bmp图片格式及读取

C++读取bmp图片的例子

  1 #include  
  2 #include  
  3 #include  
  4 #include <malloc.h> 
  5 
  6 #define WIDTHBYTES(x) ((x+31)/32*4)
  7 #define my(x)  ( ( (x + 31) & ~31) / 8)
  8 
  9 BITMAPFILEHEADER bf; //BMP文件头结构体
 10 BITMAPINFOHEADER bi; //BMP信息头结构体
 11 
 12 int i,j;
 13 RGBQUAD *ipRGB;        //颜色表 
 14 DWORD NumColors;    //颜色表数目
 15 unsigned char ** Imgdata;
 16 
 17 void read(char*);
 18 void display();
 19 void org(char*);
 20 void gray(char*);
 21 
 22 void test()
 23 {
 24     DWORD LineByte;
 25     DWORD ImgSize; 
 26     LineByte=(DWORD)my(bi.biWidth*bi.biBitCount); //计算位图的实际宽度并确保它为32的倍数
 27     ImgSize=(DWORD)LineByte*bi.biHeight; 
 28     printf("LineByte            is %d. \n", LineByte);             
 29     printf("ImgSize             is %d. \n", ImgSize);
 30 }
 31     
 32 int main() 
 33 {         
 34      char *filename;
 35      filename="U616.bmp";
 36      read(filename);
 37      display(); 
 38      test();
 39      org("123.bmp"); 
 40      free(Imgdata); 
 41    //  printf("<2>");
 42    //  display();
 43      free(ipRGB); 
 44      system("pause");
 45      return 0; 
 46 } 
 47 
 48 void read(char* filename)
 49 {
 50     FILE* fp;
 51     fp=fopen(filename,"rb"); 
 52     if(fp == NULL)
 53     {
 54         printf("Open file error!");
 55         exit(0);
 56     }
 57 
 58     //读取信息头、文件头
 59     fread(&bf,sizeof(BITMAPFILEHEADER),1,fp); 
 60     fread(&bi,sizeof(BITMAPINFOHEADER),1,fp); 
 61     
 62     if (bi.biClrUsed != 0 ) 
 63         NumColors=(DWORD)bi.biClrUsed; 
 64     else 
 65          switch (bi.biBitCount) 
 66           {    
 67                case 1:            NumColors=2;     break; 
 68              case 4:            NumColors=16;    break; 
 69                case 8:            NumColors=256;   break; 
 70             case 24:           NumColors=0;     break; 
 71         } 
 72                 
 73      //分配调色板内存
 74      ipRGB=(RGBQUAD *)malloc(NumColors*sizeof(RGBQUAD)); 
 75      fread(ipRGB,sizeof(RGBQUAD),NumColors,fp); 
 76 
 77      Imgdata=new unsigned char*[bi.biHeight]; //声明一个指针数组
 78      if(bi.biBitCount==24)
 79      {
 80          for ( i=(bi.biHeight)-1;i>=0;i--) 
 81                 Imgdata[i]=new unsigned char[bi.biWidth*3]; //每个数组元素也是一个指针数组
 82 
 83          for ( i=(bi.biHeight)-1;i>=0;i--) 
 84                 for(j=0;j3;j++) 
 85                   fread(&Imgdata[i][j],1,1,fp);//每次只读取一个1字节，存入数组
 86       } 
 87      else 
 88      {
 89          for ( i=(bi.biHeight)-1;i>=0;i--) 
 90              Imgdata[i]=new unsigned char[bi.biWidth]; 
 91 
 92          for ( i=(bi.biHeight)-1;i>=0;i--) 
 93              for(j=0;j) 
 94                    fread(&Imgdata[i][j],1,1,fp);
 95      }
 96 
 97      fclose(fp);
 98 }
 99  
100 void org(char *filename)
101 {
102      FILE* fp;
103      fp=fopen(filename,"wb"); 
104      fwrite(&bf,sizeof(BITMAPFILEHEADER),1,fp); //写文件头 
105      fwrite(&bi,sizeof(BITMAPINFOHEADER),1,fp); //写信息头 
