如何把BMP位图转换成灰度图？

Question

小弟刚学编程，现在遇到这样一个问题：如何把BMP位图转换成灰度图？
哪位大哥最好能提供源码！谢谢！！！！！！！！！！！！

Answer 1

BOOL ColorToGray(LPCSTR BmpFileName)
{
DWORD              SrcBufSize,DstBufSize,DstLineBytes;
    LPBITMAPINFOHEADER lpImgData;
LPSTR              lpPtr;
HLOCAL             hTempImgData;
LPBITMAPINFOHEADER lpTempImgData;
LPSTR              lpTempPtr;
HDC                hDc;
HFILE              hf;
LONG               x,y;
BITMAPFILEHEADER   DstBf;
BITMAPINFOHEADER   DstBi;
    LOGPALETTE         *pPal;
    HPALETTE           hPrevPalette; 
HLOCAL             hPal;
DWORD    NewNumColors;
WORD    NewBitCount;
float              Y;
DWORD              i;
unsigned char      Red,Green,Blue,Gray; NewNumColors=NumColors;
NewBitCount=bi.biBitCount;
if(NumColors==0) //true color
{
NewNumColors=256;
NewBitCount=8;
} DstLineBytes=(DWORD)WIDTHBYTES(bi.biWidth*NewBitCount);
DstBufSize=(DWORD)(sizeof(BITMAPINFOHEADER)+NewNumColors*sizeof(RGBQUAD)+(DWORD)DstLineBytes*bi.biHeight);
memcpy((char *)&DstBf,(char *)&bf,sizeof(BITMAPFILEHEADER));
memcpy((char *)&DstBi,(char *)&bi,sizeof(BITMAPINFOHEADER));
DstBf.bfSize=DstBufSize+sizeof(BITMAPFILEHEADER);
DstBf.bfOffBits=(DWORD)(NewNumColors*sizeof(RGBQUAD)+sizeof(BITMAPFILEHEADER)
+sizeof(BITMAPINFOHEADER));
DstBi.biClrUsed=0;
DstBi.biBitCount=NewBitCount; SrcBufSize=bf.bfSize-sizeof(BITMAPFILEHEADER); if((hTempImgData=LocalAlloc(LHND,DstBufSize))==NULL)
    {
     MessageBox("Error alloc memory!","Error Message",MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
    }    lpImgData=(LPBITMAPINFOHEADER)GlobalLock(hImgData);    
lpTempImgData=(LPBITMAPINFOHEADER)LocalLock(hTempImgData); //copy image data
memcpy(lpTempImgData,lpImgData,DstBufSize);
//overwrite bitmapinfoheader with the new one
memcpy(lpTempImgData,(char *)&DstBi,sizeof(BITMAPINFOHEADER)); lpPtr=(char *)lpImgData+sizeof(BITMAPINFOHEADER);
lpTempPtr=(char *)lpTempImgData+sizeof(BITMAPINFOHEADER);    hPal=LocalAlloc(LHND,sizeof(LOGPALETTE) + NewNumColors* sizeof(PALETTEENTRY));
    pPal =(LOGPALETTE *)LocalLock(hPal);
    pPal->palNumEntries =(WORD) NewNumColors;
pPal->palVersion    = 0x300; if(NumColors==0) //true color
for (i = 0; i < 256; i++) {
      pPal->palPalEntry[i].peRed=(BYTE)i;
pPal->palPalEntry[i].peGreen=(BYTE)i;
pPal->palPalEntry[i].peBlue=(BYTE)i;
pPal->palPalEntry[i].peFlags=(BYTE)0;
*(lpTempPtr++)=(unsigned char)i;
*(lpTempPtr++)=(unsigned char)i;
*(lpTempPtr++)=(unsigned char)i;
*(lpTempPtr++)=0;
}
else 
for (i = 0; i < NewNumColors; i++) {
Blue=(unsigned char )(*lpPtr++);
Green=(unsigned char )(*lpPtr++);
Red=(unsigned char )(*lpPtr++);
Y=(float)(Red*0.299+Green*0.587+Blue*0.114);
Gray=(BYTE)Y;
lpPtr++;
      pPal->palPalEntry[i].peRed=Gray;
pPal->palPalEntry[i].peGreen=Gray;
pPal->palPalEntry[i].peBlue=Gray;
pPal->palPalEntry[i].peFlags=0;
*(lpTempPtr++)=(unsigned char)Gray;
*(lpTempPtr++)=(unsigned char)Gray;
*(lpTempPtr++)=(unsigned char)Gray;
*(lpTempPtr++)=0;
} if(hPalette!=NULL)                     
        DeleteObject(hPalette);

