C语言将BMP格式图片转化为灰度

矫情吗；* 2022-06-12 01:20 294阅读 0赞

# 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;
    }

![原始图片][SouthEast]  
![转换后的图片][SouthEast 1]

[SouthEast]: /images/20220612/462819a5993a410c964f99e633a3e46d.png
[SouthEast 1]: /images/20220612/1f6268c610e44e6b81dc21e947900115.png