[C++] Convert Raw format data to Bmp image

1. Bitmap structure

        Raw format data generally records the original information of the camera or camera sensor, which is an unprocessed original image file, while Bmp format data generally has a file header and information header in a specified format, so a bitmap file header needs to be added when converting As well as the information header, the defined structure is as follows:

typedef struct {
	WORD    bfType;//文件类型，必须是0x424D,即字符“BM”  
	DWORD   bfSize;//文件大小  
	WORD    bfReserved1;//保留字  
	WORD    bfReserved2;//保留字  
	DWORD   bfOffBits;//从文件头到实际位图数据的偏移字节数  
} BITMAPFILEHEADER;//位图文件头

typedef struct {
	DWORD     	 biSize;//信息头大小  
	LONG       biWidth;//图像宽度  
	LONG       biHeight;//图像高度  
	WORD       biPlanes;//位平面数，必须为1  
	WORD       biBitCount;//每像素位数  
	DWORD      biCompression;//压缩类型  
	DWORD      biSizeImage;//压缩图像大小字节数  
	LONG       biXPelsPerMeter;//水平分辨率  
	LONG       biYPelsPerMeter;//垂直分辨率  
	DWORD      biClrUsed;//位图实际用到的色彩数  
	DWORD      biClrImportant;//本位图中重要的色彩数
}BITMAPINFOHEADER;//位图信息头

2. Generate bitmap

void saveBITmap(int simple, int line, unsigned char *pData, char* filename)
{
	const int height = line;
	const int width = simple;
	long int size = height * width * 3;
	//double x,y;

	//生成文件头
	BITMAPFILEHEADER fileHeader;
	fileHeader.bfType = 0X4d42;
	fileHeader.bfReserved1 = 0;
	fileHeader.bfReserved2 = 0;
	fileHeader.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + size;
	fileHeader.bfOffBits = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

	//生成信息头
	BITMAPINFOHEADER bitmapHeader = { 0 };
	bitmapHeader.biSize = sizeof(BITMAPINFOHEADER);
	bitmapHeader.biHeight = -height;
	bitmapHeader.biWidth = width;
	bitmapHeader.biPlanes = 1;
	bitmapHeader.biBitCount = 24;
	bitmapHeader.biSizeImage = size;
	bitmapHeader.biCompression = 0; //BI_RGB  

	//保存数据
	FILE *fp2 = fopen(filename, "wb");
	if (!fp2) {
		return;
	}
	fwrite(&fileHeader, 1, sizeof(BITMAPFILEHEADER), fp2);
	fwrite(&bitmapHeader, 1, sizeof(BITMAPINFOHEADER), fp2);
	fwrite(pData, 1, size, fp2);
	fclose(fp2);

}

3. Writing the main function

	FILE *fp = NULL;
	static	BYTE raw_all[samples*lines*bands * 2];
	static	BYTE raw_data[samples*lines*bands];//定义为全局变量，防止出现局部变量过大产生bug
	BYTE *ptr;

	if ((fp = fopen("XXX.raw", "rb")) == NULL)
		return 0;

	ptr = (BYTE*)malloc(samples*lines*bands*sizeof(BYTE) * 2);
	for (int i = 0; i<samples*lines*bands * 2; i++)
	{
		fread(ptr, 1, 1, fp);
		raw_all[i] = *ptr;
	}

	for (int i = 0, j = 0; i<samples*lines*bands * 2; i += 2)
	{
		raw_data[j] = raw_all[i];
		j = j + 1;
	}
	static struct {
		BYTE B;
		BYTE G;
		BYTE R;
	} pRGB[lines][samples];
	for (int i = 0; i<lines; i++)
	{
		for (int j = 0; j<samples; j++)
		{
			BYTE a = raw_data[i*bands*samples + j];
			pRGB[i][j].R = pRGB[i][j].G = pRGB[i][j].B = a;
		}
	}
	saveBITmap(samples, lines, (BYTE*)pRGB, "XXX.bmp");
	free(ptr);
	return 0;