ImageTransformation.cpp

#include "ImageTransformation.hpp"

bool ImageTransformation::canTransformKeypoints() const
{
    return false;
}

void ImageTransformation::transform(float t, const Keypoints& source, Keypoints& result) const
{

}

cv::Mat ImageTransformation::getHomography(float t, const cv::Mat& source) const
{
    return cv::Mat::eye(3, 3, CV_64FC1);
}


ImageTransformation::~ImageTransformation()
{
}

bool ImageTransformation::findHomography( const Keypoints& source, const Keypoints& result, const Matches& input, Matches& inliers, cv::Mat& homography)
{
    if (input.size() < 4)
        return false;
    
    const int pointsCount = input.size();
    const float reprojectionThreshold = 2;

    //Prepare src and dst points
    std::vector<cv::Point2f> srcPoints, dstPoints;    
    for (int i = 0; i < pointsCount; i++)
    {
        srcPoints.push_back(source[input[i].trainIdx].pt);
        dstPoints.push_back(result[input[i].queryIdx].pt);
    }
      
    // Find homography using RANSAC algorithm
    std::vector<unsigned char> status;
    homography = cv::findHomography(srcPoints, dstPoints, cv::RANSAC, reprojectionThreshold, status);
    
    // Warp dstPoints to srcPoints domain using inverted homography transformation
    std::vector<cv::Point2f> srcReprojected;
    cv::perspectiveTransform(dstPoints, srcReprojected, homography.inv());

    // Pass only matches with low reprojection error (less than reprojectionThreshold value in pixels)
    inliers.clear();
    for (int i = 0; i < pointsCount; i++)
    {
        cv::Point2f actual = srcPoints[i];
        cv::Point2f expect = srcReprojected[i];
        cv::Point2f v = actual - expect;
        float distanceSquared = v.dot(v);
        
        if (/*status[i] && */distanceSquared <= reprojectionThreshold * reprojectionThreshold)
        {
            inliers.push_back(input[i]);
        }
    }
    
    // Test for bad case
    if (inliers.size() < 4)
        return false;
    
    // Now use only good points to find refined homography:
    std::vector<cv::Point2f> refinedSrc, refinedDst;
    for (int i = 0; i < inliers.size(); i++)
    {
        refinedSrc.push_back(source[inliers[i].trainIdx].pt);
        refinedDst.push_back(result[inliers[i].queryIdx].pt);
    }
    
    // Use least squares method to find precise homography
    cv::Mat homography2 = cv::findHomography(refinedSrc, refinedDst, 0, reprojectionThreshold);

    // Reproject again:
    cv::perspectiveTransform(dstPoints, srcReprojected, homography2.inv());
    inliers.clear();

    for (int i = 0; i < pointsCount; i++)
    {
        cv::Point2f actual = srcPoints[i];
        cv::Point2f expect = srcReprojected[i];
        cv::Point2f v = actual - expect;
        float distanceSquared = v.dot(v);

        if (distanceSquared <= reprojectionThreshold * reprojectionThreshold)
        {
            inliers.push_back(input[i]);
        }
    }
 
    homography = homography2;
    return inliers.size() >= 4;
}

#pragma mark - ImageRotationTransformation implementation

ImageRotationTransformation::ImageRotationTransformation(float startAngleInDeg, float endAngleInDeg, float step, cv::Point2f rotationCenterInUnitSpace)
: ImageTransformation("Rotation")
, m_startAngleInDeg(startAngleInDeg)
, m_endAngleInDeg(endAngleInDeg)
, m_step(step)
, m_rotationCenterInUnitSpace(rotationCenterInUnitSpace)
{
    // Fill the arguments
    for (float arg = startAngleInDeg; arg <= endAngleInDeg; arg += step)
        m_args.push_back(arg);
}

std::vector<float> ImageRotationTransformation::getX() const
{
    return m_args;
}

