[C++知识库]c语言实现直方图均衡

#include<stdio.h>
#include<malloc.h>
#include<stdlib.h>
#include <math.h>
/*
位图头结构
*/
#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()
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()
{
    unsigned char ImgData2[640][640];
    unsigned char ImgData3[1000];
    int i, j, k;
    FILE * fpGray, * fpGrayAverage;
    fileHeader* fh;
    fileInfo* fi;
    rgbq* fq;
    char filename1[20], filename2[20];
    errno_t error;
    printf("输入图像文件名：");
    scanf_s("%s", filename1, 20);
    error = fopen_s(&fpGray, filename1, "rb+");
    if (error != 0)
    {
        printf("打开文件失败");
        exit(0);
    }
    printf("输出直方图均衡后图像文件名：");
    scanf_s("%s", filename2, 20);
    error = fopen_s(&fpGrayAverage, filename2, "wb");
    if (error != 0)
    {
        printf("创建文件失败");
        exit(0);
    }
    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, fpGray);
    fread(fi, sizeof(fileInfo), 1, fpGray);
    //修改头信息
    fi->biBitCount = 8;
    fi->biSizeImage = ((fi->biWidth * 3 + 3) / 4) * 4 * fi->biHeight;
    fi->biClrUsed=256;

    fh->bfOffBits = sizeof(fileHeader) + sizeof(fileInfo) + 256 * sizeof(rgbq);
    fh->bfSize = fh->bfOffBits + fi->biSizeImage;
    fq = (rgbq*)malloc(256 * sizeof(rgbq));
    for (i = 0; i < 256; i++)
    {
        fq[i].rgbBlue = fq[i].rgbGreen = fq[i].rgbRed = i;
        fq[i].rgbReserved=0;
    }
    fread(fq, sizeof(rgbq), 256, fpGray);
    //将头信息写入
    fwrite(fh, sizeof(fileHeader), 1, fpGrayAverage);
    fwrite(fi, sizeof(fileInfo), 1, fpGrayAverage);
    fwrite(fq, sizeof(rgbq), 256, fpGrayAverage);
    int count[256] = { 0 };//各灰阶的数量
    float probability[256] = { 0 }/*各灰阶的概率*/, sumprob[256] = { 0 };//概率求和
    for (i = 0; i < fi->biHeight; i++)
    {
        for (j = 0; j <fi->biWidth; j++)
        {
            fread(&ImgData2[i][j], 1, 1, fpGray);
        }
    }
    for (i = 0; i < fi->biHeight; i++)
    {
        for (j = 0; j < fi->biWidth; j++) 
        {
            count[ImgData2[i][j]]++;
            
        }
    }
    if (i == fi->biHeight)
    {
        for (int x = 0; x < 256; x++)
            probability[x] = (float)count[x] / (float)(fi->biWidth * fi->biHeight);
        for (int x = 0; x < 256; x++)
        {
            if (x == 0)
                sumprob[x] = probability[x];
            else
                sumprob[x] = sumprob[x - 1] + probability[x];
        }
    }

    for (i = 0; i < fi->biHeight; i++)
    {
        for (j = 0; j < fi->biWidth; j++)
        {
            ImgData3[j] = (int)floor((double)(255 * sumprob[ImgData2[i][j]]+0.5));//直方图均衡

        }
        //将灰度图信息写入
        fwrite(ImgData3, j, 1, fpGrayAverage);

    }
    free(fh);
    free(fi);
    free(fq);
    fclose(fpGray);
    fclose(fpGrayAverage);
    printf("success\n");
    return 0;
}

运行示例：
输入：

输出：