WPF：图像处理（四）大津法(2)

            Int32 MaxGrayLevel = Array.FindLastIndex(Histogram, NonZero);   // 最大灰度值 
 
            // 计算最大类间方差 
            Int32 Threshold = MinGrayLevel; 
            Double MaxVariance = 0.0;       // 初始最大方差 
            Double U0 = 0;                  // 初始目标质量矩 
            Int32 C0 = 0;                   // 初始目标点数 
            for (Int32 i = MinGrayLevel; i < MaxGrayLevel; i++) 
            { 
                if (Histogram[i] == 0) continue; 
 
                // 目标的质量矩和点数                 
                U0 += i * Histogram[i]; 
                C0 += Histogram[i]; 
 
                // 计算目标和背景的类间方差 
                Double Diference = U0 * SumC - SumU * C0; 
                Double Variance = Diference * Diference / C0 / (SumC - C0); // 方差 
                if (Variance > MaxVariance) 
                { 
                    MaxVariance = Variance; 
                    Threshold = i; 
                } 
            } 
 
            // 返回类间方差最大阈值