Erickson B J, Manduca A, Persons K R, Earnest F, Hartman T E, Harms G F, Brown L R
Department of Radiology, Mayo Clinic, Rochester, MN 55905, USA.
J Digit Imaging. 1997 Aug;10(3):97-102. doi: 10.1007/BF03168595.
The purpose of this article is to assess lossy image compression of digitized chest radiographs using radiologist assessment of anatomic structures and numerical measurements of image accuracy. Forty posterior-anterior (PA) chest radiographs were digitized and compressed using an irreversible wavelet technique at 10, 20, 40, and 80:1. These were presented in a blinded fashion with an uncompressed image for A-B comparison of 11 anatomic structures as well as overall quality assessments. Mean error, root-mean square (RMS) error, maximum pixel error, and number of pixels within 1% of original value were also computed for compression ratios from ratios from 5:1 to 80:1. We found that at low compression (10:1) there was a slight preference for compressed images. There was no significant difference at 20:1 and 40:1. There was a slight preference on some structures for the original compared with 80:1 compressed images. Numerical measures showed high image faithfulness, both in terms of number of pixels that were within 1% of their original value, and by the average error for all pixels. Our findings suggest that lossy compression at 40:1 or more can be used without perceptible loss in the representation of anatomic structures. On this finding, we will do a receiver-operator characteristic (ROC) analysis of nodule detection in lossy compressed images using 40:1 compression.
本文的目的是通过放射科医生对解剖结构的评估以及图像准确性的数值测量，来评估数字化胸部X光片的有损图像压缩。四十张后前位（PA）胸部X光片被数字化，并使用不可逆小波技术以10:1、20:1、40:1和80:1的比例进行压缩。这些图像以盲法呈现，与一张未压缩图像一起用于对11个解剖结构进行A - B比较以及整体质量评估。还计算了从5:1到80:1压缩比下的平均误差、均方根（RMS）误差、最大像素误差以及在原始值1%范围内的像素数量。我们发现，在低压缩率（10:1）时，对压缩图像有轻微偏好。在20:1和40:1时没有显著差异。与80:1压缩图像相比，在某些结构上对原始图像有轻微偏好。数值测量表明，无论是在原始值1%范围内的像素数量方面，还是在所有像素的平均误差方面，图像忠实度都很高。我们的研究结果表明，40:1或更高的有损压缩在解剖结构表示上不会有明显损失。基于这一发现，我们将对使用40:1压缩的有损压缩图像中的结节检测进行接受者操作特征（ROC）分析。
