c语言读BMP图像的问题
一个读BMP图像的小程序
//ReadBitMap
//
#include <string.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>
#include <malloc.h>
#define WIDTHBYTES(bits) (((bits)+31)/32*4)
typedef unsigned char BYTE;
typedef unsigned short WORD;
typedef unsigned long DWORD;
typedef long LONG;
//位图文件头信息结构定义
//其中不包含文件类型信息（由于结构体的内存结构决定，要是加了的话将不能正确读取文件信息）
typedef struct tagBITMAPFILEHEADER {
DWORD bfSize; //文件大小
WORD bfReserved1; //保留字，不考虑
WORD bfReserved2; //保留字，同上
DWORD bfOffBits; //实际位图数据的偏移字节数，即前三个部分长度之和
} BITMAPFILEHEADER;
//信息头BITMAPINFOHEADER，也是一个结构，其定义如下：
typedef struct tagBITMAPINFOHEADER{
//public:
DWORD biSize; //指定此结构体的长度，为40
LONG biWidth; //位图宽
LONG biHeight; //位图高
WORD biPlanes; //平面数，为1
WORD biBitCount; //采用颜色位数，可以是1，2，4，8，16，24，新的可以是32
DWORD biCompression; //压缩方式，可以是0，1，2，其中0表示不压缩
DWORD biSizeImage; //实际位图数据占用的字节数
LONG biXPelsPerMeter; //X方向分辨率
LONG biYPelsPerMeter; //Y方向分辨率
DWORD biClrUsed; //使用的颜色数，如果为0，则表示默认值(2^颜色位数)
DWORD biClrImportant; //重要颜色数，如果为0，则表示所有颜色都是重要的
} BITMAPINFOHEADER;
//调色板Palette，当然，这里是对那些需要调色板的位图文件而言的。24位和32位是不需要调色板的。
//（似乎是调色板结构体个数等于使用的颜色数。）
typedef struct tagRGBQUAD {
//public:
BYTE rgbBlue; //该颜色的蓝色分量
BYTE rgbGreen; //该颜色的绿色分量
BYTE rgbRed; //该颜色的红色分量
BYTE rgbReserved; //保留值
} RGBQUAD;
void showBmpHead(BITMAPFILEHEADER* pBmpHead)
{
printf("位图文件头:\n");
printf("文件大小:%d\n",pBmpHead->bfSize);
printf("保留字:%d\n",pBmpHead->bfReserved1);
printf("保留字:%d\n",pBmpHead->bfReserved2);
printf("实际位图数据的偏移字节数:%d\n",pBmpHead->bfOffBits);
}
void showBmpInforHead(tagBITMAPINFOHEADER* pBmpInforHead)
{
printf("位图信息头:\n");
printf("结构体的长度:%d\n",pBmpInforHead->biSize);
printf("位图宽:%d\n",pBmpInforHead->biWidth);
printf("位图高:%d\n",pBmpInforHead->biHeight);
printf("biPlanes平面数:%d\n",pBmpInforHead->biPlanes);
printf("biBitCount采用颜色位数:%d\n",pBmpInforHead->biBitCount);
printf("压缩方式:%d\n",pBmpInforHead->biCompression);
printf("biSizeImage实际位图数据占用的字节数:%d\n",pBmpInforHead->biSizeImage);
printf("X方向分辨率:%d\n",pBmpInforHead->biXPelsPerMeter);
printf("Y方向分辨率:%d\n",pBmpInforHead->biYPelsPerMeter);
printf("使用的颜色数:%d\n",pBmpInforHead->biClrUsed);
printf("重要颜色数:%d\n",pBmpInforHead->biClrImportant);
}
void showRgbQuan(tagRGBQUAD* pRGB)
{
printf("(%-3d,%-3d,%-3d) ",pRGB->rgbRed,pRGB->rgbGreen,pRGB->rgbBlue);
}
void main()
{
BITMAPFILEHEADER bitHead;
BITMAPINFOHEADER bitInfoHead;
FILE* pfile;
char strFile[50];
printf("please input the .bmp file name:\n");
scanf("%s",strFile);
pfile = fopen(strFile,"rb");//打开文件
if(pfile!=NULL)
{
printf("file bkwood.bmp open success.\n");
//读取位图文件头信息
WORD fileType;
fread(&fileType,1,sizeof(WORD),pfile);
if(fileType != 0x4d42)
{
printf("file is not .bmp file!");
return;
}
//fseek(pfile,2,SEEK_CUR); // "BM"
fread(&bitHead,1,sizeof(tagBITMAPFILEHEADER),pfile);
showBmpHead(&bitHead);
printf("\n\n");
