用于数字图像直方图处理的一种二值映射规则

A Binary Mapping Law(BML) for Histogram Processing of Digital Image

直方图表示数字图像中每一灰度级与其出现频数间的统计关系 ,它可给出图像的概貌性描述 ,而基于直方图修改技术的灰度变换是图像增强的实用而有效的处理方法之一。直方图处理包含均衡化和规定化两种技术。均衡化的目的是使图像像素均匀地分布在所有灰度级上 ;规定化的目的是将原图像的直方图转变为规定的直方图 ,以便突出一定灰度范围内的图像。为了进一步提高直方图处理算法的有效性 ,首先分析了现有的几种数字图像直方图均衡化和规定化算法存在的缺点 ,然后提出了一种新的二值映射规则 (BML ) ,该规则基于最优控制原理 ,以直方图误差最小为准则进行灰度映射 ,实验证明 ,该规则算法简单 ,无论是用于直方图均衡化处理 ,还是用于直方图规定化处理 。

Histogram shows the statistic relation between every gray level and the probability of its occurrence, giving the global information of the image. Gray scale transformation based on the technique of histogram modification is one of practical and effective ways of image enhancement. Histogram processing includes equalization and specification. The aim of equalization is to create an image with equally distributed brightness levels over the whole brightness scale; The aim of specification is to transform the histogram of an original image to a specified histogram capable of highlighting certain gray level ranges in the image. In order to improve the efficiency of the algorithm of histogram processing further, the shortcomings of several current algorithms of equalization transformation and specification transformation are first analyzed, then a new binary mapping law (BML) is proposed. That law is based on optimal control theory making gray scale mapping abide by the principle of the minimum error of histogram, and haves a simple algorithm. Whether for histogram equalization or for histogram specification, it is testified more efficient than other mapping laws.