opencv学习笔记-入门（7）单通道的图像数据访问

4） 基于指针的直接访问: (简单高效)

int height     = img->height;
int width      = img->width;
int step       = img->widthStep;
uchar* data    = (uchar *)img->imageData;
data[i*step+j] = 111;</pre><br><span style="color:rgb(51,153,51)"></span>

int height     = img->height;
int width      = img->width;
int step       = img->widthStep;
int channels   = img->nChannels;
uchar* data    = (uchar *)img->imageData;
data[i*step+j*channels+k] = 111;</pre><br><span style="color:rgb(51,153,51)"></span>

{
uchar *sptr = src->data.ptr + src->step*y;
uchar *pDataOutput = dst->data.ptr + src->step*y;
for(int x = 0; x < size.width; x++, pDataOutput++, sptr+=Nds)
{
for(int iD = 0; iD < Nds; iD++)
{
data[iD] = sqrt(float(sptr[iD]));

}
}
}    </pre><br><br>