//读取位图信息头信息
fread(&bitInfoHead,1,sizeof(BITMAPINFOHEADER),pfile);
showBmpInforHead(&bitInfoHead);
printf("\n");
}
else
{
printf("file open fail!\n");
return;
}
tagRGBQUAD *pRgb ;
if(bitInfoHead.biBitCount < 24)//有调色板
{
//读取调色盘结信息
long nPlantNum = long(pow(2,double(bitInfoHead.biBitCount))); // Mix color Plant Number;
pRgb=(tagRGBQUAD *)malloc(nPlantNum*sizeof(tagRGBQUAD));
memset(pRgb,0,nPlantNum*sizeof(tagRGBQUAD));
int num = fread(pRgb,4,nPlantNum,pfile);
printf("Color Plate Number: %d\n",nPlantNum);
printf("颜色板信息:\n");
for (int i =0; i <nPlantNum;i++)
{
if (i%5==0)
{
printf("\n");
}
showRgbQuan(&pRgb[i]);
}
printf("\n");
}
int width = bitInfoHead.biWidth;
int height = bitInfoHead.biHeight;
//分配内存空间把源图存入内存
int l_width = WIDTHBYTES(width* bitInfoHead.biBitCount);//计算位图的实际宽度并确保它为32的倍数
BYTE *pColorData=(BYTE *)malloc(height*l_width);
memset(pColorData,0,height*l_width);
long nData = height*l_width;
//把位图数据信息读到数组里
fread(pColorData,1,nData,pfile);
//将位图数据转化为RGB数据
tagRGBQUAD* dataOfBmp;
dataOfBmp = (tagRGBQUAD *)malloc(width*height*sizeof(tagRGBQUAD));//用于保存各像素对应的RGB数据
memset(dataOfBmp,0,width*height*sizeof(tagRGBQUAD));
if(bitInfoHead.biBitCount <24)//有调色板，即位图为非真彩色
{
int k;
int index = 0;
if (bitInfoHead.biBitCount == 1)
{
for(int i=0;i <height;i++)
for(int j=0;j <width;j++)
{
BYTE mixIndex= 0;
k = i*l_width + j/8;//k:取得该像素颜色数据在实际数据数组中的序号
//j:提取当前像素的颜色的具体值
mixIndex = pColorData[k];
switch(j%8)
{
case 0:
mixIndex = mixIndex < <7;
mixIndex = mixIndex>>7;
break;
case 1:
mixIndex = mixIndex < <6;
mixIndex = mixIndex>>7;
break;
case 2:
mixIndex = mixIndex < <5;
mixIndex = mixIndex>>7;
break;
case 3:
mixIndex = mixIndex < <4;
mixIndex = mixIndex>>7;
break;
case 4:
mixIndex = mixIndex < <3;
mixIndex = mixIndex>>7;
break;
case 5:
mixIndex = mixIndex < <2;
mixIndex = mixIndex>>7;
break;
case 6:
mixIndex = mixIndex < <1;
mixIndex = mixIndex>>7;
break;
case 7:
mixIndex = mixIndex>>7;
break;
}
//将像素数据保存到数组中对应的位置
dataOfBmp[index].rgbRed = pRgb[mixIndex].rgbRed;
dataOfBmp[index].rgbGreen = pRgb[mixIndex].rgbGreen;
dataOfBmp[index].rgbBlue = pRgb[mixIndex].rgbBlue;
dataOfBmp[index].rgbReserved = pRgb[mixIndex].rgbReserved;
index++;
}
}
if(bitInfoHead.biBitCount==2)
{
for(int i=0;i <height;i++)
for(int j=0;j <width;j++)
{
BYTE mixIndex= 0;
k = i*l_width + j/4;//k:取得该像素颜色数据在实际数据数组中的序号
//j:提取当前像素的颜色的具体值
mixIndex = pColorData[k];
switch(j%4)
{
case 0:
mixIndex = mixIndex < <6;
mixIndex = mixIndex>>6;
break;
case 1:
mixIndex = mixIndex < <4;
mixIndex = mixIndex>>6;
break;
case 2:
mixIndex = mixIndex < <2;
mixIndex = mixIndex>>6;
break;
case 3:
mixIndex = mixIndex>>6;
break;
}
//将像素数据保存到数组中对应的位置
dataOfBmp[index].rgbRed = pRgb[mixIndex].rgbRed;
dataOfBmp[index].rgbGreen = pRgb[mixIndex].rgbGreen;
dataOfBmp[index].rgbBlue = pRgb[mixIndex].rgbBlue;
