Research On Fast Algorithm Of Laser Speckle Blood Flow Imaging Data Analysis And System Miniaturization

Laser speckle imaging (LSI) is a non-invasive and full-field optical imaging technique, which produces two-dimensional blood flow maps of tissues from the raw laser speckle images captured by a CCD camera or CMOS camera without scanning. It is of great significance in the application of blood flow monitoring in the surgery, skin curing evaluation, retina blood flow monitoring et. al. using LSI technology. Real-time and high speed LSI is quite important in some applications. However, the heavy computation burden of the LSI data analysis algorithm is real a challenge in designing a high speed LSI system. The destination of this paper is to accomplish some fast algorithms for laser speckle imaging data analysis by using optimizing the previous algorithms and bringing in some special computing devices. The main contents of this paper are as blow:(1) We present a more efficient algorithms of LSI data analysis by optimizing the previous algorithms reported based on CPU. This new algorithms owns the superiority over both of performance and the memory consuming. Moreover, we also present a method to further improve the whole performance of LSI data analysis by using multiple core programming.(2) We present a more efficient algorithm of LSI analysis based on GPU (Graphics processing unit) and the computation falls from O(n2) to O(2n) in contrast to the prior GPU based algorithm. When the sliding window size varies from5to17for a raw speckle image, the new method runs roughly1～4times faster than the prior GPU based algorithm. We also make use of multiple GPU for LSI analysis and obtain some further performance enhancement.(3) We present a hardware-friendly algorithm for the real-time processing of laser speckle imaging. The algorithm is developed and optimized specifically for LSI data analysis in the field programmable gate array (FPGA). Based on this algorithm, we designed a dedicated hardware processor for real-time LSI in FPGA. The pipeline processing scheme and parallel computing architecture are introduced into the design of this LSI hardware processor. When the LSI hardware processor is implemented in the FPGA running at the maximum frequency of130MHz, up to85raw images with the resolution of640×480pixels can be processed per second. Meanwhile, we also present a system on chip (SoC) solution for LSI processing by integrating the CCD controller, memory controller, LSI hardware processor, and LCD display controller into a single FPGA chip. This SoC solution also can be used to produce an application specific integrated circuit for LSI processing.(4) Based on the SoC version LSI system, we design a new LSI system that can be used for monitoring the cerebral blood flow of free moving animals by some modifications of the image capturing and image data transferring of the original system. We minimized the components of the raw speckle image capturing and data transferring, so that these components can be placed on the head and the back of the rats. Compared to the prior LSI system used for monitoring the cerebral blood flow of free-moving animals, our system can further increase the degrees of the freedom of experiment animals. Moreover, in order to reduce the size and power consuming of the system, we specially designed a lightweight CPU for the system.