Dept. of Radiol. Sci., California Univ., Los Angeles, CA.
IEEE Trans Med Imaging. 1996;15(4):547-54. doi: 10.1109/42.511757.
This paper proposes a three-dimensional (3-D) medical image compression method for computed tomography (CT) and magnetic resonance (MR) that uses a separable nonuniform 3-D wavelet transform. The separable wavelet transform employs one filter bank within two-dimensional (2-D) slices and then a second filter bank on the slice direction. CT and MR image sets normally have different resolutions within a slice and between slices. The pixel distances within a slice are normally less than 1 mm and the distance between slices can vary from 1 mm to 10 mm. To find the best filter bank in the slice direction, the authors use the various filter banks in the slice direction and compare the compression results. The results from the 12 selected MR and CT image sets at various slice thickness show that the Haar transform in the slice direction gives the optimum performance for most image sets, except for a CT image set which has 1 mm slice distance. Compared with 2-D wavelet compression, compression ratios of the 3-D method are about 70% higher for CT and 35% higher for MR image sets at a peak signal to noise ratio (PSNR) of 50 dB, In general, the smaller the slice distance, the better the 3-D compression performance.
本文提出了一种用于计算机断层扫描 (CT) 和磁共振 (MR) 的三维 (3-D) 医学图像压缩方法，该方法使用可分离的非均匀 3-D 小波变换。可分离的小波变换在二维 (2-D) 切片内使用一个滤波器组，然后在切片方向上使用第二个滤波器组。CT 和 MR 图像集通常在切片内和切片之间具有不同的分辨率。切片内的像素距离通常小于 1 毫米，切片之间的距离可以从 1 毫米变化到 10 毫米。为了在切片方向上找到最佳的滤波器组，作者使用了切片方向上的各种滤波器组，并比较了压缩结果。来自各种切片厚度的 12 个选定的 MR 和 CT 图像集的结果表明，除了切片距离为 1 毫米的 CT 图像集外，在切片方向上的 Haar 变换对于大多数图像集都能提供最佳性能。与 2-D 小波压缩相比，在峰值信噪比 (PSNR) 为 50 dB 时，3-D 方法的压缩比对于 CT 图像集提高了约 70%，对于 MR 图像集提高了约 35%。一般来说，切片距离越小，3-D 压缩性能越好。
