无法正确读取.bmp头文件

我试图接受一个.bmp文件并最终逐个编辑像素，但我想出了INFOHEADER结构中返回给我的宽度和高度的问题。 返回的宽度是13107200，高度是65536.但是，每当我运行程序时，总共只计算了60003个像素。 我不知道为什么会这样。 任何帮助将不胜感激。

#include  #include  int main( int argc, char *argv[] ){ //define structures typedef struct { unsigned short int Type; /* Magic identifier */ unsigned int Size; /* File size in bytes */ unsigned short int Reserved1, Reserved2; unsigned int Offset; /* Offset to data (in B)*/ }HEADER; /* -- 14 Bytes -- */ typedef struct { unsigned int Size; /* Header size in bytes */ int Width, Height; /* Width / Height of image */ unsigned short int Planes; /* Number of colour planes */ unsigned short int Bits; /* Bits per pixel */ unsigned int Compression; /* Compression type */ unsigned int ImageSize; /* Image size in bytes */ int xResolution, yResolution;/* Pixels per meter */ unsigned int Colors; /* Number of colors */ unsigned int ImportantColors;/* Important colors */ }INFOHEADER; /* -- 40 Bytes -- */ typedef struct { unsigned char Red, Green, Blue; }PIXEL; //make instance of all three structures HEADER data; INFOHEADER data2; PIXEL pixel; //declare file read pointer FILE *file; //declare fileout read pointer //FILE *fileout; //declare file printed file pointer // open file 1 of argument counter and return 0 apon error if( !(file = fopen( "CU.bmp","rb")))return 0; //read HEADER data into data fread(&data,sizeof(HEADER),1,file); //read IB+NFOHEADER data into data2 fread(&data2,sizeof(INFOHEADER),1,file); //Print PIXEL data //Allocate space for pixelarray PIXEL **pixelarray; int r=0,c=0,rows=data2.Height,collumns=data2.Width; pixelarray= malloc(rows*sizeof(PIXEL *)); for(r=0; r<rows; r++){ pixelarray[r]=malloc(collumns*sizeof(PIXEL)); } //fill pixel array with pixel structs r=0;c=0; int pixelnum=1; while( fread(&pixel,sizeof(PIXEL),1,file) ){ if(c == collumns){ c=0; r++; } pixelarray[r][c] = pixel; printf("\nPixel %10d: %02X%02X%02X",pixelnum,pixelarray[r][c].Red,pixelarray[r][c].Blue,pixelarray[r][c].Green); fflush(stdout); c++;pixelnum++; } free(pixelarray); fclose(file); //close the files prior to exiting 

Answer 1

我想你的问题是structure alignment 。 你可以在这里和这里参考它。 要消除它，请使用#pragma指令。 所以你的结构声明将是这样的：

 #pragma pack(push) // push current alignment to stack #pragma pack(1) // set alignment to 1 byte boundary typedef struct { unsigned short int Type; /* Magic identifier */ unsigned int Size; /* File size in bytes */ unsigned short int Reserved1; unsigned short int Reserved2; unsigned int Offset; /* Offset to data (in B)*/ }HEADER; /* -- 14 Bytes -- */ typedef struct { unsigned int Size; /* Header size in bytes */ int Width; int Height; /* Width / Height of image */ unsigned short int Planes; /* Number of colour planes */ unsigned short int Bits; /* Bits per pixel */ unsigned int Compression; /* Compression type */ unsigned int ImageSize; /* Image size in bytes */ int xResolution; int yResolution;/* Pixels per meter */ unsigned int Colors; /* Number of colors */ unsigned int ImportantColors;/* Important colors */ }INFOHEADER; /* -- 40 Bytes -- */ typedef struct { unsigned char Red; unsigned char Green; unsigned char Blue; }PIXEL; #pragma pack(pop) // restore original alignment from stack 

这可以正确读取BMP图像的宽度和高度。 在读取图像数据时，请直接进行：

 for( r=0; r 

Answer 2

对于宽度和高度，必须使用16位变量（无符号短）而不是int。 根据维基百科 ，宽度/高度是16位。

Answer 3

在hex编辑器中打开bmp文件，查看info标题中的值。 然后调试代码并检查您在infoheader中读取的值。