CImage灰度化

BOOL ImageToGray(const CImage& imgSrc, CImage& imgDst)
{
int maxY = imgSrc.GetHeight();
int maxX = imgSrc.GetWidth();

if (!imgDst.IsNull())
{
imgDst.Destroy();
}

imgDst.Create(maxX, maxY, 8, 0);//图像大小与imgSrc相同，每个像素占1字节

//为imgDst构造256阶灰度调色表
RGBQUAD ColorTab[256];
for (int i = 0; i < 256; i++)
{
ColorTab[i].rgbBlue = ColorTab[i].rgbGreen = ColorTab[i].rgbRed = i;
}
imgDst.SetColorTable(0, 256, ColorTab);

//获取指向图像数据的指针
//GetBits 与 GetPitch 关系：
//当GetPitch()<0时，GetBits()获得的指针指向最后一行
//当GetPitch()>0时，GetBits()获得的指针指向第一行

byte* pDataDst = NULL;
byte* pDataSrc = NULL;

if (imgDst.GetPitch() < 0)
pDataDst = (BYTE*)imgDst.GetBits() + (imgDst.GetPitch()*(imgDst.GetHeight() - 1));
else
pDataDst = (BYTE*)imgDst.GetBits();

if (imgSrc.GetPitch() < 0)
pDataSrc = (BYTE*)imgSrc.GetBits() + (imgSrc.GetPitch()*(imgSrc.GetHeight() - 1));
else
pDataSrc = (BYTE*)imgSrc.GetBits();

//获取每行图像占用的字节数
int pitchSrc = abs(imgSrc.GetPitch());
int pitchDst = abs(imgDst.GetPitch());

// 获取每个像素占用的字节数
int bitCountSrc = imgSrc.GetBPP() / 8;

if (bitCountSrc == 1)
{
imgDst = imgSrc;
return TRUE;
}

if ((bitCountSrc != 3) && (bitCountSrc != 4))
return FALSE;

byte tmpR, tmpG, tmpB;
int temGray;

for (int i = 0; i < maxY; i++)
{
for (int j = 0; j < maxX; j++)
{
byte * ptmpSrc = pDataSrc + pitchSrc*i + j*bitCountSrc;
tmpB = *ptmpSrc++;
tmpG = *ptmpSrc++;
tmpR = *ptmpSrc;

temGray = (tmpR * 19595 + tmpG * 38469 + tmpB * 7472) >> 16;
*(pDataDst + pitchDst*i + j) = temGray;
}
}

return TRUE;
}