我正在编写CUDA程序，将模糊效果添加到BMP文件中。我编写了在CPU上执行此操作的程序，现在我正在尝试将代码转换为CUDA。这是我想要在CUDA上工作的功能：
void blur(bitmap_header* hp, unsigned char *data)
{
int xx,yy,x,y, avgB, avgG, avgR, ile;
int blurSize = 5;
for(xx = 0; xx < hp->width; xx++)
{
for(yy = 0; yy < hp->height; yy++)
{
avgB = avgG = avgR = 0;
ile = 0;
for(x = xx; x < hp->width && x < xx + blurSize; x++)
{
for(y = yy; y < hp->height && y < yy + blurSize; y++)
{
avgB += data[x*3 + y*hp->width*3 + 0];
avgG += data[x*3 + y*hp->width*3 + 1];
avgR += data[x*3 + y*hp->width*3 + 2];
ile++;
}
}
avgB = avgB / ile;
avgG = avgG / ile;
avgR = avgR / ile;
data[xx*3 + yy*hp->width*3 + 0] = avgB;
data[xx*3 + yy*hp->width*3 + 1] = avgG;
data[xx*3 + yy*hp->width*3 + 2] = avgR;
}
}
}
如何将此功能转换为在CUDA设备上运行？ 每个教程只涵盖一个for循环并使用
int i = threadIdx.x
我之前关于此计划的问题： Blur effect on bitmap using C
修改
CUDA编辑的完整代码：
#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
#pragma pack(push,1)
/* Windows 3.x bitmap file header */
typedef struct {
char filetype[2]; /* magic - always 'B' 'M' */
unsigned int filesize;
short reserved1;
short reserved2;
unsigned int dataoffset; /* offset in bytes to actual bitmap data */
} file_header;
/* Windows 3.x bitmap full header, including file header */
typedef struct {
file_header fileheader;
unsigned int headersize;
int width;
int height;
short planes;
short bitsperpixel; /* we only support the value 24 here */
unsigned int compression; /* we do not support compression */
unsigned int bitmapsize;
int horizontalres;
int verticalres;
unsigned int numcolors;
unsigned int importantcolors;
} bitmap_header;
#pragma pack(pop)
__global__ void blur(bitmap_header* hp, unsigned char *data)
{
int xx,yy,x,y, avgB, avgG, avgR, ile;
int blurSize = 5;
xx = blockIdy.y * blockDim.y + threadIdx.y;
yy = blockIdx.x * blockDim.x + threadIdx.x;
if(xx >= hp->width || yy >= hp->height)
return;
avgB = avgG = avgR = 0;
ile = 0;
for(x = xx; x < hp->width && x < xx + blurSize; x++)
{
for(y = yy; y < hp->height && y < yy + blurSize; y++)
{
avgB += data[x*3 + y*hp->width*3 + 0];
avgG += data[x*3 + y*hp->width*3 + 1];
avgR += data[x*3 + y*hp->width*3 + 2];
ile++;
}
}
avgB = avgB / ile;
avgG = avgG / ile;
avgR = avgR / ile;
data[xx*3 + yy*hp->width*3 + 0] = avgB;
data[xx*3 + yy*hp->width*3 + 1] = avgG;
data[xx*3 + yy*hp->width*3 + 2] = avgR;
}
int filter(char* input, char *output)
{
//variable dec:
FILE *fp,*out;
bitmap_header* hp;
bitmap_header* d_hp;
unsigned char *data;
unsigned char *d_data;
//Open input file:
fp = fopen(input, "r");
if(fp==NULL)
return 1;
//Read the input file headers:
hp=(bitmap_header*)malloc(sizeof(bitmap_header));
cudaMalloc( &d_hp, (sizeof(bitmap_header));
if(hp==NULL)
return 1;
fread(hp, sizeof(bitmap_header), 1, fp);
cudaMemcpy(d_hp, &hp, (sizeof(bitmap_header), cudaMemcpyHostToDevice);
//Read the data of the image:
data = (unsigned char*)malloc(sizeof(char)*hp->bitmapsize);
cudaMalloc( &d_data, (sizeof(char)*hp->bitmapsize));
fseek(fp,sizeof(char)*hp->fileheader.dataoffset,SEEK_SET);
fread(data,sizeof(char),hp->bitmapsize, fp);
cudaMemcpy(d_data, &data, (sizeof(char)*hp->bitmapsize), cudaMemcpyHostToDevice);
dim3 block(16,16);
dim3 grid ( (hp->height + 15)/16, (hp->width + 15)/16 );
blur<<<grid,block>>>(d_hp, d_data);
cudaMemcpy(data, d_data, (sizeof(char)*hp->bitmapsize), cudaMemcpyDeviceToHost);
//Open output file:
out = fopen(output, "wb");
if(out==NULL)
{
fclose(fp);
free(hp);
free(data);
cudaFree(d_data);
cudaFree(d_hp);
return 1;
}
fwrite(hp,sizeof(char),sizeof(bitmap_header),out);
fseek(out,sizeof(char)*hp->fileheader.dataoffset,SEEK_SET);
fwrite(data,sizeof(char),hp->bitmapsize,out);
fclose(fp);
fclose(out);
free(hp);
free(data);
cudaFree(d_data);
cudaFree(d_hp);
return 0;
}
int main(int argc, char* argv[])
{
int frames;
int frame = 1;
char path[100000];
system("rd /s/q temp");
system("mkdir temp");
system("cls");
printf("Zapis wszystkich klatek do folderu temp.\n");
system("ffmpeg.exe -i test.mp4 -r 29.970 -vcodec bmp temp/%d.bmp");
printf("Ile jest klatek w folderze temp?\n");
scanf("%d", &frames);
for(frame = 1;frame<=frames;frame++)
{
sprintf(path,"temp\\%d.bmp",frame);
printf("Nakladam filtr na ");
printf(path);
printf("\n");
filter(path,path);
}
system("cls");
printf("Wszystkie klatki do filmu mp4.\n");