hPalette=CreatePalette(pPal);
LocalUnlock(hPal);
LocalFree(hPal); hDc=::GetDC(m_hWnd);
if(hPalette){
        hPrevPalette=SelectPalette(hDc,hPalette,FALSE);
RealizePalette(hDc);
}

if(NumColors==0)
for(y=0;y<bi.biHeight;y++){
lpPtr=(char *)lpImgData+(SrcBufSize-LineBytes-y*LineBytes);
lpTempPtr=(char *)lpTempImgData+(DstBufSize-DstLineBytes-y*DstLineBytes);
for(x=0;x<bi.biWidth;x++){
Blue=(unsigned char )(*lpPtr++);
Green=(unsigned char )(*lpPtr++);
Red=(unsigned char )(*lpPtr++);
Y=(float)(Red*0.299+Green*0.587+Blue*0.114);
Gray=(BYTE)Y;
*(lpTempPtr++)=(unsigned char)Gray;
}
}    if(hBitmap!=NULL)
    DeleteObject(hBitmap);

hBitmap=CreateDIBitmap(hDc, (LPBITMAPINFOHEADER)lpTempImgData, (LONG)CBM_INIT,
(LPSTR)lpTempImgData+sizeof(BITMAPINFOHEADER) +NewNumColors*sizeof(RGBQUAD),
    (LPBITMAPINFO)lpTempImgData, DIB_RGB_COLORS); if(hPalette && hPrevPalette){
SelectPalette(hDc,hPrevPalette,FALSE);
RealizePalette(hDc);
}    hf=_lcreat(BmpFileName,0);
_lwrite(hf,(LPSTR)&DstBf,sizeof(BITMAPFILEHEADER)); 
_lwrite(hf,(LPSTR)lpTempImgData,DstBufSize);
_lclose(hf); ::ReleaseDC(m_hWnd,hDc);
LocalUnlock(hTempImgData);
LocalFree(hTempImgData);
GlobalUnlock(hImgData);
return TRUE;
}

Answer 2

BOOL LoadBmpFile(LPCSTR BmpFileName)
{
HFILE              hf;
    LPBITMAPINFOHEADER lpImgData;
    LOGPALETTE         *pPal;
    LPRGBQUAD          lpRGB;
    HPALETTE           hPrevPalette; 
    HDC                hDc;
HLOCAL             hPal;
DWORD         ImgSize;
DWORD              i;

    if((hf=_lopen(BmpFileName,OF_READ))==HFILE_ERROR){
        MessageBox("Can not Load file","Error",MB_OK|MB_ICONEXCLAMATION);
        return FALSE;
}
_lread(hf,(LPSTR)&bf,sizeof(BITMAPFILEHEADER)); 
_lread(hf,(LPSTR)&bi,sizeof(BITMAPINFOHEADER));
ImgWidth=bi.biWidth;
ImgHeight=bi.biHeight;
LineBytes=(DWORD)WIDTHBYTES(bi.biWidth*bi.biBitCount);
ImgSize=(DWORD)LineBytes*bi.biHeight;
    if(bi.biClrUsed!=0)
NumColors=(DWORD)bi.biClrUsed;
else
        switch(bi.biBitCount){
case 1:
NumColors=2;
break;
case 4:
NumColors=16;
break;
case 8:
NumColors=256;
break;
case 24:
NumColors=0;
break;
case 32:
NumColors=0;
break;
default:
MessageBox("Invalid color numbers!","Error Message",MB_OK|MB_ICONEXCLAMATION);
_lclose(hf);
return FALSE; 
NumColors = 0;
break;
}

