CUDA卷积操作—使用constant memory实现高斯滤波

本文介绍了一种利用CUDA进行高斯滤波的方法,并详细展示了如何通过GPU加速卷积运算,对比了GPU与CPU实现的代码差异。

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先转载一篇CUDA卷积的实现,对比一下GPU与CPU中的代码有什么不同:

原文地址:CUDA卷积操作—使用constant memory实现高斯滤波

高斯滤波就是使用高斯模板和图片进行卷积运算,高斯函数及模板如下图所示:
这里写图片描述

卷积前后的效果图如下:

这里写图片描述

constant memory的使用及CUDA编程的相关内容,在代码注释中有详细介绍。
GPU代码如下所示:

#include "cuda_runtime.h"  
#include "device_launch_parameters.h"  

#include <stdio.h>  
#include "Windows.h"  
#include <math.h>  
#include<iostream>  
using namespace std;  

#define BLOCKDIM_X      16  
#define BLOCKDIM_Y      16  

#define GRIDDIM_X       256  
#define GRIDDIM_Y       256  
#define MASK_WIDTH      5  

__constant__ int d_const_Gaussian[MASK_WIDTH*MASK_WIDTH]; //分配常数存储器  

unsigned char *readBmp(char *bmpName, int *width, int *height, int *byteCount);  
bool saveBmp(char *bmpName, unsigned char *imgBuf, int width, int height, int byteCount);  
static __global__ void kernel_GaussianFilt(int width,int height,int byteCount,unsigned char *d_src_imgbuf,unsigned char *d_guassian_imgbuf);  

void main()  
{  
    //查看显卡配置  
    struct cudaDeviceProp pror;  
    cudaGetDeviceProperties(&pror,0);  
    cout<<"maxThreadsPerBlock="<<pror.maxThreadsPerBlock<<endl;  

    long start, end;  
    long time = 0;   

    //CUDA计时函数  
    start = GetTickCount();  
    cudaEvent_t startt,stop; //CUDA计时机制  
    cudaEventCreate(&startt);  
    cudaEventCreate(&stop);  
    cudaEventRecord(startt,0);  

    unsigned char *h_src_imgbuf;  //图像指针  
    int width, height, byteCount;  
    char rootPath1[]="C:\\Users\\a404\\Desktop\\测试图片\\";  
    char readPath[1024];  
    int frame=1;  
    for (int k=1;k<=frame;k++)  
    {  
        sprintf(readPath, "%s%d.bmp", rootPath1, k);  
        h_src_imgbuf=readBmp(readPath, &width, &height, &byteCount);  

        int size1=width*height *byteCount*sizeof(unsigned char);  
        int size2=width*height *sizeof(unsigned char);  

        //输出图像内存-host端    
        unsigned char *h_guassian_imgbuf=new unsigned char[width*height*byteCount];  

        //分配显存空间  
        unsigned char *d_src_imgbuf;  
        unsigned char *d_guassian_imgbuf;  

        cudaMalloc((void**)&d_src_imgbuf, size1);  
        cudaMalloc((void**)&d_guassian_imgbuf, size1);  

        //把数据从Host传到Device  
        cudaMemcpy(d_src_imgbuf, h_src_imgbuf, size1, cudaMemcpyHostToDevice);  

        //将高斯模板传入constant memory  
        int Gaussian[25] = {1,4,7,4,1,  
                            4,16,26,16,4,  
                            7,26,41,26,7,  
                            4,16,26,16,4,  
                            1,4,7,4,1};//总和为273  
        cudaMemcpyToSymbol(d_const_Gaussian, Gaussian, 25 * sizeof(int));  

        int bx = ceil((double)width/BLOCKDIM_X); //网格和块的分配  
        int by = ceil((double)height/BLOCKDIM_Y);  

        if(bx > GRIDDIM_X) bx = GRIDDIM_X;  
        if(by > GRIDDIM_Y) by = GRIDDIM_Y;  

        dim3 grid(bx, by);//网格的结构  
        dim3 block(BLOCKDIM_X, BLOCKDIM_Y);//块的结构  

        //kernel--高斯滤波  
        kernel_GaussianFilt<<<grid, block>>>(width,height,byteCount,d_src_imgbuf,d_guassian_imgbuf);  
        cudaMemcpy(h_guassian_imgbuf, d_guassian_imgbuf,size1, cudaMemcpyDeviceToHost);//数据传回主机端  

        char rootPath2[]="C:\\Users\\a404\\Desktop\\测试结果\\";  
        char writePath[1024];  
        sprintf(writePath, "%s%d.bmp", rootPath2, k);  
        saveBmp(writePath, h_guassian_imgbuf, width, height, byteCount);  