system("ffmpeg -r 29.970 -i temp/%d.bmp -c:v libx264 -preset slow -crf 21 temp/out.mp4");
system("cls");
printf("Wyciecie dzwieku z filmu do mp3\n");
system("ffmpeg -i test.mp4 -vn -ar 44100 -ac 2 -ab 192 -f wav temp/sound.wav");
system("cls");
printf("Polaczenie mp3 z mp4.\n");
system("ffmpeg -i temp/sound.wav -i temp/out.mp4 final.mp4");
system("cls");
printf("Delete ");
system("rd /s temp");
system("pause");
return 0;
}
完整错误列表：
Warning 1 warning : The 'compute_10' and 'sm_10' architectures are deprecated, and may be removed in a future release. C:\Users\Karpińscy\documents\visual studio 2012\Projects\blur\blur\nvcc blur
Error 2 error : identifier "blockIdy" is undefined C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
Error 3 error : expected a ")" C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
Warning 4 warning : expression has no effect C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
Error 5 error : expected a ")" C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
Error 6 error : too few arguments in function call C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
Error 7 error MSB3721: The command ""C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v6.0\bin\nvcc.exe" -gencode=arch=compute_10,code=\"sm_10,compute_10\" --use-local-env --cl-version 2012 -ccbin "C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\bin" -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v6.0\include" -I"C:\Program Files\NVIDIA GPU Computing Toolkit\CUDA\v6.0\include" -G -maxrregcount=0 --machine 32 --compile -cudart static -I -g -DWIN32 -D_DEBUG -D_CONSOLE -D_MBCS -Xcompiler "/EHsc /W3 /nologo /Od /Zi /RTC1 /MDd " -o Debug\kernel.cu.obj "C:\Users\Karpińscy\documents\visual studio 2012\Projects\blur\blur\kernel.cu"" exited with code 2. C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\V110\BuildCustomizations\CUDA 6.0.targets 597 9 blur
8 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 33 1 blur
9 IntelliSense: expected a ';' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 33 12 blur
10 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 56 4 blur
11 IntelliSense: expected a ';' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 56 9 blur
12 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 57 4 blur
13 IntelliSense: expected a ';' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 57 7 blur
14 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 58 3 blur
15 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 62 2 blur
16 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 63 2 blur
17 IntelliSense: identifier "xx" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 65 7 blur
18 IntelliSense: identifier "yy" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 65 14 blur
19 IntelliSense: identifier "avgB" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 65 36 blur
20 IntelliSense: identifier "xx" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 66 7 blur
21 IntelliSense: identifier "yy" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 66 14 blur
22 IntelliSense: identifier "xx" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 67 7 blur
23 IntelliSense: identifier "yy" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 67 14 blur
24 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 68 1 blur
25 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 94 5 blur
26 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 95 2 blur
27 IntelliSense: identifier "d_data" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 95 15 blur
28 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 95 21 blur
29 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 97 5 blur
30 IntelliSense: identifier "fp" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 97 11 blur
31 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 97 13 blur
32 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 98 5 blur
33 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 98 15 blur
34 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 99 2 blur
35 IntelliSense: identifier "d_data" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 99 13 blur
36 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 99 19 blur
