分析了文献[1](张专成，张孝杰，邹涛．用于数字图像直方图处理的一种二值映射规则．中国图象图形学报，2004，9(3)：280-284)中用于直方图规定化的“二值映射规则”，指出该规则与文献[2](Zhang YJ．Improving the accuracy of direct histogram specification．IEE Electronics Letters，1992，28(3)：213-214)中的“组映射规则”是一致的。同时还分析了文献[1]中的直方图均衡化方法，指出该方法采用的并不是上述的映射规则，但要对其性能进行全面评价还需要研究对均衡化效果进行评价的准则。

This paper looks into the so called“Binary Mapping Law”for histogram specification presented in[1] (ZHANG Zhuan-cheng,et al. A binary mapping law(BML) for histogram processing of digital image. Journal of Image and Graphics, 2004,9(3):280～284) and points out that it is identical to the“Group Mapping Law” presented in[2](Zhang Y J. Improving the accuracy of direct histogram specification. IEE Electronics Letters, 1992,28(3):213～214). This paper also looks into the histogram equalization method presented in[1] and indicates that it is different from the histogram equalization method resulted directly from histogram specification and a thorough assessment of the performance of this method needs some more general criteria for evaluationg the performance of histogram equalization techniques.