C語言實現BMP格式圖片轉化為灰度

#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數據在文件中的偏移量
}fileHeader;
#pragma pack()
/*
位圖數據信息結構
*/
#pragma pack(1)
typedef struct tagBITMAPINFOHEADER
{
    unsigned long biSize;//該結構的大小
    long biWidth;//文件寬度
    long biHeight;//文件高度
    unsigned short biPlanes;//平面數
    unsigned short biBitCount;//顏色位數
    unsigned long biCompression;//壓縮類型
    unsigned long biSizeImage;//DIB數據區大小
    long biXPixPerMeter;
    long biYPixPerMeter;
    unsigned long biClrUsed;//多少顏色索引表
    unsigned long biClrImporant;//多少重要顏色
}fileInfo;
#pragma pack()
/*
調色板結構
*/
#pragma pack(1)
typedef struct tagRGBQUAD
{
    unsigned char rgbBlue; //藍色分量亮度
    unsigned char rgbGreen;//綠色分量亮度
    unsigned char rgbRed;//紅色分量亮度
    unsigned char rgbReserved;
}rgbq;
#pragma pack()
 
int main()
{
    FILE *fp1 = fopen("C:\\Users\\Administrator\\Desktop\\data\\bmp\\image.bmp", "rb+");
    if (fp1 == NULL)
    {
        printf("打開文件fp1失敗");
        exit(0);
    }
 
    FILE *fp2 = fopen("C:\\Users\\Administrator\\Desktop\\data\\bmp\\imageGray.bmp", "wb");
    if (fp1 == NULL)
    {
        printf("打開文件fp2失敗");
        exit(0);
    }
 
    fileHeader * fh;
    fileInfo * fi;
    fh = (fileHeader *)malloc(sizeof(fileHeader));
    fi = (fileInfo *)malloc(sizeof(fileInfo));
 
    //讀取位圖頭結構和信息頭
    fread(fh, sizeof(fileHeader), 1, fp1);
    fread(fi, sizeof(fileInfo), 1, fp1);
 
    printf("\\\\\\\\\\\\\\\\\\\\原始圖片信息\\\\\\\\\\\\\\\\\\\\\\\\\\\n");
    printf("bmp文件頭：\n");
    printf("bfSize:%d\n", fh->bfSize);
    printf("bfOffBits:%d\n", fh->bfOffBits);
    printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n");
    printf("bmp信息頭\n");
    printf("結構體長度：%d \n", fi->biSize);
    printf("位圖寬度：%d \n", fi->biWidth);
    printf("位圖高度：%d \n", fi->biHeight);
    printf("位圖平面數：%d \n", fi->biPlanes);
    printf("顏色位數：%d \n", fi->biBitCount);
    printf("壓縮方式：%d \n", fi->biCompression);
    printf("實際位圖數據占用的字節數：%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("使用的顏色數：%d \n", fi->biClrUsed);
    printf("重要顏色數：%d \n", fi->biClrImporant);
    printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n");
 
    //修改信息頭
    fi->biBitCount = 8;
    //fi->biSizeImage = ((fi->biWidth * 3 + 3) / 4) * 4 * fi->biHeight;
    fi->biSizeImage = fi->biHeight*fi->biWidth;
    //修改文件頭
    fh->bfOffBits = sizeof(fileHeader) + sizeof(fileInfo) + 256 * sizeof(rgbq);
    fh->bfSize = fh->bfOffBits + fi->biSizeImage;
 
    printf("\\\\\\\\\\\\\\\\\\\\修改後的圖片信息\\\\\\\\\\\\\\\\\\\\\\\\\\\n");
    printf("bmp文件頭：\n");
    printf("bfSize:%d\n", fh->bfSize);
    printf("bfOffBits:%d\n", fh->bfOffBits);
    printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n");
    printf("bmp信息頭\n");
    printf("結構體長度：%d \n", fi->biSize);
    printf("位圖寬度：%d \n", fi->biWidth);
    printf("位圖高度：%d \n", fi->biHeight);
    printf("位圖平面數：%d \n", fi->biPlanes);
    printf("顏色位數：%d \n", fi->biBitCount);
    printf("壓縮方式：%d \n", fi->biCompression);
    printf("實際位圖數據占用的字節數：%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("使用的顏色數：%d \n", fi->biClrUsed);
    printf("重要顏色數：%d \n", fi->biClrImporant);
    printf("\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\n");
 
    //創建調色板
    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;
    }
    //寫入文件頭、信息頭、調色板
    fwrite(fh, sizeof(fileHeader), 1, fp2);
    fwrite(fi, sizeof(fileInfo), 1, fp2);
    fwrite(fq, sizeof(rgbq), 256, fp2);
 
    //將位圖信息轉為灰度
    //存儲bmp一行的像素點
    //unsigned char ImgData[900][3];
    unsigned char ImgData[3000][3];
    //將灰度圖像存到一維數組中
    //unsigned char grayData2[900];
    unsigned char ImgData2[3000];
    /*
    //錯誤的算法
    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);
        }
        //將灰度圖信息寫入
        fwrite(ImgData2, j, 1, fp2);
    }
    */
    /*
    //正確的算法(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);
        }
        //將灰度圖信息寫入
        fwrite(ImgData2, j, 1, fp2);
    }
    */
    //正確算法（2）
    unsigned char * * bmp_data;
    bmp_data = new unsigned char*[fi->biHeight]; //聲明一個指針數組
    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]; //每個數組元素也是一個指針數組
    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);//每次隻讀取一個字節，存入數組
 
    for (i = 0; i<fi->biHeight; i++)//將24位真彩色轉換成灰度圖
        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;
}