37 IntelliSense: identifier "dim3" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 102 2 blur
38 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 102 15 blur
39 IntelliSense: identifier "dim3" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 103 2 blur
40 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 103 34 blur
41 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 105 2 blur
42 IntelliSense: expected a ';' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 105 6 blur
43 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 106 2 blur
44 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 106 17 blur
45 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 109 2 blur
46 IntelliSense: identifier "output" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 109 14 blur
47 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 110 2 blur
48 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 122 5 blur
49 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 122 14 blur
50 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 123 5 blur
51 IntelliSense: expected a ')' c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 123 16 blur
52 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 125 5 blur
53 IntelliSense: identifier "fp" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 125 12 blur
54 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 126 5 blur
55 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 127 5 blur
56 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 128 5 blur
57 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 130 2 blur
58 IntelliSense: identifier "d_data" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 130 11 blur
59 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 131 2 blur
60 IntelliSense: identifier "d_hp" is undefined c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 131 11 blur
61 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 132 5 blur
62 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 133 1 blur
63 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 158 2 blur
64 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 161 2 blur
65 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 162 2 blur
66 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 164 2 blur
67 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 165 2 blur
68 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 166 2 blur
69 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 168 2 blur
70 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 169 2 blur
71 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 170 2 blur
72 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 172 2 blur
73 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 173 2 blur
74 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 174 2 blur
75 IntelliSense: this declaration has no storage class or type specifier c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 175 2 blur
76 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 177 5 blur
77 IntelliSense: expected a declaration c:\Users\Karpińscy\Documents\Visual Studio 2012\Projects\blur\blur\kernel.cu 178 1 blur
答案 0 :(得分：5)
您的代码中存在相当多的语法错误。真的，他们与CUDA没有任何关系。也许您应该提高基本的C编码技能并理解如何解释编译器错误。
这一行：
cudaMalloc( &d_hp, (sizeof(bitmap_header));
缺少一个近括号。您无法看到，并且您也无法找出指示该错误的编译器错误？
Error 3 error : expected a ")" C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
在cuda中，没有内置变量blockIdy。也许你的意思是blockIdx.y？
Error 2 error : identifier "blockIdy" is undefined C:\Users\Karpi˝scy\documents\visual studio 2012\Projects\blur\blur\kernel.cu blur
此行的另一个编译错误：
cudaMemcpy(d_hp, &hp, (sizeof(bitmap_header), cudaMemcpyHostToDevice);
应该是这样的：
cudaMemcpy(d_hp, &hp, sizeof(bitmap_header), cudaMemcpyHostToDevice);
如果在修复这些编译错误后仍需要帮助，请使用完整但简单代码发布一个新问题，该代码不依赖于从文件中读取图像。只需创建一个简单的测试用例并使用它来验证内核。添加我提到的错误检查，并使用cuda-memcheck运行您的代码。如果你拒绝做这些事情，我无法帮助你。
答案 1 :(得分：1)
有一种名为 prefix sum 的方法，需要预先计算沿两个轴的运行总和矩阵。这可以非常有效地完成。一旦有了这个矩阵，就可以通过前缀和矩阵中四个值的线性组合计算O（1）中任意补丁（子矩阵）的和/平均值。
这里有一个关于它的帖子：How to process a integer matrix to find the average for the elements of any sub-rectangle in O(1)?
最后一步是迭代输入图像并将值设置为局部平均值。
与bluring的不同观点如下：使用简单的方形滤镜（或内核）convolve你的图像。在SO和网络上有关于在CUDA中实现2D卷积的多个例子。