BMP图像差分/比较

 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>

 int main(int argc, char *argv[])
 {
     int row, col;
     int width, height, widthbyte, bitcount, imagesize, bytecount;
     const char *magenta = NULL;
     const char *magendiff = NULL;
     unsigned char header[] =
     {
         0x42, 0x4D, 0xAA, 0xAA, 0xAA, 0xAA, 0x00, 0x00, //  2 AA->FileSize
         0x00, 0x00, 0xBB, 0xBB, 0xBB, 0xBB, 0x28, 0x00, // 10 BB->OffBits
         0x00, 0x00, 0xCC, 0xCC, 0xCC, 0xCC, 0xDD, 0xDD, // 18 CC->Width
         0xDD, 0xDD, 0x01, 0x00, 0xEE, 0xEE, 0x00, 0x00, // 22 DD->Height
         0x00, 0x00, 0xFF, 0xFF, 0xFF, 0xFF, 0x00, 0x00, // 28 EE->BitCount
         0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // 34 FF->ImageSize
         0x00, 0x00, 0x00, 0x00, 0x00, 0x00
     };

     FILE *fpA = NULL;
     FILE *fpB = NULL;
     FILE *fpC = NULL;
     const char *filenameA = "A.bmp";
     const char *filenameB = "B.bmp";
     const char *filenameC = "C.bmp";
     unsigned char *rowbufA = NULL;
     unsigned char *rowbufB = NULL;

     const char * errmsg = NULL;

     switch(argc)
     {
     case :
         break;
     case :
         break;
     case :
         filenameA = argv[];
         filenameB = argv[];
         break;
     case :
         filenameA = argv[];
         filenameB = argv[];
         filenameC = argv[];
         break;
     }

     do
     {
         fpA = fopen(filenameA, "rb");
         if(fpA == NULL) { errmsg = "A.bmp open failed"; break; };

         fpB = fopen(filenameB, "rb");
         if(fpB == NULL) { errmsg = "B.bmp open failed"; break; };

         // read file A.bmp
         fread(header, sizeof(header), 1L, fpA);
         width = *((int *)(header + ));
         height = *((int *)(header + ));
         bitcount = *((short *)(header + ));
         imagesize = *((int *)(header + ));
         widthbyte = (width * bitcount + ) /  * ;
         bytecount = bitcount / ;
         switch(bitcount)
         {
         case :
             magenta = "\x1F\x7C";
             magendiff = "\x1F\x7C";
             break;
         case :
         case :
             magenta = "\x00\x00\x00\x00";
             magendiff = "\x00\x00\xFF\xFF";
             break;
         default:
             errmsg = "A.bitcount != 16 or 24 or 32";
             break;
         }
         if(errmsg) break;

         // check file B.bmp
         fread(header, sizeof(header), 1L, fpB);
         if(width != *((int *)(header + ))) { errmsg = "A.width != B.width"; break; }
         if(height != *((int *)(header + ))) { errmsg = "A.height != B.height"; break; }
         if(bitcount != *((short *)(header + ))) { errmsg = "A.bitcount != B.bitcount"; break; }
         if(imagesize != *((int *)(header + ))) { errmsg = "A.imagesize != B.imagesize"; break; }

         rowbufA = (unsigned char *)malloc(widthbyte);
         if(rowbufA == NULL) { errmsg = "rowbufA malloc failed"; break; }

         rowbufB = (unsigned char *)malloc(widthbyte);
         if(rowbufB == NULL) { errmsg = "rowbufB malloc failed"; break; }

         fpC = fopen(filenameC, "wb");
         if(fpC == NULL) { errmsg = "C.bmp open failed"; break; };

         // wirte file C.bmp
         fwrite(header, sizeof(header), 1L, fpC);
         for(row = ; row < height; row++)
         {
             fread(rowbufA, widthbyte, , fpA);
             fread(rowbufB, widthbyte, , fpB);

             for(col = ; col < width; col++)
             {
                 if(memcmp(rowbufA + bytecount * col, rowbufB + bytecount * col, bytecount) == )
                 {
                     memcpy(rowbufB + bytecount * col, magenta, bytecount);
                 }
                 else
                 {
                     memcpy(rowbufB + bytecount * col, magendiff, bytecount);
                 }
             }

             fwrite(rowbufB, widthbyte, , fpC);
         }

     } while();

     if(fpA) fclose(fpA);
     if(fpB) fclose(fpB);
     if(fpC) fclose(fpC);
     if(rowbufA) free(rowbufA);
     if(rowbufB) free(rowbufB);

     if(errmsg)
     {
         printf("%s\n", errmsg);
         system("PAUSE");
     }

     return ;
 }