// 索引图像转灰度图像
bool CImg::Index2Gray()
{
int i;
if (!IsIndexedImg()) return false;
RGBQUAD *table = (RGBQUAD*)m_lpvColorTable;
m_pBMIH->biBitCount = 8;
// 更新颜色数据
for (i=0; i<GetHeight(); i++)
{
for (int j=0; j<GetWidthPixel(); j++)
{
RGBQUAD rgb = *(table+GetGray(j, i));
BYTE gray = rgb.rgbBlue * 0.114 + rgb.rgbGreen * 0.587 + rgb.rgbRed * 0.299 + 0.5;
SetPixel(j, i, RGB(gray, gray, gray));
}
}
// 更新颜色表
for (i=0; i<256; i++)
{
(table + i)->rgbBlue = i;
(table + i)->rgbGreen = i;
(table + i)->rgbRed = i;
(table + i)->rgbReserved = 0;
}
m_nColorTableEntries = 256;
return true;
}
byte *tga_t::GrabData(byte *buff, int size)
{
if (bits == 32)
return GetRGBA (buff, size);
else if (bits == 24)
return GetRGB (buff, size);
else if (bits == 8)
return GetGray (buff, size);
return 0;
}
CImg CImg::operator ! ()
{
CImg grayRet = *this;
grayRet.InitPixels(255); //结果图像置白
int nHeight = GetHeight();
int nWidth = GetWidthPixel();
int i,j;
for(i=0; i<nHeight; i++)
{
for(j=0; j<nWidth; j++)
{
int pixel = 255 - GetGray(j, i);
grayRet.SetPixel(j, i, RGB(pixel, pixel, pixel));
}
}
return grayRet;
}
BOOL CImg::operator == (CImg& gray)
{
int nHeight = GetHeight();
int nWidth = GetWidthPixel();
if(nHeight != gray.GetHeight())
return false;
if(nWidth != gray.GetWidthPixel())
return false;
for(int i=0; i<nHeight; i++)
{
for(int j=0; j<nWidth; j++)
{
if( GetGray(j, i) != gray.GetGray(j, i) )
return false;
}
}
return true;
}
HRESULT CImage::GetGrayF(float x, float y, int nBand, BYTE* pGray, int nResampleMethod)
{
if(m_pGdalImage==NULL&&m_fpRaws==NULL)
{
return S_FALSE;
}
if(nResampleMethod == 0)
{
int nCol, nRow;
nCol = int(x + 0.5);
nRow = int(y + 0.5);
if(nCol >= 0 && nCol < m_nCols && nRow >= 0 && nRow < m_nRows)
{
GetGray(nRow,nCol,nBand,pGray);
}
else
{
memset(pGray,0,m_nBPB);
}
}
else
{
int nCol1, nCol2, nRow1, nRow2;
float Dx, Dy;
static BYTE pBuf11[512], pBuf12[512], pBuf21[512], pBuf22[512]; //, pBufDest[512];
nCol1 = int(x);
nRow1 = int(y);
nCol2 = nCol1 + 1;
nRow2 = nRow1 + 1;
//be sure the second pixel in image
nCol2=__min(nCol2,m_nCols-1);
nRow2=__min(nRow2,m_nRows-1);
Dx = x - nCol1;
Dy = y - nRow1;
UINT nDataType;
GetDataType(&nDataType);
int nBPB;
GetBPB(&nBPB);
if(nRow1 >= 0 && nRow1 < m_nRows && nCol1 >= 0 && nCol1 < m_nCols)
{
GetGray(nRow1,nCol1,nBand,pBuf11);
GetGray(nRow1,nCol2,nBand,pBuf21);
GetGray(nRow2,nCol1,nBand,pBuf12);
GetGray(nRow2,nCol2,nBand,pBuf22);
(* FuncTable_GDAL[nDataType])(pBuf11,
pBuf21,
pBuf22,
pBuf12,
Dx,Dy,
pGray);
}
else
{
memset(pGray,0,nBPB);
}
}
return S_OK;
}
/*******************
CImg CImg::operator - (CImg gray)
功能：图像按位减
参数：
CImg 对象
返回值:
CImg： 相减后的 CImg 类图像对象
*******************/
CImg CImg::operator - (CImg &gray)
{
CImg grayRet = *this; //返回图像
//取得图像的高和宽
int nHeight = GetHeight();
int nWidth = GetWidthPixel();
int i, j;//循环变量
//不能在CImg类对象中直接进行像素相减，因为相减的结果可能小于0
vector< vector<int> > GrayMat;//相减后暂存图像的灰度点阵
vector<int> vecRow(nWidth, 0); //GrayMat中的一行（初始化为0）
for(i=0; i<nHeight; i++)
{
GrayMat.push_back(vecRow);
}
//最大、最小灰度和值
int nMax = -255;
int nMin = 255;
//逐行扫描图像
for(i=0; i<nHeight; i++)
{
for(j=0; j<nWidth; j++)
{
//按位相加
GrayMat[i][j] = GetGray(j, i) - gray.GetGray(j, i);
//统计最大、最小值
if( GrayMat[i][j] > nMax)
nMax = GrayMat[i][j];
if( GrayMat[i][j] < nMin)
nMin = GrayMat[i][j];
}// j
}// i
//将GrayMat的取值范围重新归一化到[0, 255]
int nSpan = nMax - nMin;
for(i=0; i<nHeight; i++)
{
for(j=0; j<nWidth; j++)
{
BYTE bt;
if(nSpan > 0)
bt = (GrayMat[i][j] - nMin)*255/nSpan;
else if(GrayMat[i][j] <= 255)
bt = GrayMat[i][j] ;
else
bt = 255;
grayRet.SetPixel(j, i, RGB(bt, bt, bt));
}// for j
}// for i
return grayRet;
}
