WPF：图像处理（四）大津法

[csharp] 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; 
        } 
    } 
} 


作者：秦建辉

补充：Web开发 , ASP.Net ,