        //输出进度展示  
        cout<<k<<"  "<<((float)k/frame)*100<<"%"<<endl;  

        //释放内存  
        cudaFree(d_src_imgbuf);   
        cudaFree(d_guassian_imgbuf);  

        delete []h_src_imgbuf;  
        delete []h_guassian_imgbuf;  
    }  
    end = GetTickCount();  
    InterlockedExchangeAdd(&time, end - start);  
    cout << "Total time GPU:";  
    cout << time << endl;  
    int x;  
    cin>>x;  
}  

static __global__ void kernel_GaussianFilt(int width,int height,int byteCount,unsigned char *d_src_imgbuf,unsigned char *d_dst_imgbuf)  
{  
    const int tix = blockDim.x * blockIdx.x + threadIdx.x;  
    const int tiy = blockDim.y * blockIdx.y + threadIdx.y;  

    const int threadTotalX = blockDim.x * gridDim.x;  
    const int threadTotalY = blockDim.y * gridDim.y;  

    for(int ix = tix; ix < height; ix += threadTotalX)  
        for(int iy = tiy; iy < width; iy += threadTotalY)  
        {   
            for(int k=0;k<byteCount;k++)  
            {  
                int sum=0;//临时值  
                int tempPixelValue=0;  
                for (int m=-2;m<=2;m++)  
                {  
                    for (int n=-2;n<=2;n++)  
                    {  
                        //边界处理,幽灵元素赋值为零  
                        if (ix+m<0||iy+n<0||ix+m>=height||iy+n>=width)                        
                            tempPixelValue=0;                          
                        else                          
                            tempPixelValue=*(d_src_imgbuf+(ix+m)*width*byteCount+(iy+n)*byteCount+k);                             
                        sum+=tempPixelValue*d_const_Gaussian[(m+2)*5+n+2];  
                    }  
                }  

                if (sum/273<0)   
                    *(d_dst_imgbuf+(ix)*width*byteCount+(iy)*byteCount+k)=0;  
                else if(sum/273>255)    
                    *(d_dst_imgbuf+(ix)*width*byteCount+(iy)*byteCount+k)=255;  
                else    
                    *(d_dst_imgbuf+(ix)*width*byteCount+(iy)*byteCount+k)=sum/273;        
            }  
        }  
}  

unsigned char *readBmp(char *bmpName, int *width, int *height, int *byteCount)  
{  
    //打开文件  
    FILE *fp=fopen(bmpName,"rb");  
    if(fp==0) return 0;  
    //跳过文件头  
    fseek(fp, sizeof(BITMAPFILEHEADER),0);  

    //读入信息头  
    int w, h, b;  
    BITMAPINFOHEADER head;  
    fread(&head, sizeof(BITMAPINFOHEADER), 1,fp);   
    w = head.biWidth;  
    h = head.biHeight;  
    b = head.biBitCount/8;  
    int lineByte=(w * b+3)/4*4; //每行的字节数为4的倍数  

    //跳过颜色表 (颜色表的大小为1024)(彩色图像并没有颜色表,不需要这一步)  
    if(b==1)  
        fseek(fp, 1024,1);  

    //图像数据  
    unsigned char *imgBuf=new unsigned char[w * h * b];  
    for(int i=0;i<h;i++)  
    {  
        fread(imgBuf+i*w*b,w*b, 1,fp);  
        fseek(fp, lineByte-w*b, 1);  
    }  
    fclose(fp);  

    *width=w,  *height=h, *byteCount=b;  

    return imgBuf;  
}  


bool saveBmp(char *bmpName, unsigned char *imgBuf, int width, int height, int byteCount)  
{  
    if(!imgBuf)  
        return 0;  

    //灰度图像颜色表空间1024,彩色图像没有颜色表  
    int palettesize=0;  
    if(byteCount==1) palettesize=1024;  

    //一行象素字节数为4的倍数  
    int lineByte=(width * byteCount+3)/4*4;  

    FILE *fp=fopen(bmpName,"wb");  
    if(fp==0) return 0;  

    //填写文件头  
    BITMAPFILEHEADER fileHead;  
    fileHead.bfType = 0x4D42;  
    fileHead.bfSize=   
        sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+ palettesize + lineByte*height;  
    fileHead.bfReserved1 = 0;  
    fileHead.bfReserved2 = 0;  
    fileHead.bfOffBits=54+palettesize;  
    fwrite(&fileHead, sizeof(BITMAPFILEHEADER),1, fp);  

