C语言实现BMP格式图片转化为灰度

本文为大家分享了C语言将BMP格式图片转化为灰度的具体代码，供大家参考，具体内容如下

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;
}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。

原文链接：https://blog.csdn.net/zb774095236/article/details/89378571