106      fwrite(ipRGB,sizeof(RGBQUAD),NumColors,fp);//写颜色头 
107 
108      if(bi.biBitCount==24)
109          for (i=(bi.biHeight)-1 ;i>=0;i--) 
110               for (j=0 ;j3);j++) 
111                   fwrite(&Imgdata[i][j],1,1,fp);
112      else
113          for (i=(bi.biHeight)-1 ;i>=0;i--) 
114              for (j=0 ;j)
115                     fwrite(&Imgdata[i][j],1,1,fp);
116      fclose(fp);
117 }
118 
119 void gray(char *filename)
120 {
121      FILE* fp;
122      fp=fopen(filename,"wb"); 
123     /* 
124      bf.bfOffBits=(DWORD)1078;
125      bi.biSizeImage=(DWORD)(bi.biWidth*bi.biHeight);
126      bf.bfSize=bi.biSizeImage+bf.bfOffBits;
127      bi.biBitCount=(WORD)8;
128      bi.biClrUsed=(DWORD)256;
129      bi.biClrImportant=(DWORD)256;
130      bi.biXPelsPerMeter=(LONG)0;
131      bi.biYPelsPerMeter=(LONG)0;
132      NumColors=(DWORD)bi.biClrUsed;
133      ipRGB=(RGBQUAD *)malloc(NumColors*sizeof(RGBQUAD));
134      */
135      fwrite(&bf,sizeof(BITMAPFILEHEADER),1,fp); //写文件头 
136      fwrite(&bi,sizeof(BITMAPINFOHEADER),1,fp); //写信息头 
137      fwrite(ipRGB,sizeof(RGBQUAD),NumColors,fp);//写颜色头 
138 
139      char temp;
140      for (i=(bi.biHeight)-1 ;i>=0;i--) 
141          for (j=0 ;j3;j++) 
142              if(j%3==0)
143              {
144                        temp=(Imgdata[i][j]*76+Imgdata[i][j+1]*151+Imgdata[i][j+2]*28)>>8;
145                        fwrite(&temp,1,1,fp);
146              }
147              else
148              {
149                        fwrite(&temp,1,1,fp);
150              }
151      fclose(fp);
152  }
153  
154 void display()
155 {
156     printf("tagBITMAPFILEHEADER info is: %d\n",sizeof(BITMAPFILEHEADER));
157     printf("bfType              is %d.\n", bf.bfType);
158     printf("bfSize              is %d.\n", bf.bfSize);
159     printf("bfReserved1         is %d.\n", bf.bfReserved1);
160     printf("bfReserved2         is %d.\n", bf.bfReserved2);
161     printf("bfOffBits           is %d.\n", bf.bfOffBits);
162 
163     printf("\ntagBITMAPINFOHEADER info is: %d\n",sizeof(BITMAPINFOHEADER));
164     printf("biSize              is %d. \n", bi.biSize);
165     printf("biWidth             is %ld.\n", bi.biWidth);
166     printf("biHeight            is %ld.\n", bi.biHeight);
167     printf("biPlanes            is %d. \n", bi.biPlanes);
168     printf("biBitCount          is %d. \n", bi.biBitCount);       //每像素所需位数 
169     printf("biCompression       is %d. \n", bi.biCompression);
170     printf("biSizeImage         is %d. \n", bi.biSizeImage);
171     printf("biXPelsPerMerer     is %ld.\n", bi.biXPelsPerMeter);  //每米像素数 
172     printf("biYPelsPerMerer     is %ld.\n", bi.biYPelsPerMeter);
173     printf("biClrUsed           is %d. \n", bi.biClrUsed);
174     printf("biClrImportant      is %d. \n", bi.biClrImportant);
175     printf("\nNum of colors     is %d. \n", NumColors);
176  }

 

转载于:https://www.cnblogs.com/luangeng/p/5831145.html