純C語言實作BMP影像的讀、寫

純C語言實作BMP影像的讀、寫

對于剛接觸數字影像的同學，應該都有一個疑問，如何把一個BMP格式的影像用純C語言讀入呢，我相信這也是數字影像處理的第一步，如果有幸看到這篇檔案，我就有幸的成為你數字影像處理路上的第一盞明燈！

了解BMP的構成

    這就是BMP影像的理論知識，有個大概的了解就行，最主要的是從理論到實踐！！！

廢話不多說，直接上干貨，

代碼

定義頭檔案為“bmp.h”，定義read_bmp函式為讀函式，write_bmp函式為寫函式
讀bmp圖

#include <stdlib.h>
#include <math.h>
#include <Windows.h>
#include "bmp.h"
/*存盤原圖的像素寬度高度和位圖深度*/
FILE* fpbmp;
FILE* fpout;
unsigned char* fpBmpHeader;   //位圖頭
unsigned char* fpFileHeader;  //位圖資訊
RGBQUAD* pColorTable;         //BMP 調色板
int read_bmp(const char* path, unsigned char *pBmpBuf,int *Width,int *Height,int * bitCount)
{
	fpbmp = fopen(path, "rb");//path為影像路徑
	unsigned short s;
	fread(&s, 1, 2, fpbmp);
	//判斷讀入的影像是否為BMP圖  字串"BM"=19778
	if (s == 19778)
	{
		printf("Open bmp success!!!\n");
	}
	else
	{
		printf("Open bmp fail!!!\n");
		return -1;
	}
	fseek(fpbmp, 0, SEEK_SET);
	BITMAPFILEHEADER fileHead;
	fread(&fileHead, sizeof(BITMAPFILEHEADER), 1, fpbmp);

	BITMAPINFOHEADER infoHead;
	fread(&infoHead, sizeof(BITMAPINFOHEADER), 1, fpbmp);

	*Width = infoHead.biWidth;//影像的寬
	*Height = infoHead.biHeight;//影像的高
	*bitCount = infoHead.biBitCount;
	int lineByte = (*Width * *bitCount / 8 + 3) / 4 * 4;
	fseek(fpbmp, sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD),SEEK_SET);
	fread(pBmpBuf, lineByte * *Height, 1, fpbmp);//pBmpBuf為影像的RGB資料，也是我們將要處理的資料
	return 0;
}

寫BMP圖

int write_bmp(unsigned char* img, int* Width, int* Height, int* bitCount)
{
	fpout = fopen("out.bmp", "wb+");
	if (fpbmp == NULL)
	{
		printf("read bmp failed!!!\n");
		return -1;
	}
	int lineByte = (*Width * *bitCount / 8 + 3) / 4 * 4;
	if (lineByte == 0)
	{
		printf("err");
		return -1;
	}
	fpFileHeader = new unsigned char[(sizeof(BITMAPFILEHEADER))];
	fseek(fpbmp, 0, SEEK_SET);  //定位原圖 偏移位置
	fseek(fpout, 0, SEEK_SET);  //定位新圖 偏移位置
	fread(fpFileHeader, 1, sizeof(BITMAPFILEHEADER), fpbmp);
	fwrite(fpFileHeader, 1, sizeof(BITMAPFILEHEADER), fpout);


	/*復制原圖中 位圖 資訊到新影像*/
	fpBmpHeader = new unsigned char[(sizeof(BITMAPINFOHEADER))];
	fseek(fpbmp, sizeof(BITMAPFILEHEADER), SEEK_SET);
	fseek(fpout, sizeof(BITMAPFILEHEADER), SEEK_SET);
	fread(fpBmpHeader, 1, sizeof(BITMAPINFOHEADER), fpbmp);
	fwrite(fpBmpHeader, 1, sizeof(BITMAPINFOHEADER), fpout);

	/*Copy 調色板 info*/
	pColorTable = new RGBQUAD[256];
	fseek(fpbmp, sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER), SEEK_SET);
	fseek(fpout, sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER), SEEK_SET);
	fread(pColorTable, sizeof(RGBQUAD), 256, fpbmp);
	fwrite(pColorTable, sizeof(RGBQUAD), 256, fpout);

	fseek(fpout, sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + sizeof(RGBQUAD), SEEK_SET);
	fwrite(img, lineByte * *Height, sizeof(char), fpout);
	fclose(fpout);
	fclose(fpbmp);
	return 0;
}

main函式呼叫

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <Windows.h>
#include "bmp.h"

int main()
{
	int width, height, bitCount = 0;
	unsigned char* pBmpBuf = (unsigned char*)malloc(1000 * 1000 * 3);//申請空間
	const char* path = "D:\\test\\read_bmp_image\\1-B.bmp";//圖的路徑
	read_bmp(path, pBmpBuf, &width, &height, &bitCount);
	write_bmp(pBmpBuf, &width, &height, &bitCount);
}

總結，將read_bmp函式回傳的pBmpBuf引數，賦值給write_bmp函式的img引數，就實作了BMP圖從讀到寫的全部程序，有興趣的同學動手實踐下，會有意向不到的識訓，
注：在線轉換BMP圖的網址，可以將任何格式的照片轉換為BMP格式，親測好用，鏈接奉上BMP影像轉換網址