【原创】C语言读取BMP格式图片


BMP是英文Bitmap（位图）的简写，它是Windows操作系统中的标准图像文件格式，能够被多种Windows应用程序所支持。随着Windows操作系统的流行与丰富的Windows应用程序的开发，BMP位图格式理所当然地被广泛应用。这种格式的特点是包含的图像信息较丰富，几乎不进行压缩，但由此导致了它与生俱生来的缺点--占用磁盘空间过大。所以，目前BMP在单机上比较流行。


BMP文件格式分析
简介
BMP(Bitmap-File)图形文件是Windows采用的图形文件格式，在Windows环境下运行的所有图象处理软件都支持BMP图象文件格式。Windows系统内部各图像绘制操作都是以BMP为基础的。Windows 3.0以前的BMP图文件格式与显示设备有关，因此把这种BMP图象文件格式称为设备相关位图DDB(device-dependent bitmap)文件格式。Windows 3.0以后的BMP图象文件与显示设备无关，因此把这种BMP图象文件格式称为设备无关位图DIB(device-independent bitmap)格式（注：Windows 3.0以后，在系统中仍然存在DDB位图，象BitBlt()这种函数就是基于DDB位图的，只不过如果你想将图像以BMP格式保存到磁盘文件中时，微软极力推荐你以DIB格式保存），目的是为了让Windows能够在任何类型的显示设备上显示所存储的图象。BMP位图文件默认的文件扩展名是BMP或者bmp（有时它也会以.DIB或.RLE作扩展名）。


位图文件结构表
位图文件 位图文件头14 字节
位图信息头 40 字节
彩色表（调色板） 4N 字节
位图数据 x字节

构件详解：


位图文件头
位图文件头包含文件类型、文件大小、存放位置等信息。结构定义如下：


typedef struct tagBITMAPFILEHEADER
{
UNITbfType;
DWORDbfSize;
UINTbfReserved1;
UINTbfReserved2;
DWORDbfOffBits;
}BITMAPFILEHEADER;

其中：
bfType说明文件类型，在windows系统中为BM。
bfSize说明文件大小。
bfReserved1 bfReserved2 保留，设置为０。
bfOffBits 说明实际图形数据的偏移量。



位图信息头
位图信息头包含位图的大小、压缩类型、和颜色格式，结构定义如下：





typedef struct tagBITMAPINFOHEADER
{
DWORDbiSize;
LONGbiWidth;
LONGbiHeight;
WORDbiPlanes;
WORDbiBitCount;
DWORDbiCompression;
DWORDbiSizeImage;
LONGbiXPelsPerMerer;
LONGbiYPelsPerMerer;
DWORDbiClrUsed;
DWORDbiClrImportant;
}BITMAPINFOHEADER;

其中：
biSize说明BITMAPINFOHEADER结构所需字节数，在windows系统中为28h
biWidth说明图像宽度
biHeight说明图像高度
biPlanes为目标设备说明位面数，其值设为１
biBitCount每个像素的位数，单色位图为１，２５６色为８，２４bit为２４。
biCompression压缩说明，BI_RGB：无压缩，BI_RLE8：８位RLE压缩，BI_RLE4：４位RLE压缩
biSizeImage说明图像大小，如无压缩，可设为０
biXPelsPerMeter水平分辨率
biYPelsPerMeter垂直分辨率
biClrUsed 位图使用的颜色数
biImportant重要颜色数目



彩色表
彩色表包含的元素与位图所具有的颜色数目相同，像素颜色用结构RGBQUAD来表示：


typedef struct tagRGBQUAD
{
BYTErgbBlue;
BYTErgbGreen;
BYTErgbRed;
BYTErgbReserved;
}RGBQUAD;
其中：
rgbBlue指定蓝色强度
rgbGreen指定绿色强度
rgbRed指定红色强度
rgbReserved保留，设为０



