Study On The Key Technologies Of JPEG2000 Image Compression And FPGA Implementation

Remote sensing satellite is the most effective way to observe the earth from the space, and it is a important norm to judge the national space technology. With the development of basal technology, the resolution of remote sensing image is more and more high, which results in a lot of data needing to be stored and transferred. But,the storage medium and bandwidth are limited. So, it is essential to compress the remote sensing image. There are three kinds of data redundancy in image, including coding redundancy, pixel redundancy and psychological vision redundancy. If we can reduce or dispel one or more redundancy, we can compress the remote sensing image. There are loss compression and lossless compression, due to the different algorithm. Lossless compression can recover the image absolutely, without any distortion. The lossless compression can increase the compression ratio, but with the big distortion.Wavelet transform has multiresolution, and can provide different image information under the different resolution. The paper proposes the JPEG2000 which base on wavelet transform to compress the remote sensing image. Firstly, wavelet transform dispel the dependency among pixels. Secondly, to quantize the coefficient of wavelet transform. At last, to entropy coding the quantized wavelet transform withembedded block coding with optimized truncation, which can reduce the coding redundancy and output the standardized bit stream.JPEG2000 is characterized by high compression ratio and high signal to noise ratio, and it can realize loss compression and lossless compression at the same time.And it adopts the embedded bit stream coding, so it can transform the image data gradually. The algorithm of JPEG2000 is complicated, and it needs a lot of storage medium. The paper proposes a method to realize the entropy coding, which includes hardware and software. Firstly, it is necessary to structure the CPU using the verilog HDL. Secondly, using the C language codes the entropy coding. At last, to debug the CPU with embedded C language. On the premise of arithmetic speed, it reduces the complexity of the hardware design. The image data of wavelet transform should be limitless. In fact, all the image data is limited. So, it is essential to take measures to deal with the boundary image data. The paper abandons the symmetrical prolongation of boundary image data, and operates the boundary image data independently, which reduces the operation time. During the image compression,there are lots of transitional data need to be stored. The paper uses DDR3 memory to store the data, which can satisfy the needs of high speed transmission.