    // 填写信息头  
    BITMAPINFOHEADER head;   
    head.biBitCount=byteCount*8;  
    head.biClrImportant=0;  
    head.biClrUsed=0;  
    head.biCompression=0;  
    head.biHeight=height;  
    head.biPlanes=1;  
    head.biSize=40;  
    head.biSizeImage=lineByte*height;  
    head.biWidth=width;  
    head.biXPelsPerMeter=0;  
    head.biYPelsPerMeter=0;  
    fwrite(&head, sizeof(BITMAPINFOHEADER),1, fp);  

    //颜色表拷贝    
    if(palettesize==1024)  
    {  
        unsigned char palette[1024];  
        for(int i=0;i<256;i++)  
        {  
            *(palette+i*4+0)=i;  
            *(palette+i*4+1)=i;  
            *(palette+i*4+2)=i;  
            *(palette+i*4+3)=0;       
        }  
        fwrite(palette, 1024,1, fp);  
    }  

    //准备数据并写文件  
    unsigned char *buf=new unsigned char[height*lineByte];  
    for(int i=0;i<height;i++)  
    {  
        for(int j=0;j<width*byteCount; j++)  
            *(buf+i*lineByte+j)=*(imgBuf+i*width*byteCount+j);  
    }  
    fwrite(buf, height*lineByte, 1, fp);  

    delete []buf;  

    fclose(fp);  

    return 1;  
}  

附录:高斯滤波CPU代码

#include "stdio.h"  
#include "Windows.h"  
#include <iostream>  
using namespace std;  

unsigned char *readBmp(char *bmpName, int *width, int *height, int *byteCount); //读入图像  
bool saveBmp(char *bmpName, unsigned char *imgBuf, int width, int height, int byteCount); //保存图像  
void GaussianFilt(int width,int height,int byteCount,int Gaussian[][5],unsigned char *gray_imgbuf,unsigned char *guassian_imgbuf); //高斯滤波  

void main()  
{  
    //计时函数  
    long start, end;  
    long time = 0;   
    start = GetTickCount();  

    unsigned char *src_imgbuf; //图像指针  
    int width, height, byteCount;  
    char rootPath1[]="C:\\Users\\a404\\Desktop\\测试图片\\";  
    char readPath[1024];  
    int frame=300;  //读入图像副数  
    for (int i=1;i<=frame;i++)  
    {  
        sprintf(readPath, "%s%d.bmp", rootPath1, i);  
        src_imgbuf=readBmp(readPath, &width, &height, &byteCount);  
        //printf("宽=%d,高=%d,字节=%d\n",width, height, byteCount);  

        //读入高斯模糊模板  
        int Gaussian_mask[5][5]={{1,4,7,4,1},{4,16,26,16,4},{7,26,41,26,7},{4,16,26,16,4},{1,4,7,4,1}};//总和为273  

        //输出图像内存分配    
        unsigned char *guassian_imgbuf=new unsigned char[width*height*byteCount];  

        //对原图高斯模糊  
        GaussianFilt(width,height,byteCount,Gaussian_mask,src_imgbuf,guassian_imgbuf);  

        char rootPath2[]="C:\\Users\\a404\\Desktop\\";  
        char writePath[1024];  
        sprintf(writePath, "%s%d.bmp", rootPath2, i);  

        saveBmp(writePath, guassian_imgbuf, width, height, byteCount);  

        cout<<i<<"  "<<((float)i/frame)*100<<"%"<<endl;  
        delete []src_imgbuf;  
        delete []guassian_imgbuf;  
    }  
    end = GetTickCount();  
    InterlockedExchangeAdd(&time, end - start);  
    cout << "Total time CPU:";  
    cout << time << endl;  
    int x;  
    cin>>x;  
}  

