C#图片处理之:最简单的柔化算法

与锐化相反，柔化是使图片看起来更柔滑（其实也是模糊的委婉的说法）。柔化的一个最简单的实现算法就是取图片上的每一点（图片边缘点忽略），计算它周围八个点的平均值作为新像素值。想想也是，之所以看起来模糊，确实是因为周围的点长的有点像，区别不太明显。


// ============================柔化==============================




/**//// <summary>


/// 柔化


/// <param name="b">原始图</param>


/// <returns>输出图</returns>


public static Bitmap KiBlur(Bitmap b)




...{




if (b == null)




...{


return null;


}




int w = b.Width;


int h = b.Height;




try




...{




Bitmap bmpRtn = new Bitmap(w, h, PixelFormat.Format24bppRgb);




BitmapData srcData = b.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);


BitmapData dstData = bmpRtn.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.WriteOnly, PixelFormat.Format24bppRgb);




unsafe




...{


byte* pIn = (byte*)srcData.Scan0.ToPointer();


byte* pOut = (byte*)dstData.Scan0.ToPointer();


int stride = srcData.Stride;


byte* p;




for (int y = 0; y < h; y++)




...{


for (int x = 0; x < w; x++)




...{


//取周围9点的值


if (x == 0 || x == w - 1 || y == 0 || y == h - 1)




...{


//不做


pOut[0] = pIn[0];


pOut[1] = pIn[1];


pOut[2] = pIn[2];


}


else




...{


int r1, r2, r3, r4, r5, r6, r7, r8, r9;


int g1, g2, g3, g4, g5, g6, g7, g8, g9;


int b1, b2, b3, b4, b5, b6, b7, b8, b9;




float vR, vG, vB;




//左上


p = pIn - stride - 3;


r1 = p[2];


g1 = p[1];


b1 = p[0];




//正上


p = pIn - stride;


r2 = p[2];


g2 = p[1];


b2 = p[0];




//右上


p = pIn - stride + 3;


r3 = p[2];


g3 = p[1];


b3 = p[0];




//左侧


p = pIn - 3;


r4 = p[2];


g4 = p[1];


b4 = p[0];




//右侧


p = pIn + 3;


r5 = p[2];


g5 = p[1];


b5 = p[0];




//右下


p = pIn + stride - 3;


r6 = p[2];


g6 = p[1];


b6 = p[0];




//正下


p = pIn + stride;


r7 = p[2];


g7 = p[1];


b7 = p[0];




//右下


p = pIn + stride + 3;


r8 = p[2];


g8 = p[1];


b8 = p[0];




//自己


p = pIn;


r9 = p[2];


g9 = p[1];


b9 = p[0];




vR = (float)(r1 + r2 + r3 + r4 + r5 + r6 + r7 + r8 + r9);


vG = (float)(g1 + g2 + g3 + g4 + g5 + g6 + g7 + g8 + g9);


vB = (float)(b1 + b2 + b3 + b4 + b5 + b6 + b7 + b8 + b9);




vR /= 9;


vG /= 9;


vB /= 9;




pOut[0] = (byte)vB;


pOut[1] = (byte)vG;


pOut[2] = (byte)vR;




}




pIn += 3;


pOut += 3;


}// end of x




pIn += srcData.Stride - w * 3;


pOut += srcData.Stride - w * 3;


} // end of y


}




b.UnlockBits(srcData);


bmpRtn.UnlockBits(dstData);




return bmpRtn;


}


catch




...{


return null;


}




} // end of KiBlur

当然这是最简单的一种，不支持柔化半径选择。实际中通常需要自定义模糊的程度，这个下回再谈。