Impact of Noise on Radiological Image Compression

On a PACS network, it is desirable to use a non-destructive image compression technique in order both to minimize the storage and to improve the transmission speed. However, if the effect of noise in images is not taken into account, the expected degree of compression may not be achieved. We have studied some radiological images with different levels of noise using various decomposition methods incorporated with Huffman and Lempel-Ziv coding. When more correlations exist between pixels, these techniques can be made more efficiently. On the other hand, the additional noise disrupts the correlation between adjacent pixels and leads to a less compressed result. Hence, prior to a systematic compression in a PAC system two main issues need to be addressed: a) the true information range which exists in a specific type of radiological image and b) the costs and benefits of compression for the PACS.