void GaussianFilt(int width,int height,int byteCount,int Gaussian[][5],unsigned char *src_imgbuf,unsigned char *guassian_imgbuf)  
{  
    //高斯模糊处理 5层循环处理  
    for(int i=0;i<height;i++)  
    {  
        for(int j=0;j<width;j++)  
        {  
            for(int k=0;k<byteCount;k++)  
            {  
                int sum=0;//临时值  
                int tempPixelValue=0;  
                for (int m=-2;m<=2;m++)  
                {  
                    for (int n=-2;n<=2;n++)  
                    {  
                        //边界处理,幽灵元素赋值为零  
                        if (i+m<0||j+n<0||i+m>=height||j+n>=width)                        
                            tempPixelValue=0;                          
                        else                          
                            tempPixelValue=*(src_imgbuf+(i+m)*width*byteCount+(j+n)*byteCount+k);     
                        //tempPixelValue=*(gray_imgbuf+(i+m)*width+(j+n)+k);      
                        sum+=tempPixelValue*Gaussian[m+2][n+2];  
                    }  
                }  
                //tempPixelValue=*(src_imgbuf+(i)*width*byteCount+(j)*byteCount+k);  
                if (sum/273<0)   
                    *(guassian_imgbuf+i*width*byteCount+j*byteCount+k)=0;  
                else if(sum/273>255)    
                    *(guassian_imgbuf+i*width*byteCount+j*byteCount+k)=255;  
                else    
                    *(guassian_imgbuf+i*width*byteCount+j*byteCount+k)=sum/273;       
            }  
        }  
    }  
}  

//给定一个图像文件及其路径,读入图像数据。   
unsigned char *readBmp(char *bmpName, int *width, int *height, int *byteCount)  
{  
    //打开文件,  
    FILE *fp=fopen(bmpName,"rb");  
    if(fp==0) return 0;  
    //跳过文件头  
    fseek(fp, sizeof(BITMAPFILEHEADER),0);  

    //读入信息头  
    int w, h, b;  
    BITMAPINFOHEADER head;  
    fread(&head, sizeof(BITMAPINFOHEADER), 1,fp);   
    w = head.biWidth;  
    h = head.biHeight;  
    b = head.biBitCount/8;  
    int lineByte=(w * b+3)/4*4; //每行的字节数为4的倍数  

    //跳过颜色表 (颜色表的大小为1024)(彩色图像并没有颜色表,不需要这一步)  
    if(b==1)  
        fseek(fp, 1024,1);  

    //图像数据  
    unsigned char *imgBuf=new unsigned char[w * h * b];  
    for(int i=0;i<h;i++)  
    {  
        fread(imgBuf+i*w*b,w*b, 1,fp);  
        fseek(fp, lineByte-w*b, 1);  
    }  
    fclose(fp);  

    *width=w,  *height=h, *byteCount=b;  

    return imgBuf;  
}  


bool saveBmp(char *bmpName, unsigned char *imgBuf, int width, int height, int byteCount)  
{  
    if(!imgBuf)  
        return 0;  

    //灰度图像颜色表空间1024,彩色图像没有颜色表  
    int palettesize=0;  
    if(byteCount==1) palettesize=1024;  

    //一行象素字节数为4的倍数  
    int lineByte=(width * byteCount+3)/4*4;  

    FILE *fp=fopen(bmpName,"wb");  
    if(fp==0) return 0;  

    //填写文件头  
    BITMAPFILEHEADER fileHead;  
    fileHead.bfType = 0x4D42;  
    fileHead.bfSize=   
        sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+ palettesize + lineByte*height;  
    fileHead.bfReserved1 = 0;  
    fileHead.bfReserved2 = 0;  
    fileHead.bfOffBits=54+palettesize;  
    fwrite(&fileHead, sizeof(BITMAPFILEHEADER),1, fp);  

    // 填写信息头  
    BITMAPINFOHEADER head;   
    head.biBitCount=byteCount*8;  
    head.biClrImportant=0;  
    head.biClrUsed=0;  
    head.biCompression=0;  
    head.biHeight=height;  
    head.biPlanes=1;  
    head.biSize=40;  
    head.biSizeImage=lineByte*height;  
    head.biWidth=width;  
    head.biXPelsPerMeter=0;  
    head.biYPelsPerMeter=0;  
    fwrite(&head, sizeof(BITMAPINFOHEADER),1, fp);  

    //颜色表拷贝    
    if(palettesize==1024)  
    {  
        unsigned char palette[1024];  
        for(int i=0;i<256;i++)  
        {  
            *(palette+i*4+0)=i;  
            *(palette+i*4+1)=i;  
            *(palette+i*4+2)=i;  
            *(palette+i*4+3)=0;       
        }  
        fwrite(palette, 1024,1, fp);  
    }  

    //准备数据并写文件  
    unsigned char *buf=new unsigned char[height*lineByte];  
    for(int i=0;i<height;i++)  
    {  
        for(int j=0;j<width*byteCount; j++)  
            *(buf+i*lineByte+j)=*(imgBuf+i*width*byteCount+j);  
    }  
    fwrite(buf, height*lineByte, 1, fp);  

    delete []buf;  

    fclose(fp);  

    return 1;  
}  
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