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// Copyright (C) 2013, Alfonso Sanchez-Beato, all rights reserved.
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#ifndef MAPPER_H_
#define MAPPER_H_

#include <opencv2/core.hpp> // Basic OpenCV structures (cv::Mat, Scalar)
#include "map.hpp"

namespace cv {
namespace reg {

//! @addtogroup reg
//! @{

/** @brief Base class for modelling an algorithm for calculating a map

The class is only used to define the common interface for any possible mapping algorithm.
 */
class CV_EXPORTS_W Mapper
{
public:
    virtual ~Mapper(void) {}

    /*
     * Calculate mapping between two images
     * \param[in] img1 Reference image
     * \param[in] img2 Warped image
     * \param[in] If present, it is an initial rough estimation that the mapper will try to refine.
     * \return Map from img1 to img2, stored in a smart pointer.
     */
    CV_WRAP virtual cv::Ptr<Map> calculate(InputArray img1, InputArray img2, cv::Ptr<Map> init = cv::Ptr<Map>()) const = 0;

    /*
     * Returns a map compatible with the Mapper class
     * \return Pointer to identity Map
     */
    CV_WRAP virtual cv::Ptr<Map> getMap() const = 0;

protected:
    /*
     * Calculates gradient and difference between images
     * \param[in] img1 Image one
     * \param[in] img2 Image two
     * \param[out] Ix Gradient x-coordinate
     * \param[out] Iy Gradient y-coordinate
     * \param[out] It Difference of images
     */
    void gradient(const cv::Mat& img1, const cv::Mat& img2,
                  cv::Mat& Ix, cv::Mat& Iy, cv::Mat& It) const;

    /*
     * Fills matrices with pixel coordinates of an image
     * \param[in] img Image
     * \param[out] grid_r Row (y-coordinate)
     * \param[out] grid_c Column (x-coordinate)
     */
    void grid(const Mat& img, Mat& grid_r, Mat& grid_c) const;

    /*
     * Per-element square of a matrix
     * \param[in] mat1 Input matrix
     * \return mat1[i,j]^2
     */
    cv::Mat sqr(const cv::Mat& mat1) const
    {
        cv::Mat res;
        res.create(mat1.size(), mat1.type());
        res = mat1.mul(mat1);
        return res;
    }
};

//! @}

}}  // namespace cv::reg

#endif  // MAPPER_H_