滤镜之毛玻璃FrostedGlass

首先看这两张效果图：

毛玻璃看上去是一些离散的点分布，而这些点是周围像素点的反映。所以需要用到随机值。

算法原理：

1.     统计像素周围区域内的R、G、B的直方图，直方图横坐标是每个像素的灰度值，统计以及每个灰度值的强度

2.     从直方图中随机选取一个灰度强度下的R、G、B的均值就是目标像素结果

该算法存在一个参数：

1.     半径：越大则毛刺更严重，随机范围越大

算法代码：没有经过任何优化

void FrostedGlassRGB(unsigned char* pInput,unsigned char* pOutput,int width,int height,int nStride,int radius)
{int intensity;int red[256],green[256],blue[256],intensities[256];unsigned char* src = pInput;unsigned char* dst = pOutput;unsigned char* p;int i,j,x,y,t;int offset = nStride-width*3;if(pInput == NULL || pOutput == NULL)return;if(width <= 0 || height <= 0)return;if(radius<1)radius = 1;srand ((unsigned int)time(0));// for each linefor ( y = 0; y < height; y++ ){// for each pixelfor ( x = 0; x < width; x++, src += 3, dst += 3 ){memset(red,0,sizeof(int)*256);memset(green,0,sizeof(int)*256);memset(blue,0,sizeof(int)*256);memset(intensities,0,sizeof(int)*256);// for each kernel rowfor ( i = -radius; i <= radius; i++ ){t = y + i;// skip rowif ( t < 0 )continue;// breakif ( t >= height )break;// for each kernel columnfor ( j = -radius; j <= radius; j++ ){t = x + j;// skip columnif ( t < 0 )continue;if ( t < width ){p = &src[i * nStride + j * 3];intensity = (int)( 0.2125 * (*p) + 0.7154 * (*(p+1))) + 0.0721 * (*(p+2));intensities[intensity] ++;// redred[intensity]		+= *p;// greengreen[intensity]	+= *(p+1);// blueblue[intensity]		+= *(p+2);}}}do{intensity = (rand()+1)%255;}while (intensities[intensity] == 0);// set destination pixel*dst = (unsigned char)( red[intensity] / intensities[intensity] );*(dst+1) = (unsigned char)( green[intensity] / intensities[intensity] );*(dst+2) = (unsigned char)( blue[intensity] / intensities[intensity] );}src += offset;dst += offset;}
}

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