CODEWITHSUNDEEP
c++opencv
StereoMatching
StereoMatching

Reputation: 5019

Type casting on the data pointer of openCV

codes 1

template<typename T>
inline T* get_pointer(cv::Mat &src, int row)
{
    return src.ptr<T>(row);
}

template<typename T>
inline T* get_pointer(cv::Mat &src, int row, int col)
{
    return get_pointer<T>(src, row) + col * src.channels();
}

template<typename T>
inline T* get_pointer(cv::Mat &src, int row, int col, int channel)
{
    return get_pointer<T>(src, row, col) + channel;
}

codes 2

cv::Mat input = //....
auto *input_ptr = get_pointer<float>(input, row, col);
//back to previous row
input_ptr = reinterpret_cast<float*>(reinterpret_cast<uchar*>(input_ptr) - input.steps);

Are they safe?

Upvotes: 1

Views: 1687

Answers (1)

Sameer
Sameer

Reputation: 2525

Why don't you use this (shorter and safer) code instead?

T *ptr_to_elem = &src.at<T>(row,col)[channel];

This works for non-contiguous arrays too. No potentially dangerous reinterpret_cast<> needed. The only condition for safety here is that you know the datatype T. A more safe version is when you use cv::Mat_<T> instead of cv::Mat, so that mistakes are caught at compile time instead of crashing your program at run time.

T *ptr_to_elem = &src(row,col)[channel];

Upvotes: 1

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