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#ifndef __OPENCV_STITCHING_EXPOSURE_COMPENSATE_HPP__
#define __OPENCV_STITCHING_EXPOSURE_COMPENSATE_HPP__

#include "opencv2/core.hpp"

namespace cv {
namespace detail {

//! @addtogroup stitching_exposure
//! @{

/** @brief Base class for all exposure compensators.
 */
class CV_EXPORTS ExposureCompensator
{
public:
    virtual ~ExposureCompensator() {}

    enum { NO, GAIN, GAIN_BLOCKS };
    static Ptr<ExposureCompensator> createDefault(int type);

    /**
    @param corners Source image top-left corners
    @param images Source images
    @param masks Image masks to update (second value in pair specifies the value which should be used
    to detect where image is)
     */
    void feed(const std::vector<Point> &corners, const std::vector<UMat> &images,
              const std::vector<UMat> &masks);
    /** @overload */
    virtual void feed(const std::vector<Point> &corners, const std::vector<UMat> &images,
                      const std::vector<std::pair<UMat,uchar> > &masks) = 0;
    /** @brief Compensate exposure in the specified image.

    @param index Image index
    @param corner Image top-left corner
    @param image Image to process
    @param mask Image mask
     */
    virtual void apply(int index, Point corner, InputOutputArray image, InputArray mask) = 0;
};

/** @brief Stub exposure compensator which does nothing.
 */
class CV_EXPORTS NoExposureCompensator : public ExposureCompensator
{
public:
    void feed(const std::vector<Point> &/*corners*/, const std::vector<UMat> &/*images*/,
              const std::vector<std::pair<UMat,uchar> > &/*masks*/) { }
    void apply(int /*index*/, Point /*corner*/, InputOutputArray /*image*/, InputArray /*mask*/) { }
};

/** @brief Exposure compensator which tries to remove exposure related artifacts by adjusting image
intensities, see @cite BL07 and @cite WJ10 for details.
 */
class CV_EXPORTS GainCompensator : public ExposureCompensator
{
public:
    void feed(const std::vector<Point> &corners, const std::vector<UMat> &images,
              const std::vector<std::pair<UMat,uchar> > &masks);
    void apply(int index, Point corner, InputOutputArray image, InputArray mask);
    std::vector<double> gains() const;

private:
    Mat_<double> gains_;
};

/** @brief Exposure compensator which tries to remove exposure related artifacts by adjusting image block
intensities, see @cite UES01 for details.
 */
class CV_EXPORTS BlocksGainCompensator : public ExposureCompensator
{
public:
    BlocksGainCompensator(int bl_width = 32, int bl_height = 32)
            : bl_width_(bl_width), bl_height_(bl_height) {}
    void feed(const std::vector<Point> &corners, const std::vector<UMat> &images,
              const std::vector<std::pair<UMat,uchar> > &masks);
    void apply(int index, Point corner, InputOutputArray image, InputArray mask);

private:
    int bl_width_, bl_height_;
    std::vector<UMat> gain_maps_;
};

//! @}

} // namespace detail
} // namespace cv

#endif // __OPENCV_STITCHING_EXPOSURE_COMPENSATE_HPP__
