WPF：图像处理（四）大津法

using System;

namespace Splash.Imaging
{
    /// <summary>
    /// 图像处理：大津法二值化阈值计算方法
    /// </summary>
    public static partial class Binarize
    {
        /// <summary>
        /// 大津法计算阈值
        /// </summary>
        /// <param name="grayArray">灰度数组</param>
        /// <returns>二值化阈值</returns> 
        public static Int32 OtsuThreshold(Byte[,] grayArray)
        {   // 建立统计直方图
            Int32[] Histogram = new Int32[256];
            Array.Clear(Histogram, 0, 256);     // 初始化
            foreach (Byte b in grayArray)
            {
                Histogram[b]++;                 // 统计直方图
            }

            // 总的质量矩和图像点数
            Int32 SumC = grayArray.Length;    // 总的图像点数
            Double SumU = 0;                  // 双精度避免方差运算中数据溢出
            for (Int32 i = 1; i < 256; i++)
            {
                SumU += i * Histogram[i];     // 总的质量矩                
            }
            
            // 灰度区间
            Int32 MinGrayLevel = Array.FindIndex(Histogram, NonZero);       // 最小灰度值
            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
            return Threshold;
        }

        /// <summary>
        /// 检测非零值
        /// </summary>
        /// <param name="value">要检测的数值</param>
        /// <returns>
        ///     true：非零
        ///     false：零
        /// </returns>
        private static Boolean NonZero(Int32 value)
        {
            return (value != 0) ? true : false;
        }
    }
}
using System;

namespace Splash.Imaging
{
    /