void Calc(unsigned short *Hist, int Intensity, unsigned char *&Pixel, int Threshold)
{int K, Low, High, Sum = 0, Weight = 0;Low = Intensity - Threshold; High = Intensity + Threshold;if (Low < 0) Low = 0;if (High > 255) High = 255;
    for (K = Low; K <= High; K++)    {Sum += Hist[K] * K;Weight += Hist[K];}if (Weight != 0) *Pixel = Sum / Weight;
}

/// <summary>
/// 实现图像选择性图像模糊效果，O(1)复杂度,最新整理时间 2015.8.1。
/// </summary>
/// <param name="Src">需要处理的源图像的数据结构。</param>
/// <param name="Dest">保存处理后的图像的数据结构。</param>
/// <param name="Radius">指定模糊取样区域的大小，有效范围[1,127]。</param>
/// <param name="Threshold">选项控制相邻像素色调值与中心像素值相差多大时才能成为模糊的一部分,色调值差小于阈值的像素被排除在模糊之外，有效范围[1,255]。</param>
IS_RET __stdcall SelectiveBlur(TMatrix *Src, TMatrix *Dest, int Radius, int Threshold, EdgeMode Edge)
{if (Src == NULL || Dest == NULL) return IS_RET_ERR_NULLREFERENCE;if (Src->Data == NULL || Dest->Data == NULL) return IS_RET_ERR_NULLREFERENCE;if (Src->Width != Dest->Width || Src->Height != Dest->Height || Src->Channel != Dest->Channel || Src->Depth != Dest->Depth || Src->WidthStep != Dest->WidthStep) return IS_RET_ERR_PARAMISMATCH;if (Src->Depth != IS_DEPTH_8U || Dest->Depth != IS_DEPTH_8U) return IS_RET_ERR_NOTSUPPORTED;if (Radius < 0 || Radius >= 127 || Threshold < 2 || Threshold > 255) return IS_RET_ERR_ARGUMENTOUTOFRANGE;IS_RET Ret = IS_RET_OK;if (Src->Data == Dest->Data){TMatrix *Clone = NULL;Ret = IS_CloneMatrix(Src, &Clone);if (Ret != IS_RET_OK) return Ret;Ret = SelectiveBlur(Clone, Dest, Radius, Threshold, Edge);IS_FreeMatrix(&Clone);return Ret;}if (Src->Channel == 1){TMatrix *Row = NULL, *Col = NULL;unsigned char *LinePS, *LinePD;int X, Y, K,  Width = Src->Width, Height = Src->Height;int *RowOffset, *ColOffSet;unsigned short *ColHist    = (unsigned short *)IS_AllocMemory(256 * (Width + 2 * Radius) * sizeof(unsigned short), true);    if (ColHist == NULL) {Ret = IS_RET_ERR_OUTOFMEMORY; goto Done8;}unsigned short *Hist    = (unsigned short *)IS_AllocMemory(256 * sizeof(unsigned short), true);    if (Hist == NULL) {Ret = IS_RET_ERR_OUTOFMEMORY; goto Done8;}Ret = GetValidCoordinate(Width, Height, Radius, Radius, Radius, Radius, Edge, &Row, &Col);        //    获取坐标偏移量if (Ret != IS_RET_OK) goto Done8;ColHist += Radius * 256;        RowOffset = ((int *)Row->Data) + Radius;        ColOffSet = ((int *)Col->Data) + Radius;                //    进行偏移以便操作for (Y = 0; Y < Height; Y++){if (Y == 0)                                            //    第一行的列直方图,要重头计算
            {for (K = -Radius; K <= Radius; K++)                    {LinePS = Src->Data + ColOffSet[K] * Src->WidthStep;for (X = -Radius; X < Width + Radius; X++){ColHist[X * 256 + LinePS[RowOffset[X]]]++;}}}else                                                //    其他行的列直方图，更新就可以了
            {LinePS = Src->Data + ColOffSet[Y - Radius - 1] * Src->WidthStep;        for (X = -Radius; X < Width + Radius; X++)        // 删除移出范围内的那一行的直方图数据
                {ColHist[X * 256 + LinePS[RowOffset[X]]]--;}LinePS = Src->Data + ColOffSet[Y + Radius] * Src->WidthStep;for (X = -Radius; X < Width + Radius; X++)        // 增加进入范围内的那一行的直方图数据
                {ColHist[X * 256 + LinePS[RowOffset[X]]]++;}}memset(Hist, 0, 256 * sizeof(unsigned short));        //    每一行直方图数据清零先
LinePS = Src->Data + Y * Src->WidthStep;LinePD = Dest->Data + Y * Dest->WidthStep;for (X = 0; X < Width; X++){if (X == 0){for (K = -Radius; K <= Radius; K++)            //    行第一个像素，需要重新计算    HistgramAddShort(ColHist + K * 256, Hist);}else{HistgramSubAddShort(ColHist + RowOffset[X - Radius - 1] * 256, ColHist + RowOffset[X + Radius] * 256, Hist);  //    行内其他像素，依次删除和增加就可以了
                }Calc(Hist, LinePS[0], LinePD, Threshold);    LinePS++;LinePD++;}}ColHist -= Radius * 256;        //    恢复偏移操作
    Done8:IS_FreeMatrix(&Row);IS_FreeMatrix(&Col);IS_FreeMemory(ColHist);IS_FreeMemory(Hist);return Ret;}else{TMatrix *Blue = NULL, *Green = NULL, *Red = NULL, *Alpha = NULL;            //    由于C变量如果不初始化，其值是随机值，可能会导致释放时的错误。IS_RET Ret = SplitRGBA(Src, &Blue, &Green, &Red, &Alpha);if (Ret != IS_RET_OK) goto Done24;Ret = SelectiveBlur(Blue, Blue, Radius, Threshold, Edge);if (Ret != IS_RET_OK) goto Done24;Ret = SelectiveBlur(Green, Green, Radius, Threshold, Edge);if (Ret != IS_RET_OK) goto Done24;Ret = SelectiveBlur(Red, Red, Radius, Threshold, Edge);if (Ret != IS_RET_OK) goto Done24;                                            //    32位的Alpha不做任何处理，实际上32位的相关算法基本上是不能分通道处理的
        CopyAlphaChannel(Src, Dest);Ret = CombineRGBA(Dest, Blue, Green, Red, Alpha);Done24:IS_FreeMatrix(&Blue);IS_FreeMatrix(&Green);IS_FreeMatrix(&Red);IS_FreeMatrix(&Alpha);return Ret;}
}