将RGB纯数据保存生成bmp图片（位图）

在图像算法测试中，验证RGB数据是否正确通常将它生成位图，然后打开图片来验证。

//BMP文件头（14字节）
typedef struct                       /**** BMP file header structure ****/
{
    unsigned int   bfSize;           /* Size of file */
    unsigned short bfReserved1;      /* Reserved */
    unsigned short bfReserved2;      /* ... */  
    unsigned int   bfOffBits;        /* Offset to bitmap data */
} MyBITMAPFILEHEADER;

//位图信息头（40字节）
typedef struct                       /**** BMP file info structure ****/
{
    unsigned int   biSize;           /* Size of info header */
    int            biWidth;          /* Width of image */
    int            biHeight;         /* Height of image */
    unsigned short biPlanes;         /* Number of color planes */
    unsigned short biBitCount;       /* Number of bits per pixel */
    unsigned int   biCompression;    /* Type of compression to use */
    unsigned int   biSizeImage;      /* Size of image data */
    int            biXPelsPerMeter;  /* X pixels per meter */
    int            biYPelsPerMeter;  /* Y pixels per meter */
    unsigned int   biClrUsed;        /* Number of colors used */
    unsigned int   biClrImportant;   /* Number of important colors */
} MyBITMAPINFOHEADER;

void MySaveBmp(const char *filename,unsigned char *rgbbuf,int width,int height)
{
    MyBITMAPFILEHEADER bfh;
    MyBITMAPINFOHEADER bih;
    /* Magic number for file. It does not fit in the header structure due to alignment requirements, so put it outside */
    unsigned short bfType=0x4d42;
    bfh.bfReserved1 = 0;
    bfh.bfReserved2 = 0;
    bfh.bfSize = 2+sizeof(MyBITMAPFILEHEADER) + sizeof(MyBITMAPINFOHEADER)+width*height*2;
    bfh.bfOffBits = 0x36;

    bih.biSize = sizeof(MyBITMAPINFOHEADER);
    bih.biWidth = width;
    bih.biHeight = height;
    bih.biPlanes = 1;
    bih.biBitCount = 24;
    bih.biCompression = 0;
    bih.biSizeImage = 0;
    bih.biXPelsPerMeter = 5000;
    bih.biYPelsPerMeter = 5000;
    bih.biClrUsed = 0;
    bih.biClrImportant = 0;

    printf("filename=%s \n", filename);
    FILE *file = fopen(filename, "wb");
    if (!file)
    {
        printf("Could not write file\n");
        return;
    }

    /*Write headers*/
    fwrite(&bfType,sizeof(bfType),1,file);
    fwrite(&bfh,sizeof(bfh),1, file);
    fwrite(&bih,sizeof(bih),1, file);

    fwrite(rgbbuf,width*height*3,1,file);
    fclose(file);
}