bmp_24_16.c

24BMP图转16

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <fcntl.h>
#include "bmp_head.h"

int main()
{
	int fd_r;
	int fd_w;

	char buf_head[55];

	unsigned char buf_24[3];
	unsigned char buf_16[2];	

	unsigned int bmp_24 = 0;
	unsigned short bmp_16 = 0;

//	info_bmp("a.bmp");

	if((fd_r = open("a.bmp", O_RDONLY)) < 0)
	{
		printf("open a.bmp error\n");
		exit(0);
	}
	if((fd_w = open("b.bmp", O_CREAT | O_TRUNC | O_WRONLY)) < 0)
	{
		printf("open b.bmp error\n");
		exit(0);
	}
	
	read(fd_r, buf_head, 54);
	write(fd_w, buf_head, 54);

	while(read(fd_r, buf_24, 3) > 0)
	{
		bmp_16 = 0;
		bmp_16 |= ((buf_24[2] >> 3) & 0x1f);
		bmp_16 <<= 6;
		bmp_16 |= ((buf_24[1] >> 2) & 0x3f);
		bmp_16 <<= 5;
		bmp_16 |= ((buf_24[0] >> 3) & 0x1f);

		buf_16[0] = (char)bmp_16;
		buf_16[1] = (char)(bmp_16 >> 8);

		write(fd_w, buf_16, 2);
	}	

	return 0;
}