if(bf.bfOffBits!=(DWORD)(NumColors*sizeof(RGBQUAD)+sizeof(BITMAPFILEHEADER)
+sizeof(BITMAPINFOHEADER)))
{
MessageBox("Invalid color numbers!","Error Message" ,MB_OK|
MB_ICONEXCLAMATION);
_lclose(hf);
return FALSE; 
}

bf.bfSize=sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER)+NumColors*sizeof(RGBQUAD)+ImgSize;
if((hImgData=GlobalAlloc(GHND,(DWORD)(sizeof(BITMAPINFOHEADER)+
NumColors*sizeof(RGBQUAD)+ImgSize)))==NULL)
{
MessageBox("Error alloc memory!","ErrorMessage",MB_OK|
MB_ICONEXCLAMATION);
_lclose(hf);
return FALSE;
}

lpImgData=(LPBITMAPINFOHEADER)GlobalLock(hImgData); 
    _llseek(hf,sizeof(BITMAPFILEHEADER),FILE_BEGIN);
_hread(hf,(char *)lpImgData,(long)sizeof(BITMAPINFOHEADER)
+(long)NumColors*sizeof(RGBQUAD)+ImgSize);
_lclose(hf);
    if(NumColors!=0)
{                    
hPal=LocalAlloc(LHND,sizeof(LOGPALETTE) + NumColors* sizeof(PALETTEENTRY));
pPal =(LOGPALETTE *)LocalLock(hPal);
pPal->palNumEntries =(WORD) NumColors;
pPal->palVersion    = 0x300;
lpRGB = (LPRGBQUAD)((LPSTR)lpImgData + (DWORD)sizeof(BITMAPINFOHEADER));
for (i = 0; i < NumColors; i++) {
pPal->palPalEntry[i].peRed=lpRGB->rgbRed;
pPal->palPalEntry[i].peGreen=lpRGB->rgbGreen;
pPal->palPalEntry[i].peBlue=lpRGB->rgbBlue;
pPal->palPalEntry[i].peFlags=(BYTE)0;
lpRGB++;
}
hPalette=CreatePalette(pPal);
LocalUnlock(hPal);
LocalFree(hPal);
}
hDc=::GetDC(m_hWnd);
if(hPalette){
        hPrevPalette=SelectPalette(hDc,hPalette,FALSE);
RealizePalette(hDc);
}
hBitmap=CreateDIBitmap(hDc, (LPBITMAPINFOHEADER)lpImgData, (LONG)CBM_INIT,
(LPSTR)lpImgData+sizeof(BITMAPINFOHEADER) +NumColors*sizeof(RGBQUAD),
(LPBITMAPINFO)lpImgData, DIB_RGB_COLORS);
if(hPalette && hPrevPalette){
SelectPalette(hDc,hPrevPalette,FALSE);
RealizePalette(hDc);
}

::ReleaseDC(m_hWnd,hDc);
GlobalUnlock(hImgData);
GetDocument()->SetTitle( BmpFileName );
return TRUE; 
}

Answer 3

//全局變量
#define WIDTHBYTES(i)    ((i+31)/32*4)
BITMAPFILEHEADER   bf;
BITMAPINFOHEADER   bi;
HPALETTE           hPalette=NULL;
HBITMAP            hBitmap=NULL;
HGLOBAL            hImgData=NULL;
DWORD              NumColors;
DWORD              LineBytes;
HINSTANCE          ghInst;
DWORD              ImgWidth=0 , ImgHeight=0;
int GrayTable[256];
int MaxGrayNum;
int MinGrayNum;
int FirstPoint=0, SecondPoint=255;
float StretchRatio=2.0f;
int EquaScale;

Answer 4

//Usage:
       
if(LoadBmpFile("E:\\Test.bmp"))
{
    ColorToGray("E:\\Gray.bmp");
}