dataOfBmp[index].rgbReserved = pRgb[mixIndex].rgbReserved;
index++;
}
}
if(bitInfoHead.biBitCount == 4)
{
for(int i=0;i <height;i++)
for(int j=0;j <width;j++)
{
BYTE mixIndex= 0;
k = i*l_width + j/2;
mixIndex = pColorData[k];
if(j%2==0)
{//低
mixIndex = mixIndex < <4;
mixIndex = mixIndex>>4;
}
else
{//高
mixIndex = mixIndex>>4;
}
dataOfBmp[index].rgbRed = pRgb[mixIndex].rgbRed;
dataOfBmp[index].rgbGreen = pRgb[mixIndex].rgbGreen;
dataOfBmp[index].rgbBlue = pRgb[mixIndex].rgbBlue;
dataOfBmp[index].rgbReserved = pRgb[mixIndex].rgbReserved;
index++;
}
}
if(bitInfoHead.biBitCount == 8)
{
for(int i=0;i <height;i++)
for(int j=0;j <width;j++)
{
BYTE mixIndex= 0;
k = i*l_width + j;
mixIndex = pColorData[k];
dataOfBmp[index].rgbRed = pRgb[mixIndex].rgbRed;
dataOfBmp[index].rgbGreen = pRgb[mixIndex].rgbGreen;
dataOfBmp[index].rgbBlue = pRgb[mixIndex].rgbBlue;
dataOfBmp[index].rgbReserved = pRgb[mixIndex].rgbReserved;
index++;
}
}
if(bitInfoHead.biBitCount == 16)
{
for(int i=0;i <height;i++)
for(int j=0;j <width;j++)
{
WORD mixIndex= 0;
k = i*l_width + j*2;
WORD shortTemp;
shortTemp = pColorData[k+1];
shortTemp = shortTemp < <8;
mixIndex = pColorData[k] + shortTemp;
dataOfBmp[index].rgbRed = pRgb[mixIndex].rgbRed;
dataOfBmp[index].rgbGreen = pRgb[mixIndex].rgbGreen;
dataOfBmp[index].rgbBlue = pRgb[mixIndex].rgbBlue;
dataOfBmp[index].rgbReserved = pRgb[mixIndex].rgbReserved;
index++;
}
}
}
else//位图为24位真彩色
{
int k;
int index = 0;
for(int i=0;i <height;i++)
for(int j=0;j <width;j++)
{
k = i*l_width + j*3;
dataOfBmp[index].rgbRed = pColorData[k+2];
dataOfBmp[index].rgbGreen = pColorData[k+1];
dataOfBmp[index].rgbBlue = pColorData[k];
index++;
}
}
printf("像素数据信息:\n");
for (int i=0; i <width*height; i++)
{
if (i%5==0)
{
printf("\n");
}
showRgbQuan(&dataOfBmp[i]);
}
fclose(pfile);
if (bitInfoHead.biBitCount <24)
{
free(pRgb);
}
free(dataOfBmp);
free(pColorData);
printf("\n");
}
2位的位图第一次听说。if(bitInfoHead.biBitCount<24)//这句错的，16位的也没有调色板。移位那个是用来取得一个BYTE里的某两位bit位的；比如：BYTE byte=11001010要取得byte左边两位的值，则可以byte>>6得到11；要取得byte右边两位的值，则可以先byte<<6把左边六位清零，再byte>>6得到10；另外，移位那里顺序通通是错的。这里改其中一个：f (bitInfoHead.biBitCount == 1){for(int i=0;i<height;i++)for(int j=0;j<width;j++){BYTE mixIndex= 0;k = i*l_width + j/8;//k:取得该像素颜色数据在实际数据数组中的序号//j:提取当前像素的颜色的具体值mixIndex = pColorData[k];switch(j%8){case 7:mixIndex = mixIndex<<7;mixIndex = mixIndex>>7;break;case 6:mixIndex = mixIndex<<6;mixIndex = mixIndex>>7;break;case 5:mixIndex = mixIndex<<5;mixIndex = mixIndex>>7;break;case 4:mixIndex = mixIndex<<4;mixIndex = mixIndex>>7;break;case 3:mixIndex = mixIndex<<3;mixIndex = mixIndex>>7;break;case 2:mixIndex = mixIndex<<2;mixIndex = mixIndex>>7;break;case 1:mixIndex = mixIndex<<1;mixIndex = mixIndex>>7;break;case 0:mixIndex = mixIndex>>7;break;}