SML映射规则的期望误差一定不会小于GML映射规则的期望误差。而且从算法实现上也可以看出，SML映射规则是一种有偏的映射规则，某些范围的灰度级会被有偏地映射到接近开始计算的灰度级；而GML映射规则是统计无偏的，从根本上避免了上述问题的出现。通过分析可以看出GML映射规则总会比SML映射规则更能体现规定直方图的意图，而且通常产生的误差只有SML映射规则的十几分之一-SML mapping rules of the expectations of the error will not be less than the expectations of the rules of GML mapping error. But also realize from the algorithm can be seen, SML mapping rule is a partial mapping rules, certain areas of the gray-scale will be biased to have mapped to close to the beginning of the calculation of the gray-scale　and GML mapping rules are statistical Unbiased, from the root to avoid the above-mentioned problems. GML can be seen by analyzing the mapping rules will always be better than SML mapping rules better reflect the intent of the provisions of the histogram, and error is usually only a dozen SML mapping rules one