bmp图像读取

最近写了个bmp图像读取，将图片转化为单一颜色的小程序，直接上代码，仅供参考。
1.先上测试函数（基本一看就知道流程）

/**********************************************************************************************
Author: Lihaowei
Date: 2015-04-2
version:0.0
Discriptions:
        1.This file is used to test "bitMapfunction.c"  (load a bitmap,convert bitmap to single-color
          image (R||G||B),and write a new bitmap).

************************************************************************************************/

#include <stdio.h>
#include <stdlib.h>
#include "../include/bitMap.h"


void main()
{

    char filename_in[20] = "input.bmp";
    char filename_out1[20] = "output_r.bmp";
    char filename_out2[20] = "output_g.bmp";
    char filename_out3[20] = "output_b.bmp";

    BITMAPFILE* bitmap1,*bitmap2,*bitmap3;
    bitmap1 = loadBitmap(filename_in);
    bitmap2 = loadBitmap(filename_in);
    bitmap3 = loadBitmap(filename_in);

    toSingleColor(bitmap1,'R');
    toSingleColor(bitmap2,'G');
    toSingleColor(bitmap3,'B');
    writeBmp(filename_out1,bitmap1);
    writeBmp(filename_out2,bitmap2);
    writeBmp(filename_out3,bitmap3);
    free(bitmap1);
    free(bitmap2);
    free(bitmap3);
}

2.头文件

/***********************************bitMap.h***********************************************************
Author: Lihaowei
Date: 2015-04-2
version:0.0
Discriptions:

************************************************************************************************/
typedef unsigned char  u8;
typedef unsigned short u16;
typedef unsigned int   u32;
#pragma pack(1)
/*bitmap file header,size:14 bytes*/
typedef struct tagBITMAPFILEHEADER
{   
    u16 bfType; 
    u32 bfSize;
    u16 bfReserved1;
    u16 bfReserved2;
    u32 bfOffBits;
}BITMAPFILEHEADER;
/*bitmap information header,size:40 bytes*/
typedef struct tagBITMAPINFOHEADER
{
    u32 biSize;
    u32 biWidth;
    u32 biHeight;
    u16 biPlanes;
    u16 biBitCount;
    u32 biCompression;
    u32 biSizeImage;
    u32 biXPelsPerMeter;
    u32 biYPelsPerMeter;
    u32 biClrUsed;
    u32 biClrImportant;
}BITMAPINFOHEADER;
/*color palette,size:4 bytes*/
typedef struct tagRGBQUAD
{
    u8 rgbBlue;
    u8 rgbGreen;
    u8 rgbRed;
    u8 rgbReserved;
}RGBQUAD;

typedef struct tagBITMAP
{
    BITMAPFILEHEADER bfHeader;
    BITMAPINFOHEADER biHeader;
    RGBQUAD bmpColors[1];
    u8* imageData;
    u8* dataR;
    u8* dataG;
    u8* dataB;

}BITMAPFILE;

BITMAPFILE * loadBitmap(char *path);
void writeBmp(char *path ,BITMAPFILE *bitmap);
void toSingleColor(BITMAPFILE *bitmap,char color);//color='R'||'G'||'B'

2.功能源文件

/************************************bitMapfunction.c**********************************************************
Author: Lihaowei
Date: 2015-04-2
version:0.0
Discriptions:
        1.This file offer some functions to load a bitmap,convert bitmap to single-color
          image (R||G||B),and to write a new bitmap.
        2.To use these function , please include "bitMap.h" in your program 
************************************************************************************************/


#include <stdio.h>
#include <stdlib.h>
#include "../include/bitMap.h"



/*fuction:void toSingleColor(BITMAPFILE *bitmap,char color); */
/*convert to single-color image*/

/***********************************************************************************************/
void toSingleColor(BITMAPFILE *bitmap,char color)
{
    int i,j;
    int colorid=0;
    switch(color)
    {
        case 'R':   colorid = 0;
                break;
        case 'G':   colorid = 2;
                break;
        case 'B':   colorid = 1;
                break;
        default:    colorid = 1;
    }

    for(i =0; i < bitmap->biHeader.biHeight; i++)
    {

        for(j = 0; j < bitmap->biHeader.biWidth; j++)
        {

                *(bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+colorid) = 0;
                *(bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+(colorid+1)%3) = 0;
                /*if(*(bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+(colorid+2)%3) > 50)
                    (bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+(colorid+2)%3) = 255;
                  else
                    (bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+(colorid+2)%3) = 0;   */

        }
    }
}


/***********************************************************************************************/


/*fuction:BITMAPFILE * loadBitmap(char *path); */
/*load a bitmap*/
/***********************************************************************************************/
BITMAPFILE * loadBitmap(char *path)
{
    int i,j;
    BITMAPFILE * bitmap={0};
    FILE *bmfp=fopen(path,"r+");
    if( !bmfp )
    {
        printf("open %s error!\n",path);
        exit(0);
    }
    bitmap = (BITMAPFILE*)malloc(sizeof(BITMAPFILE));


    /********************************test the file to judge whether it is a bitmap**************************/
    unsigned short bfType = 0;

    fseek(bmfp, 0L, SEEK_SET);
    fread(&bfType, sizeof(char), 2, bmfp);
    if (0x4D42!= bfType)
    {
            printf("This is not a bmp file!!!\n");
            exit(1);
    }
    /*******************************************************************************************************/


