C++ 调节图像饱和度

BYTE bySaturationMap[256*256];

//滚动条0-255
//......
CreateSaturationMap(m_saturationctl.GetPos());
//......

void CreateSaturationMap(BYTE value)
{
    int nTmp;
    for (int g=0; g<256; ++g)
    {
        for (int i=0; i<256; ++i)
        {
            nTmp = g+ value*(i-g)/128;
            nTmp = min(255, max(0, nTmp));
            bySaturationMap[g*256+i] = nTmp;
        }
    }
}
void Img_ISP(BYTE* pData, int wid, int hei)
{
                int g, r, b;
     BYTE *pNode = NULL;
    
    pNode = pData;
    for (int j=0; j<hei; j++)
    {
        for (int i=0; i<wid; i++)
        {
            r = *pNode;
            g = *(pNode+1);
            b = *(pNode+2);    
            *pNode       = bySaturationMap[g*256+r];
            *(pNode+2) = bySaturationMap[g*256+b];
            pNode = pNode+3;
        }
    }
}