位图数据
紧跟在彩色表后的是图像数据阵列，图像每一扫描行由连续的字节组成，扫描行由底向上存储，阵列中第一字节为左下角像素，最后一字节为右上角像素。



源代码1
【【原创】C语言读取BMP格式图片】

/* File name:bmpTest.c Description: Show all Info a bmp file has. including FileHeader Info, InfoHeader Info and Data Part. Reference: BMP图像数据的C语言读取源码 */#include "stdafx.h" //#include #include #define BITMAPFILEHEADERLENGTH 14// The bmp FileHeader length is 14 #define BM 19778// The ASCII code for BM/* Test the file is bmp file or not */ void bmpFileTest(FILE* fpbmp); /* To get the OffSet of header to data part */ void bmpHeaderPartLength(FILE* fpbmp); /* To get the width and height of the bmp file */ void BmpWidthHeight(FILE* fpbmp); /* Show bmp file tagBITMAPFILEHEADER info */ void bmpFileHeader(FILE* fpbmp); /* Show bmp file tagBITMAPINFOHEADER info */ void bmpInfoHeader(FILE* fpbmp); /* Show the Data Part of bmp file */ void bmpDataPart(FILE* fpbmp); unsigned int OffSet = 0; // OffSet from Header part to Data Part long BmpWidth = 0L; // The Width of the Data Part long BmpHeight = 0L; // The Height of the Data Partint main(int argc, char* argv[]) { /* Open bmp file */ //FILE *fpbmp = fopen("lena.bmp", "r+"); FILE *fpbmp = fopen("picture.bmp", "r+"); if (fpbmp == NULL) { fprintf(stderr, "Open lena.bmp failed!!!\n"); return 1; }bmpFileTest(fpbmp); //Test the file is bmp file or not bmpHeaderPartLength(fpbmp); //Get the length of Header Part BmpWidthHeight(fpbmp); //Get the width and width of the Data Part bmpFileHeader(fpbmp); //Show the FileHeader Information bmpInfoHeader(fpbmp); //Show the InfoHeader Information bmpDataPart(fpbmp); //Reserve the data to file fclose(fpbmp); return 0; }/* Test the file is bmp file or not */ void bmpFileTest(FILE* fpbmp) { unsigned short bfType = 0; fseek(fpbmp, 0L, SEEK_SET); fread(&bfType, sizeof(char), 2, fpbmp); if (BM != bfType) { fprintf(stderr, "This file is not bmp file.!!!\n"); exit(1); } }/* To get the OffSet of header to data part */ void bmpHeaderPartLength(FILE* fpbmp) { fseek(fpbmp, 10L, SEEK_SET); fread(&OffSet, sizeof(char), 4, fpbmp); //printf("The Header Part is of length %d.\n", OffSet); }/* To get the width and height of the bmp file */ void BmpWidthHeight(FILE* fpbmp) { fseek(fpbmp, 18L, SEEK_SET); fread(&BmpWidth, sizeof(char), 4, fpbmp); fread(&BmpHeight, sizeof(char), 4, fpbmp); //printf("The Width of the bmp file is %ld.\n", BmpWidth); //printf("The Height of the bmp file is %ld.\n", BmpHeight); }/* Show bmp file tagBITMAPFILEHEADER info */ void bmpFileHeader(FILE* fpbmp) { unsigned short bfType; //UNITbfType; unsigned intbfSize; //DWORDbfSize; unsigned short bfReserved1; //UINTbfReserved1; unsigned short bfReserved2; //UINTbfReserved2; unsigned intbfOffBits; //DWORDbfOffBits; fseek(fpbmp, 0L, SEEK_SET); fread(&bfType,sizeof(char), 2, fpbmp); fread(&bfSize,sizeof(char), 4, fpbmp); fread(&bfReserved1, sizeof(char), 2, fpbmp); fread(&bfReserved2, sizeof(char), 2, fpbmp); fread(&bfOffBits,sizeof(char), 4, fpbmp); printf("************************************************\n"); printf("*************tagBITMAPFILEHEADER info***********\n"); printf("************************************************\n"); printf("bfTypeis %d.\n", bfType); printf("bfSizeis %d.\n", bfSize); printf("bfReserved1is %d.\n", bfReserved1); printf("bfReserved2is %d.\n", bfReserved2); printf("bfOffBitsis %d.\n", bfOffBits); }/* Show bmp file tagBITMAPINFOHEADER info */ void bmpInfoHeader(FILE* fpbmp) { unsigned int biSize; // DWORDbiSize; longbiWidth; // LONGbiWidth; longbiHeight; // LONGbiHeight; unsigned int biPlanes; // WORDbiPlanes; unsigned int biBitCount; // WORDbiBitCount; unsigned int biCompression; // DWORDbiCompression; unsigned int biSizeImage; // DWORDbiSizeImage; longbiXPelsPerMerer; // LONGbiXPelsPerMerer; longbiYPelsPerMerer; // LONGbiYPelsPerMerer; unsigned int biClrUsed; // DWORDbiClrUsed; unsigned int biClrImportant; // DWORDbiClrImportant; fseek(fpbmp, 14L, SEEK_SET); fread(&biSize,sizeof(char), 4, fpbmp); fread(&biWidth,sizeof(char), 4, fpbmp); fread(&biHeight,sizeof(char), 4, fpbmp); fread(&biPlanes,sizeof(char), 4, fpbmp); fread(&biBitCount,sizeof(char), 4, fpbmp); fread(&biCompression,sizeof(char), 4, fpbmp); fread(&biSizeImage,sizeof(char), 4, fpbmp); fread(&biXPelsPerMerer, sizeof(char), 4, fpbmp); fread(&biYPelsPerMerer, sizeof(char), 4, fpbmp); fread(&biClrUsed,sizeof(char), 4, fpbmp); fread(&biClrImportant,sizeof(char), 4, fpbmp); printf("************************************************\n"); printf("*************tagBITMAPINFOHEADER info***********\n"); printf("************************************************\n"); printf("biSizeis %d. \n", biSize); printf("biWidthis %ld.\n", biWidth); printf("biHeightis %ld.\n", biHeight); printf("biPlanesis %d. \n", biPlanes); printf("biBitCountis %d. \n", biBitCount); printf("biCompressionis %d. \n", biCompression); printf("biSizeImageis %d. \n", biSizeImage); printf("biXPelsPerMereris %ld.\n", biXPelsPerMerer); printf("biYPelsPerMereris %ld.\n", biYPelsPerMerer); printf("biClrUsedis %d. \n", biClrUsed); printf("biClrImportantis %d. \n", biClrImportant); }/* Show the Data Part of bmp file */ void bmpDataPart(FILE* fpbmp) { int i, j; //unsigned char bmpPixel[BmpWidth][BmpHeight]; unsigned char bmpPixel[1000][1000]; //因为暂时还未找到好的方法，暂且长和宽都设为1000，如果图像的尺寸大于1000，则要重新设置unsigned char* bmpPixelTmp = NULL; FILE* fpDataBmp; /* New a file to save the data matrix */ if((fpDataBmp=fopen("bmpData.dat","w+")) == NULL) { fprintf(stderr, "Failed to construct file bmpData.dat.!!!"); exit(1); }fseek(fpbmp, OffSet, SEEK_SET); if ((bmpPixelTmp=(unsigned char*)malloc(sizeof(char)*BmpWidth*BmpHeight))==NULL) { fprintf(stderr, "Data allocation failed.!!!\n"); exit(1); } fread(bmpPixelTmp, sizeof(char), BmpWidth*BmpHeight, fpbmp); /* Read the data to Matrix and save it in file bmpData.dat */ for(i =0; i < BmpHeight; i++) { fprintf(fpDataBmp, "The data in line %-3d:\n", i+1); for(j = 0; j < BmpWidth; j++) { bmpPixel[i][j] = bmpPixelTmp[BmpWidth*(BmpHeight-1-i)+j]; //fwrite(&chartmp, sizeof(char), 1, fpDataBmp); fprintf(fpDataBmp, "%-3d ", bmpPixel[i][j]); if ((j+1)%32 == 0) { fprintf(fpDataBmp, "\n"); } } } /* Used to test the data read is true or false You can open the file using Matlab to compare the data */ //printf("bmpPixel[2][3]is %d.\n", bmpPixel[2][3]); //printf("bmpPixel[20][30] is %d.\n", bmpPixel[20][30]); free(bmpPixelTmp); fclose(fpDataBmp); }