    /*********************************read the Header of the bitmap*****************************************/
    /*read file information header*/

    fseek(bmfp, 0L, SEEK_SET);
    fread(&(bitmap->bfHeader), sizeof(unsigned char), sizeof(BITMAPFILEHEADER), bmfp);


    /*read bmp information header*/
    fread(&(bitmap->biHeader), 1 ,sizeof(BITMAPINFOHEADER), bmfp);


    /*read RGBQUAD information*/

    /******************************************************************************************************/

    /********************************read image data*******************************************************/
    /*read image data*/

    if(bitmap->biHeader.biBitCount == 24)
    {

        unsigned int width = bitmap->biHeader.biWidth;
        unsigned int height = bitmap->biHeader.biHeight;

        bitmap->imageData = (unsigned char*)malloc(sizeof(unsigned char)*width*3*height);
        bitmap->dataR     = (unsigned char*)malloc(sizeof(unsigned char)*width * height);
        bitmap->dataG     = (unsigned char*)malloc(sizeof(unsigned char)*width * height);
        bitmap->dataB     = (unsigned char*)malloc(sizeof(unsigned char)*width * height);
        fseek(bmfp,bitmap->bfHeader.bfOffBits,SEEK_SET);
        /*read imageData */
        fread(bitmap->imageData, sizeof(unsigned char), width*3*height, bmfp);
        for(i =0; i < bitmap->biHeader.biHeight; i++)
        {

            for(j = 0; j <bitmap->biHeader.biWidth; j++)
            {

                /*seperate R G B data from imageData */
                *(bitmap->dataB+(bitmap->biHeader.biHeight-i-1)*(bitmap->biHeader.biWidth)+j) =
                         *(bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j));

                *(bitmap->dataG+(bitmap->biHeader.biHeight-i-1)*(bitmap->biHeader.biWidth)+j) =
                         *(bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+1);

                *(bitmap->dataR+(bitmap->biHeader.biHeight-i-1)*(bitmap->biHeader.biWidth)+j) =
                         *(bitmap->imageData+3*((bitmap->biHeader.biWidth)*i+j)+2);


            }
        }
    }
    else
    {
        printf("Only handle 24bit per pixel bitMap\n");
        exit(0);
    }

    /******************************************************************************************************/

    /****************************write to dat file*********************************************************/
    /*write to dat file*/

    FILE* fpDataBmp1,*fpDataBmp2,*fpDataBmp3;
    /* New a file to save the data matrix */
    if((fpDataBmp1 = fopen("data_R.dat","w+")) == NULL)
    {
            printf("Failed to construct file bmpData_R.dat!");
            exit(1);
    }
    if((fpDataBmp2 = fopen("data_G.dat","w+")) == NULL)
    {
            printf("Failed to construct file bmpData_R.dat!");
            exit(1);
    }
    if((fpDataBmp3 = fopen("data_B.dat","w+")) == NULL)
    {
            printf("Failed to construct file bmpData_R.dat!");
            exit(1);
    }

    for(i =0; i < bitmap->biHeader.biHeight; i++)
    {
        fprintf(fpDataBmp1,"line %d :\n",i);
        fprintf(fpDataBmp2,"line %d :\n",i);
        fprintf(fpDataBmp3,"line %d :\n",i);
        for(j = 0; j < bitmap->biHeader.biWidth; j++)
        {

            fprintf(fpDataBmp1, "%-3d ", *(bitmap->dataR+(bitmap->biHeader.biHeight-i-1)*(bitmap->biHeader.biWidth)+j));
            fprintf(fpDataBmp2, "%-3d ", *(bitmap->dataG+(bitmap->biHeader.biHeight-i-1)*(bitmap->biHeader.biWidth)+j));
            fprintf(fpDataBmp3, "%-3d ", *(bitmap->dataB+(bitmap->biHeader.biHeight-i-1)*(bitmap->biHeader.biWidth)+j));

            if ((j+1)%32 == 0)
            {
                fprintf(fpDataBmp1, "\n");
                fprintf(fpDataBmp2, "\n");
                fprintf(fpDataBmp3, "\n");
            }
        }
    }
    fclose(fpDataBmp1);
    fclose(fpDataBmp2);
    fclose(fpDataBmp3);

    fclose(bmfp);
    return bitmap;
}
/***********************************************************************************************/



/*fuction:void writeBmp(char *path ,BITMAPFILE *bitmap); */


/*write a new bitmap*/
/***********************************************************************************************/
void writeBmp(char *path ,BITMAPFILE *bitmap)
{
    unsigned int width = bitmap->biHeader.biWidth;
    unsigned int height = bitmap->biHeader.biHeight;
    FILE *bmfp=fopen(path,"w+");
    if(bmfp == NULL)  
        {  
            printf("fopen %s failed !\n",path);  
            exit(1);  
        }  
    /***************************write image header****************************************/
    /*write file information header*/
    fseek(bmfp, 0L, SEEK_SET);
    fwrite(&(bitmap->bfHeader),sizeof(unsigned char), sizeof(BITMAPFILEHEADER), bmfp);


    /*write bmp information header*/
    fwrite(&(bitmap->biHeader), 1 ,sizeof(BITMAPINFOHEADER), bmfp);

    /*write RGBQUAD information*/
    /**************************************************************************************/

    /*write data*/
    fseek(bmfp, bitmap->bfHeader.bfOffBits, SEEK_SET);
    fwrite(bitmap->imageData,sizeof(unsigned char),width*3*height,bmfp);

}
/***********************************************************************************************/

一些原理性的细节之后再写博客补充吧。而且这个程序在数据对齐方面没注意，只支持24位真彩色图的处理。