C语言解析MNIST数据集

小编用C语言解析MNIST数据集，产生的图片是倒立着的。

数据集下载地址：http://yann.lecun.com/exdb/mnist/
小编解析的是测试集：t10k-images.idx3-ubyte
代码如下：
bmp.h

#ifndef BMP_H#define BMP_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()#endif

main

#include <stdio.h>#include <stdlib.h>#include <iostream>#include "bmp.h"using namespace std;#define SUM 10000int main(){    int a, num, size1, size2;    //用于存储一张手写体图片的位图信息    char image[28 * 28];    //用于存储产生的图片的名字    char name[100];    //10000张测试集    FILE *fp1 = fopen("C:\\Users\\Administrator\\Desktop\\data\\t10k-images.idx3-ubyte", "rb+");    if (fp1 == NULL)    {        //cout << "unable open file1" << endl;        //exit(1);        printf("unable open file2");    }    /*    //测试集的label    FILE *fp11 = fopen("C:\\Users\\Administrator\\Desktop\\data\\t10k-labels.idx1-ubyte", "rb+");    if (fp1 == NULL)    {        printf("unable open t10k-labels.idx1-ubyte");    }    else    {        //读取t10k-labels.idx1-ubyte的幻数、数量        fread(&a, sizeof(int), 1, fp11);        fread(&num, sizeof(int), 1, fp11);        //读取t10k-labels.idx1-ubyte的前28×28个label        fread(image, sizeof(char), 28 * 28, fp11);        printf("------------------label--------------------------------");        printf("a=%0x\n", a);        printf("num=%0x\n", num);        for (int i = 0; i < 28 * 28; i++)        {            printf("%d\t", image[i]);        }        printf("------------------label--------------------------------");    }    */    //读取字符集的幻数、数量、宽、高    fread(&a, sizeof(int), 1, fp1);    fread(&num, sizeof(int), 1, fp1);    fread(&size1, sizeof(int), 1, fp1);    fread(&size2, sizeof(int), 1, fp1);    /*    //打印字符集的幻数、数量、宽、高    printf("a=%0x\n", a);    printf("num=%0x\n", num);    printf("size1=%0x\n", size1);    printf("size2=%0x\n", size2);    for (int i = 0; i < 28 * 28; i++)    {        printf("%d\t", image[i]);    }    */    fileHeader fh;    fileInfo fi;    //编写信息头fi    fi.biSize = 40;    fi.biWidth = 28;    fi.biHeight = 28;    fi.biPlanes = 1;    fi.biBitCount = 8;    fi.biCompression = 0;    fi.biSizeImage = 28 * 28;    fi.biXPixPerMeter = 0;    fi.biYPixPerMeter = 0;    fi.biClrUsed = 0;    fi.biClrImporant = 0;    //编写文件头fh    fh.bfType[0] = 0x42;    fh.bfType[1] = 0x4D;    fh.bfOffBits = sizeof(fileHeader) + sizeof(fileInfo) + 256 * sizeof(rgbq);    fh.bfSize = fh.bfOffBits + fi.biSizeImage;    fh.bfReserved1 = 0;    fh.bfReserved2 = 0;    //创建调色板    rgbq *fq = (rgbq *)malloc(256 * sizeof(rgbq));    for (int i = 0; i<256; i++)    {        fq[i].rgbBlue = fq[i].rgbGreen = fq[i].rgbRed = i;    }    //创建要生成的数字图片    FILE *fp2 = fopen("C:\\Users\\Administrator\\Desktop\\data\\numbers.bmp", "wb");    if (fp2 == NULL)    {        printf("unable open file2");    }    for (int i = 1; i <= SUM; i++)    {        //创建一个BMP图片        sprintf(name, "C:\\Users\\Administrator\\Desktop\\data\\image\\%05d.bmp", i);        FILE *ftmp = fopen(name, "wb");        if (ftmp == NULL)            printf("Create %05d.bmp failure\n", i);        else        {            //读取一张图片的位图信息            fread(image, sizeof(char), 28 * 28, fp1);            //写文件头            fwrite(&fh, sizeof(fileHeader), 1, ftmp);            //写信息头            fwrite(&fi, sizeof(fileInfo), 1, ftmp);            //写调色板            fwrite(fq, sizeof(rgbq), 256, ftmp);            //写位图信息            fwrite(image, fi.biSizeImage, 1, ftmp);            fclose(ftmp);        }    }    fclose(fp1);    printf("------------------------------\n");    return 0;}

结果如下：