histogramn.柱状图histogram linear matching灰度线性匹配histogram sequence of LBP局部二值模式直方图序列histogram-based feature音频特征直方图histogram threshold value直方图阈值histograms of color images彩色直方图histogram-equalized image直方图均衡化图像histogram character function直方图函数histogram computation method直方图统计方法histogram density estimation直方图估计histogram double equalization直方图双向均衡