24位转8位

BOOL BMP24to8(char *szSourceFile,char *szTargetFile)

{

HANDLE hSourceFile=INVALID_HANDLE_VALUE,hTargetFile=INVALID_HANDLE_VALUE;
DWORD dwSourceSize=0,dwTargetSize=0;

PBYTE pSource=NULL,pTarget=NULL;

hSourceFile=CreateFile(szSourceFile,GENERIC_READ,FILE_SHARE_READ,NULL,

OPEN_EXISTING,FILE_ATTRIBUTE_NORMAL,NULL);
if(hSourceFile==INVALID_HANDLE_VALUE)

return FALSE;

dwSourceSize=GetFileSize(hSourceFile,NULL);
pSource=(PBYTE)VirtualAlloc(NULL,dwSourceSize,MEM_COMMIT,PAGE_READWRITE);

//分配空间失败或者文件太小（BMP文件不可能小于54个字节）

if(pSource==NULL||dwSourceSize<=54)

{

CloseHandle(hSourceFile);

return FALSE;

}

DWORD dwTemp=0;

ReadFile(hSourceFile,pSource,dwSourceSize,&dwTemp,NULL);

BITMAPFILEHEADER *pSourceFileHeader=(BITMAPFILEHEADER*)pSource;

BITMAPINFOHEADER *pSourceInfoHeader=(BITMAPINFOHEADER*)(pSource+sizeof(BITMAPFILEHEADER));

//不是BMP文件或者不是24位真彩色

if(pSourceFileHeader->bfType!=0x4d42||pSourceInfoHeader->biBitCount!=24)

{

CloseHandle(hSourceFile);

VirtualFree(pSource,NULL,MEM_RELEASE);

return FALSE;

}

CloseHandle(hSourceFile);

LONG nWidth=pSourceInfoHeader->biWidth;

LONG nHeight=pSourceInfoHeader->biHeight;

LONG nSourceWidth=nWidth*3;if(nSourceWidth%4) nSourceWidth=(nSourceWidth/4+1)*4;

LONG nTargetWidth=nWidth;if(nTargetWidth%4) nTargetWidth=(nTargetWidth/4+1)*4;

dwTargetSize=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+sizeof(RGBQUAD)*256+nHeight*nTargetWidth;

pTarget=(PBYTE)VirtualAlloc(NULL,dwTargetSize,MEM_COMMIT,PAGE_READWRITE);

memset(pTarget,0,dwTargetSize);

if(pTarget==NULL)

{

VirtualFree(pTarget,NULL,MEM_RELEASE <a href="http://snovalleylacrosse.com/">Payday Loan</a>);

return FALSE;

}

BITMAPFILEHEADER *pTargetFileHeader=(BITMAPFILEHEADER *)pTarget;

BITMAPINFOHEADER *pTargetInfoHeader =

(BITMAPINFOHEADER *)(pTarget+sizeof(BITMAPFILEHEADER));

pTargetFileHeader->bfType=pSourceFileHeader->bfType;

pTargetFileHeader->bfSize=dwTargetSize;

pTargetFileHeader->bfReserved1=0;

pTargetFileHeader->bfReserved2=0;

pTargetFileHeader->bfOffBits=sizeof(BITMAPFILEHEADER)

+sizeof(BITMAPINFOHEADER)+sizeof(RGBQUAD)*256;

pTargetInfoHeader->biBitCount=8;

pTargetInfoHeader->biClrImportant=0;

pTargetInfoHeader->biClrUsed=256;

pTargetInfoHeader->biCompression=BI_RGB;

pTargetInfoHeader->biHeight=pSourceInfoHeader->biHeight;

pTargetInfoHeader->biPlanes=1;

pTargetInfoHeader->biSize=sizeof(BITMAPINFOHEADER);

pTargetInfoHeader->biSizeImage=nHeight*nTargetWidth;

pTargetInfoHeader->biWidth=pSourceInfoHeader->biWidth;

pTargetInfoHeader->biXPelsPerMeter=pSourceInfoHeader->biXPelsPerMeter;

pTargetInfoHeader->biYPelsPerMeter=pSourceInfoHeader->biYPelsPerMeter;

RGBQUAD *pRgb;

for(int i=0;i<256;i++)//初始化8位灰度图的调色板信息

{

pRgb = (RGBQUAD*)(pTarget+sizeof(BITMAPFILEHEADER)

+ sizeof(BITMAPINFOHEADER)+i*sizeof(RGBQUAD));

pRgb->rgbBlue=i;pRgb->rgbGreen=i;pRgb->rgbRed=i;pRgb->rgbReserved=0;

}

for (int m=0;m<nHeight;m++)//转化真彩色图为灰度图

{

for(int n=0;n<nWidth;n++)

{

pTarget[pTargetFileHeader->bfOffBits+m*nTargetWidth+n] =

pSource[pSourceFileHeader->bfOffBits+m*nSourceWidth+n*3]*0.114

+pSource[pSourceFileHeader->bfOffBits+m*nSourceWidth+n*3+1]*0.587

+pSource[pSourceFileHeader->bfOffBits+m*nSourceWidth+n*3+2]*0.299;

}

}

hTargetFile = CreateFile(szTargetFile,GENERIC_WRITE,FILE_SHARE_WRITE,

NULL,CREATE_ALWAYS,FILE_ATTRIBUTE_NORMAL,NULL);

BOOL stat=WriteFile(hTargetFile,pTarget,dwTargetSize,&dwTemp,NULL);

CloseHandle(hTargetFile);

VirtualFree(pSource,NULL,MEM_RELEASE);

VirtualFree(pTarget,NULL,MEM_RELEASE);

return stat;

}