图像滤镜的一些加速和改进－－笔记

来源：互联网发布：曼朗网络编辑：程序博客网时间：2024/06/03 21:12

滤镜有很多开源代码包，imageshop,tinyimage,还有安卓的源码包，看过安卓的源码包，感觉还有很大的提升空间．

http://blog.csdn.net/jingwen3699/article/details/7770287　　这个博客有介绍，看看你就知道，至少针对图像遍历像素有很多加速的方法可用．

列出我整理出的速度最快的几个，基于opencv

/*adjust brightness and contract查找表 */void cast_LUT(const cv::Mat& src, cv::Mat& dst,unsigned char(&r_lookup)[256],unsigned char(&g_lookup)[256],                 unsigned char(&b_lookup)[256],IMAGE_CHANNELMODE mode){    uchar* srcData = src.data;    if(dst.empty()){    dst.create(src.size(),src.type());    }    uchar* dstData = dst.data;    int size = src.rows * src.cols * 3;    switch (mode){    case IMAGE_CHANEL_RGB:    {//经测试，这种遍历像素的方法时最快的，而且比较安全 for (int i = 0; i < size-3; i+=3)            {                dstData[i] = b_lookup[srcData[i]];                dstData[i+1] = g_lookup[srcData[i+1]];                dstData[i+2] = r_lookup[srcData[i+2]];        }         break;    }    case IMAGE_CHANEL_B:    {        for (int i = 0; i < size-3; i+=3)            {                dstData[i] = b_lookup[srcData[i]];        }        break;    }    case IMAGE_CHANEL_G:    {        for (int i = 0; i < size-3; i+=3)            {                dstData[i] = g_lookup[srcData[i+1]];        }        break;    }    case IMAGE_CHANEL_R:    {        for (int i = 0; i < size-3; i+=3)            {                dstData[i] = r_lookup[srcData[i+2]];        }        break;    }    }}

//这个是利用opencv里的ＬＵＴ查找表来实现的亮度和对比度调节void adjustBrightContract(const cv::Mat &src, cv::Mat &dst, float brightFactor, float contractFactor){    IMAGE_ASSERT_VOID(brightFactor >= -1.0 && brightFactor <= 1.0);    IMAGE_ASSERT_VOID(contractFactor >= -1.0 && contractFactor <= 1.0);    float delta = 1 + brightFactor;    float beta = 1 + contractFactor;    cv::Mat lookup(1,256,CV_8UC1);    uchar* pData = lookup.data;//生成查找表 for(int i = 0;i < 256;i++)    {        pData[i] = cv::saturate_cast<uchar>(i * delta);//bright        pData[i] = cv::saturate_cast<uchar>(thresholdc + (i - thresholdc) * beta);//contract    }    cv::LUT(src,lookup,dst);}//接下来时自动色阶的void adjustcolorLevel(cv::Mat& src,cv::Mat& dst,int blackThreshold,int whiteThreshold,float gamma,IMAGE_CHANNELMODE mode){    IMAGE_ASSERT_VOID(blackThreshold>= 0 && whiteThreshold>blackThreshold && whiteThreshold<=255);    IMAGE_ASSERT_VOID(gamma >= 0.0 && gamma <= 10.0);     unsigned char lookup[256];   // cv::Mat lookup(1,256,CV_8UC1);    uchar*pData = lookup;    //smaller than blackThreshold will be set to 0    for (int i = 0; i < blackThreshold; i ++)    {        pData[i] = 0;    }   //between using gamma correct    float ig = (gamma == 0.0) ? 0.0 : 1 / gamma;    float threshold = (float)(whiteThreshold - blackThreshold);    for (int i = blackThreshold; i < whiteThreshold; i++)    {        pData[i] = cv::saturate_cast<uchar>( pow((i-blackThreshold)/threshold,ig)*255);    }   //big than whiteThreshold will be set to 255    for (int i = whiteThreshold; i < 256; i++)    {        pData[i] = 255;    }//自己写的ＬＵＴ cast_LUT(src,dst,lookup,lookup,lookup,mode);    //cv::LUT(src,lookup,dst);}

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