void ImageRotationTransformation::transform(float t, const cv::Mat& source, cv::Mat& result) const
{
    cv::Point2f center(source.cols * m_rotationCenterInUnitSpace.x, source.rows * m_rotationCenterInUnitSpace.y);
    cv::Mat rotationMat = cv::getRotationMatrix2D(center, t, 1);
    cv::warpAffine(source, result, rotationMat, source.size(), cv::INTER_CUBIC);
}

cv::Mat ImageRotationTransformation::getHomography(float t, const cv::Mat& source) const
{
    cv::Point2f center(source.cols * m_rotationCenterInUnitSpace.x, source.rows * m_rotationCenterInUnitSpace.y);
    cv::Mat rotationMat = cv::getRotationMatrix2D(center, t, 1);
    
    cv::Mat h = cv::Mat::eye(3,3, CV_64FC1);
    rotationMat.copyTo(h(cv::Range(0,2), cv::Range(0,3)));
    return h;
}


#pragma mark - ImageScalingTransformation implementation

ImageScalingTransformation::ImageScalingTransformation(float minScale, float maxScale, float step)
: ImageTransformation("Scaling")
, m_minScale(minScale)
, m_maxScale(maxScale)
, m_step(step)
{
    // Fill the arguments
    for (float arg = minScale; arg <= maxScale; arg += step)
        m_args.push_back(arg);
}

std::vector<float> ImageScalingTransformation::getX() const
{
    return m_args;
}

void ImageScalingTransformation::transform(float t, const cv::Mat& source, cv::Mat& result)const
{
    cv::Size dstSize(static_cast<int>(source.cols * t + 0.5f), static_cast<int>(source.rows * t + 0.5f));
    cv::resize(source, result, dstSize, cv::INTER_AREA);
}

cv::Mat ImageScalingTransformation::getHomography(float t, const cv::Mat& source) const
{
    cv::Mat h = cv::Mat::eye(3,3, CV_64FC1);
    h.at<double>(0,0) = h.at<double>(1,1) = t;
    return h;
}

#pragma mark - GaussianBlurTransform implementation

GaussianBlurTransform::GaussianBlurTransform(int maxKernelSize)
: ImageTransformation("Gaussian blur")
, m_maxKernelSize(maxKernelSize)
{
    for (int arg = 1; arg <= maxKernelSize; arg++)
        m_args.push_back(static_cast<float>(arg));
}

std::vector<float> GaussianBlurTransform::getX() const
{
    return m_args;
}

void GaussianBlurTransform::transform(float t, const cv::Mat& source, cv::Mat& result)const
{
    int kernelSize = static_cast<int>(t) * 2 + 1;
    cv::GaussianBlur(source, result, cv::Size(kernelSize,kernelSize), 0);
}

#pragma mark - BrightnessImageTransform implementation

BrightnessImageTransform::BrightnessImageTransform(int min, int max, int step)
: ImageTransformation("Brightness change")
, m_min(min)
, m_max(max)
, m_step(step)
{
    for (int arg = min; arg <= max; arg += step)
        m_args.push_back(static_cast<float>(arg));
}

std::vector<float> BrightnessImageTransform::getX() const
{
    return m_args;
}

void BrightnessImageTransform::transform(float t, const cv::Mat& source, cv::Mat& result)const
{
    result = source + cv::Scalar(t,t,t,t);
}

#pragma mark - CombinedTransform implementation

CombinedTransform::CombinedTransform(cv::Ptr<ImageTransformation> first, cv::Ptr<ImageTransformation> second, ParamCombinationType type)
: ImageTransformation(first->name + "+" + second->name)
, m_first(first)
, m_second(second)
{
    std::vector<float> x1 = first->getX();
    std::vector<float> x2 = second->getX();
    
    switch (type)
    {
        case Full:
        {
            int index = 0;
            for (size_t i1 = 0; i1 < x1.size(); i1++)
            {
                for (size_t i2 = 0; i2 < x2.size(); i2++)
                {
                    m_params.push_back(std::make_pair(x1[i1], x2[i2]));
                    m_x.push_back(index);
                    index++;
                }
            }
        }
        break;
            
