in the quaternion field is proposed, which can effectively improve the reconstructing ability of the color image. First, the color image is converted from RGB （red, green, blue） space to CMYK （cyan, magenta, yellow, black） space, which is assigned to a quaternion matrix. Meanwhile, the quaternion matrix is converted into the information of the phase and amplitude by the Euler form of the quatemion. Secondly, the phase and amplitude of the quatemion matrix are used as the smoothness constraints for the compressed sensing （CS） problem to make the reconstructing results more accurate. Finally, an iterative method based on gradient is used to solve the CS problem. Experimental results show that by considering the information of the phase and amplitude, the proposed method can achieve better performance than the existing method that treats the three components of the color image as independent parts.
为了提高TCP/IP协议栈的实时性,并保证其可靠性和可扩展性,满足物联网工程低功耗的需求,采用LPC2124ARM微控制器和ENC28J60网络芯片,实现了嵌入式的TCP/IP精简协议栈.该协议栈以实时操作系统μC/OS-Ⅱ为内核,除了基本TCP/IP协议簇外,还包含了DHCP、ICMP、Socket接口以及DNS协议以增强灵活性和可靠性.使用纯C和汇编语言编写,利用keil进行编译,proteus模拟仿真.完成了系统的移植、硬件驱动和协议栈的实现.使用wireshark等工具进行了一系列的功能、性能测试和实验.实验和测试结果表明,精简的协议栈在实现基本功能的基础上带来了更短的代码量(7.6 K RAM,48K ROM),其UDP传输速率达到了16.5K/s.而且协议栈支持扩展,用户可以根据需求自行设计.
An algorithm for recovering the quaternion signals in both noiseless and noise contaminated scenarios by solving an L1-norm minimization problem is presented. The L1-norm minimization problem over the quaternion number field is solved by converting it to an equivalent second-order cone programming problem over the real number field, which can be readily solved by convex optimization solvers like SeDuMi. Numerical experiments are provided to illustrate the effectiveness of the proposed algorithm. In a noiseless scenario, the experimental results show that under some practically acceptable conditions, exact signal recovery can be achieved. With additive noise contamination in measurements, the experimental results show that the proposed algorithm is robust to noise. The proposed algorithm can be applied in compressed-sensing-based signal recovery in the quaternion domain.
