linu下C语言之BMP图片操作编程(下)

前面提高了一个将BMP左转的程序，右转其实也是类似的操作，就不写了，这节，我们来实现，将一张BMP图进行灰度处理，代码贴上：

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>

#define  RGB(r,g,b)    		((r+g+b)/3)

typedef  unsigned char  U8 ;
typedef  unsigned short U16 ;
typedef  unsigned int   U32 ; 

#pragma  pack(1)
struct bmp_header
{
	//bmp header
	U8  Signatue[2] ;   // B  M
	U32 FileSize ;     //文件大小
	U16 Reserv1 ;
	U16 Reserv2 ;
	U32 FileOffset ;   //文件头偏移量

	//DIB header
	U32 DIBHeaderSize ; //DIB头大小
	U32 ImageWidth   ;  //文件宽度
	U32 ImageHight   ;  //文件高度
	U16 Planes       ;
	U16 BPP          ;  //每个相素点的位数
	U32 Compression  ;
	U32 ImageSize    ;  //图文件大小
	U32 XPPM ;
	U32 YPPM ;
	U32 CCT ;
	U32 ICC ;
};
#pragma  pack()

int main(int argc , char **argv)
{
	if(argc != 4)
		return -1 ; 

	int fd ;
	int dest_fd ;
	fd = open(argv[1] , O_RDONLY);
	if(-1 == fd)
	{
		perror("open bmp file fail");
		return -2 ;
	}

	dest_fd = open( argv[2] , O_RDWR | O_CREAT|O_TRUNC , 0777);
	if(dest_fd < 0 )
	{
		perror("open rgb565 fail");
		return -3 ;
	}
	int value = atoi(argv[3]);

	struct bmp_header  header ; 

	int ret ; 

	ret = read(fd , &header , sizeof(struct bmp_header));

	printf(" Signatue[0]      : %c  \n " , header.Signatue[0]  );
	printf(" Signatue[1]      : %c  \n " , header.Signatue[1]  );
	printf(" FileSize         : %d  \n " , header.FileSize     );
	printf(" Reserv1          : %d  \n " , header.Reserv1      );
	printf(" Reserv2          : %d  \n " , header.Reserv2      );
	printf(" FileOffset       : %d  \n " , header.FileOffset   );
	printf(" DIBHeaderSize    : %d  \n " , header.DIBHeaderSize);
	printf(" ImageWidth       : %d  \n " , header.ImageWidth   );
	printf(" ImageHight       : %d  \n " , header.ImageHight   );
	printf(" Planes           : %d  \n " , header.Planes       );
	printf(" BPP              : %d  \n " , header.BPP          );
	printf(" Compression      : %d  \n " , header.Compression  );
	printf(" ImageSize        : %d  \n " , header.ImageSize    );
	printf(" XPPM             : %d  \n " , header.XPPM         );
	printf(" YPPM             : %d  \n " , header.YPPM         );
	printf(" CCT              : %d  \n " , header.CCT          );
	printf(" ICC              : %d  \n " , header.ICC          );

	char buffer[header.ImageSize] ; 

	read(fd , buffer , header.ImageSize);

	close(fd);

	//改变地方

	write(dest_fd , &header , sizeof(struct bmp_header));

	int row , col ;
	char *p = NULL ; 

	for(row = 0 ; row < 10 ; row++)
	{
		for(col = 0 ; col < 10 ; col++)
		{
			p = buffer + (row * 800 + col)*3 ;
			*p = 255;
			*(p+1)=255;
			*(p+2)=255;
		}
	}

	char data ;
	for(row = 0 ; row < 480  ; row++)
	{
		for(col = 0 ; col < 800 ; col++)
		{
			p =( buffer+(row*800 + col)*3);
			data = RGB((unsigned char)(*(p+2)) , (unsigned char)(*(p+1)) ,
			(unsigned char )(*(p)));
			if(data < value)
			{
			*p = 0;
			*(p+1)=0;
			*(p+2)=0;
			}
			else
			{
			*p = data;
			*(p+1)=data;
			*(p+2)=data;
			}
			write(dest_fd , p , 3);
		}
	}

	close(dest_fd);

	return 0 ;
}