纯二维5/3小波变换及其在CT图像无损压缩中的应用

True 2-D 5/3 wavelet transform and its application for CT image lossless compression

小波变换在数字图像处理领域有着广泛的应用,其对图像的处理常采用行列分离处理方式,这种方式不能完全吻合人眼视觉特性。针对这一情况,构造了一种与人眼视觉特性更加吻合的纯二维小波变换处理方式。首先,由一维5/3小波滤波器组通过Mc Clellan变换构造纯二维5/3小波滤波器组,并用提升格式实现;然后,用该提升格式与纯二维Lazy小波滤波器组相嵌套的形式实现图像的纯二维5/3小波变换。为了便于工程应用,给出了其变换规程。将纯二维5/3小波变换用于CT图像的无损压缩,实验证明:对于512 dpi×512 dpi尺寸的CT图像,纯二维5/3小波变换无损压缩效果高于二维可分离5/3小波变换,每幅图像可平均节省1 989.9 byte。

Wavelet transform is widely used in the field of digital image processing, and it usually processes imageby separating the row and column, which can’t meet the human visual system （HVS） completely. To address thissituation, a kind of true 2-D 5/3 wavelet transform was constructed, which was more consistent with HYS. Firstly,1-D 5/3 wavelet filter bank constructed the true 2-D Lazy wavelet filter bank by McClellan transform, and it wasimplemented by lifting scheme. Then, this lifting scheme was nested with the true 2-D Lazy wavelet filter bank toimplement true 5/3 wavelet transform of image. To facilitate engineering applications, the transformation procedurewas given. The experiments of true 5/3 wavelet transform used in CT image lossless compression, the experimentshows that, for 512×512 size CT image true 5/3 wavelet transform has better compression effect when compared withtwo dimensional separable 5/3 wavelet transform and can save 1 989.9 byte per piece on average.