代码如下：

#include<stdio.h> #include<malloc.h> #include<stdlib.h> #pragma pack(1) typedef struct tagBITMAPFILEHEADER { unsigned char bfType[2];//文件格式 unsigned long bfSize;//文件大小 unsigned short bfReserved1;//保留 unsigned short bfReserved2; unsigned long bfOffBits; //DIB数据在文件中的偏移量 }fileHeader; #pragma pack() /* 位图数据信息结构 */ #pragma pack(1) typedef struct tagBITMAPINFOHEADER { unsigned long biSize;//该结构的大小 long biWidth;//文件宽度 long biHeight;//文件高度 unsigned short biPlanes;//平面数 unsigned short biBitCount;//颜色位数 unsigned long biCompression;//压缩类型 unsigned long biSizeImage;//DIB数据区大小 long biXPixPerMeter; long biYPixPerMeter; unsigned long biClrUsed;//多少颜色索引表 unsigned long biClrImporant;//多少重要颜色 }fileInfo; #pragma pack() /* 调色板结构 */ #pragma pack(1) typedef struct tagRGBQUAD { unsigned char rgbBlue; //蓝色分量亮度 unsigned char rgbGreen;//绿色分量亮度 unsigned char rgbRed;//红色分量亮度 unsigned char rgbReserved; }rgbq; #pragma pack() int main() { FILE *fp1 = fopen("C:\\Users\\Administrator\\Desktop\\data\\bmp\\image.bmp", "rb+"); if (fp1 == NULL) { printf("打开文件fp1失败"); exit(0); } FILE *fp2 = fopen("C:\\Users\\Administrator\\Desktop\\data\\bmp\\imageGray.bmp", "wb"); if (fp1 == NULL) { printf("打开文件fp2失败"); exit(0); } fileHeader * fh; fileInfo * fi; fh = (fileHeader *)malloc(sizeof(fileHeader)); fi = (fileInfo *)malloc(sizeof(fileInfo)); //读取位图头结构和信息头 fread(fh, sizeof(fileHeader), 1, fp1); fread(fi, sizeof(fileInfo), 1, fp1); printf("\\\\\\\\\\\\\\\\\\\\原始图片信息\\\\\\\\\\\\\\\\\\\\\\\\\\\n"); printf("bmp文件头：\n"); printf("bfSize:%d\n", fh->bfSize); printf("bfOffBits:%d\n", fh->bfOffBits); printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n"); printf("bmp信息头\n"); printf("结构体长度：%d \n", fi->biSize); printf("位图宽度：%d \n", fi->biWidth); printf("位图高度：%d \n", fi->biHeight); printf("位图平面数：%d \n", fi->biPlanes); printf("颜色位数：%d \n", fi->biBitCount); printf("压缩方式：%d \n", fi->biCompression); printf("实际位图数据占用的字节数：%d \n", fi->biSizeImage); printf("X方向分辨率：%d \n", fi->biXPixPerMeter); printf("Y方向分辨率：%d \n", fi->biYPixPerMeter); printf("使用的颜色数：%d \n", fi->biClrUsed); printf("重要颜色数：%d \n", fi->biClrImporant); printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n"); //修改信息头 fi->biBitCount = 8; //fi->biSizeImage = ((fi->biWidth * 3 + 3) / 4) * 4 * fi->biHeight; fi->biSizeImage = fi->biHeight*fi->biWidth; //修改文件头 fh->bfOffBits = sizeof(fileHeader) + sizeof(fileInfo) + 256 * sizeof(rgbq); fh->bfSize = fh->bfOffBits + fi->biSizeImage; printf("\\\\\\\\\\\\\\\\\\\\修改后的图片信息\\\\\\\\\\\\\\\\\\\\\\\\\\\n"); printf("bmp文件头：\n"); printf("bfSize:%d\n", fh->bfSize); printf("bfOffBits:%d\n", fh->bfOffBits); printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n"); printf("bmp信息头\n"); printf("结构体长度：%d \n", fi->biSize); printf("位图宽度：%d \n", fi->biWidth); printf("位图高度：%d \n", fi->biHeight); printf("位图平面数：%d \n", fi->biPlanes); printf("颜色位数：%d \n", fi->biBitCount); printf("压缩方式：%d \n", fi->biCompression); printf("实际位图数据占用的字节数：%d \n", fi->biSizeImage); printf("X方向分辨率：%d \n", fi->biXPixPerMeter); printf("Y方向分辨率：%d \n", fi->biYPixPerMeter); printf("使用的颜色数：%d \n", fi->biClrUsed); printf("重要颜色数：%d \n", fi->biClrImporant); printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n"); //创建调色板 int i,j,k=0; rgbq *fq = (rgbq *)malloc(256 * sizeof(rgbq)); for (i = 0; i<256; i++) { fq[i].rgbBlue = fq[i].rgbGreen = fq[i].rgbRed = i; } //写入文件头、信息头、调色板 fwrite(fh, sizeof(fileHeader), 1, fp2); fwrite(fi, sizeof(fileInfo), 1, fp2); fwrite(fq, sizeof(rgbq), 256, fp2); //将位图信息转为灰度 //存储bmp一行的像素点 //unsigned char ImgData[900][3]; unsigned char ImgData[3000][3]; //将灰度图像存到一维数组中 //unsigned char grayData2[900]; unsigned char ImgData2[3000]; /* //错误的算法 for (i = 0; i < fi->biHeight; i++) { for (j = 0; j < (fi->biWidth * 3 + 3) / 4 * 4; j++) { for (k = 0; k < 3; k++) { fread(&ImgData[j][k], 1, 1, fp1); } } for (j = 0; j < (fi->biWidth + 3) / 4 * 4; j++) { ImgData2[j] = int((float)ImgData[j][0] * 0.114 + (float)ImgData[j][1] * 0.587 + (float)ImgData[j][2] * 0.299); } //将灰度图信息写入 fwrite(ImgData2, j, 1, fp2); } */ /* //正确的算法(1) for (i = 0; i<fi->biHeight; i++) { for (j = 0; j<(fi->biWidth + 3) / 4 * 4; j++) { for (k = 0; k<3; k++) fread(&ImgData[j][k], 1, 1, fp1); } for (j = 0; j<(fi->biWidth + 3) / 4 * 4; j++) { ImgData2[j] = int((float)ImgData[j][0] * 0.114 + (float)ImgData[j][1] * 0.587 + (float)ImgData[j][2] * 0.299); } //将灰度图信息写入 fwrite(ImgData2, j, 1, fp2); } */ //正确算法（2） unsigned char * * bmp_data; bmp_data = new unsigned char*[fi->biHeight]; //声明一个指针数组 unsigned char *data288 = new unsigned char[fi->biHeight*fi->biWidth]; for (i = 0; i<fi->biHeight; i++) bmp_data[i] = new unsigned char[(fi->biWidth * 3 + 3) / 4 * 4]; //每个数组元素也是一个指针数组 for (i = 0; i<fi->biHeight; i++) for (j = 0; j<(fi->biWidth * 3 + 3) / 4 * 4; j++) fread(&bmp_data[i][j], 1, 1, fp1);//每次只读取一个字节，存入数组 for (i = 0; i<fi->biHeight; i++)//将24位真彩色转换成灰度图 for (j = 0; j<fi->biWidth; j++){ data288[fi->biWidth*i + j] = ((unsigned char)((float)bmp_data[i][3 * j] * 0.114 + (float)bmp_data[i][3 * j + 1] * 0.587 + (float)bmp_data[i][3 * j + 2] * 0.299)); } fwrite(data288, fi->biSizeImage, 1, fp2); free(fh); free(fi); free(fq); fclose(fp1); fclose(fp2); printf("success\n"); return 0; }