RGB数据保存为BMP图片
一、BMP文件由文件头、位图信息头、颜色信息和图形数据四部分组成
1、BMP文件头(14字节)
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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;
2、位图信息头(40字节)
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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;
3、颜色表
颜色表用于说明位图中的颜色,它有若干个表项,每一个表项是一个RGBQUAD类型的结构,定义一种颜色。RGBQUAD结构的定义如下:
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typedefstructtagRGBQUAD{
BYTErgbBlue;//蓝色的亮度(值范围为0-255)
BYTErgbGreen;//绿色的亮度(值范围为0-255)
BYTErgbRed;//红色的亮度(值范围为0-255)
BYTErgbReserved;//保留,必须为0
}RGBQUAD;
颜色表中的RGBQUAD结构数据的个数由biBitCount来确定:当biBitCount=1,4,8时,分别为2,16,256个表项;当biBitCount=24时,没有颜色表项。
4、位图数据
位图数据记录了位图的每一个像素值,记录顺序是在扫描行内是从左到右,扫描行之间是从下到上。位图的一个像素值所占的字节数:
当biBitCount=1时,8个像素占1个字节;
当biBitCount=4时,2个像素占1个字节;
当biBitCount=8时,1个像素占1个字节;
当biBitCount=24时,1个像素占3个字节,按顺序分别为B,G,R;
二、将rgb数据保存为bmp图片的方法
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void CDecVideoFilter::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(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER)+width*height*3;
bfh.bfOffBits = 0x36;
bih.biSize = sizeof(BITMAPINFOHEADER);
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;
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);
}
三、显示
四、代码
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