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Laser active imaging system, which is of high resolution, anti-jamming and can be three-dimensional (3-D) imaging, has
been used widely. But its imagery is usually affected by speckle noise which makes the grayscale of pixels change
violently, hides the subtle details and makes the imaging resolution descend greatly. Removing speckle noise is one of
the most difficult problems encountered in this system because of the poor statistical property of speckle. Based on the
analysis of the statistical characteristic of speckle and morphological filtering algorithm, in this paper, an improved
multistage morphological filtering algorithm is studied and implemented on TMS320C6416 DSP. The algorithm makes
the morphological open-close and close-open transformation by using two different linear structure elements respectively,
and then takes a weighted average over the above transformational results. The weighted coefficients are decided by the
statistical characteristic of speckle. This algorithm is implemented on the TMS320C6416 DSPs after simulation on
computer. The procedure of software design is fully presented. The methods are fully illustrated to achieve and optimize
the algorithm in the research of the structural characteristic of TMS320C6416 DSP and feature of the algorithm. In order
to fully benefit from such devices and increase the performance of the whole system, it is necessary to take a series of
steps to optimize the DSP programs. This paper introduces some effective methods, including refining code structure,
eliminating memory dependence, optimizing assembly code via linear assembly and so on, for TMS320C6x C language
optimization and then offers the results of the application in a real-time implementation. The results of processing to the
images blurred by speckle noise shows that the algorithm can not only effectively suppress speckle noise but also
preserve the geometrical features of images. The results of the optimized code running on the DSP platform show that
the optimized outcome realizes better instruction-level parallelism and pipeline operation and the program is proved to
be reliable, effective and high real time.
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