所谓直方图就是在某一灰度级的象素个数占整幅图像的象素比 h=nj/N,其中nj是灰度级在j的象素数，N是总象素数，扫描整幅图像得出的h的离散序列就是图像的直方图，h求和必然＝1，所以直方图可以看成是象素对于灰度的概率分布函数。-Histogram is the so-called gray level in a given number of pixels representing the entire image pixel than h = nj/N, which nj is the gray level of pixels in the j number, N is the total number of pixels, scanning the whole lot images derived from the discrete sequence h is the image histogram, h summation is bound = 1, so the histogram can be viewed as the probability of pixel gray-scale for the distribution function.