浮点矩阵上的指针被视为* uchar

Question

I'm trying to iterare trough a cv::Mat with a pointer. So I did the following in my function:

template<typename Tin=uchar,typename Tout=float>
inline cv::Mat_<Tout> dct(const cv::Mat_<Tin>& oBlock) {

    cv::Mat_<Tout> oOutput(oBlock.size());
    Tout *pointeurOut= oOutput.data; 

    //...
}

However, I'm getting an error at the last line ( Tout *pointeurOut= oOutput.data; ).

'initializing': cannot convert from 'uchar *' to 'float *'

Where does that come from?

Answer 1

data is always a uchar* .

You should use

oOutput.ptr<Tout>(); 

to get the Tout pointer to the i-th row (by default is the 0-th row, ie the beginning of the image)