// 读取图像2.cpp : Defines the entry point for the console application. //#include "stdafx.h" //#include #include #define BITMAPFILEHEADERLENGTH 14// The bmp FileHeader length is 14 #define BM 19778// The ASCII code for BM/* Test the file is bmp file or not */ void bmpFileTest(FILE* fpbmp); /* To get the OffSet of header to data part */ void bmpHeaderPartLength(FILE* fpbmp); /* To get the width and height of the bmp file */ void BmpWidthHeight(FILE* fpbmp); //get r,g,b data void bmpDataPart(FILE* fpbmp); // output data to corresponding txt file void bmpoutput(FILE *fpout); unsigned int OffSet = 0; // OffSet from Header part to Data Part long width ; // The Width of the Data Part long height ; // The Height of the Data Part unsigned char r[2000][2000],output_r[2000][2000]; unsigned char g[2000][2000],output_g[2000][2000]; unsigned char b[2000][2000],output_b[2000][2000]; int main(int argc, char* argv[]) { /* Open bmp file */ unsigned char *fp_temp; FILE *fpbmp; FILE *fpout; fpbmp= fopen("lena.bmp", "rb"); if (fpbmp == NULL) { printf("Open bmp failed!!!\n"); return 1; }fpout= fopen("out.bmp", "wb+"); if (fpout == NULL) { printf("Open out.bmp failed!!!\n"); return 1; }bmpFileTest(fpbmp); //Test the file is bmp file or not bmpHeaderPartLength(fpbmp); //Get the length of Header Part BmpWidthHeight(fpbmp); //Get the width and width of the Data Part // fseek(fpbmp, 0L, SEEK_SET); fseek(fpout, 0L, SEEK_SET); fp_temp=(unsigned char *)malloc(OffSet); fread(fp_temp, 1, OffSet, fpbmp); fwrite(fp_temp,1,OffSet,fpout); bmpDataPart(fpbmp); //Reserve the data to file /*如果您想对图片进行处理，请您再这里插入处理函数!!!!!!!!!!!!!!!!!! */ bmpoutput(fpout); fclose(fpbmp); fclose(fpout); return 0; }void bmpoutput(FILE* fpout) { int i, j=0; int stride; unsigned char* pixout=NULL; stride=(24*width+31)/8; stride=stride/4*4; pixout=(unsigned char *)malloc(stride); fseek(fpout, OffSet, SEEK_SET); for(j=0; j