            
        case Interpolate:
        {
            if (x1.size() > x2.size())
            {
                int index = 0;
                for (size_t i2 = 0; i2 < x2.size(); i2++)
                {
                    size_t i1 = static_cast<size_t>((float)(x1.size() * i2) / (float)x2.size() + 0.5f);
                    m_params.push_back(std::make_pair(x1[i1], x2[i2]));
                    m_x.push_back(index);
                    index++;
                }
            }
            else
            {
                int index = 0;
                for (size_t i1 = 0; i1 < x1.size(); i1++)
                {
                    size_t i2 = static_cast<size_t>((float)(x2.size() * i1) / (float)x1.size() + 0.5f);
                    m_params.push_back(std::make_pair(x1[i1], x2[i2]));
                    m_x.push_back(index);
                    index++;
                }                
            }
            

        }; break;
            
            
        case Extrapolate:
        {
            if (x1.size() > x2.size())
            {
                int index = 0;
                for (size_t i1 = 0; i1 < x1.size(); i1++)
                {
                    size_t i2 = static_cast<size_t>((float)(x2.size() * i1) / (float)x1.size() );
                    m_params.push_back(std::make_pair(x1[i1], x2[i2]));
                    m_x.push_back(index);
                    index++;
                }
            }
            else
            {
                int index = 0;
                for (size_t i2 = 0; i2 < x2.size(); i2++)
                {
                    size_t i1 = static_cast<size_t>((float)(x1.size() * i2) / (float)x2.size() );
                    m_params.push_back(std::make_pair(x1[i1], x2[i2]));
                    m_x.push_back(index);
                    index++;
                }
            }
        }; break;
            
        default:
            break;
    };
}

std::vector<float> CombinedTransform::getX() const
{
    return m_x;
}

void CombinedTransform::transform(float t, const cv::Mat& source, cv::Mat& result) const
{
    size_t index = static_cast<size_t>(t);
    float t1 = m_params[index].first;
    float t2 = m_params[index].second;
    
    cv::Mat temp;
    m_first->transform(t1, source, temp);
    m_second->transform(t2, temp, result);
}

bool CombinedTransform::canTransformKeypoints() const
{
    return m_first->canTransformKeypoints() && m_second->canTransformKeypoints();
}

void CombinedTransform::transform(float t, const Keypoints& source, Keypoints& result) const
{
    size_t index = static_cast<size_t>(t);
    float t1 = m_params[index].first;
    float t2 = m_params[index].second;
    
    Keypoints temp;
    m_first->transform(t1, source, temp);
    m_second->transform(t2, temp, result);
    
}

cv::Mat CombinedTransform::getHomography(float t, const cv::Mat& source) const
{
    size_t index = static_cast<size_t>(t);
    
    float t1 = m_params[index].first;
    float t2 = m_params[index].second;

    cv::Mat temp;
    m_first->transform(t1, source, temp);

    return m_second->getHomography(t2, temp) * m_first->getHomography(t1, source);
}

#pragma mark PerspectiveTransform implementation

PerspectiveTransform::PerspectiveTransform(int count)
: ImageTransformation("Perspective")
{
    cv::RNG rng;
    
    for (int i=0; i<count; i++)
    {
        m_args.push_back(i);
        m_homographies.push_back(warpPerspectiveRand(rng));
    }
}

cv::Mat PerspectiveTransform::warpPerspectiveRand( cv::RNG& rng )
{
    cv::Mat H;
    
    H.create(3, 3, CV_64FC1);
    H.at<double>(0,0) = rng.uniform( 0.8f, 1.2f);
    H.at<double>(0,1) = rng.uniform(-0.1f, 0.1f);
    //H.at<double>(0,2) = rng.uniform(-0.1f, 0.1f)*src.cols;
    H.at<double>(0,2) = rng.uniform(-0.1f, 0.1f);
    H.at<double>(1,0) = rng.uniform(-0.1f, 0.1f);
    H.at<double>(1,1) = rng.uniform( 0.8f, 1.2f);
    //H.at<double>(1,2) = rng.uniform(-0.1f, 0.1f)*src.rows;
    H.at<double>(1,2) = rng.uniform(-0.1f, 0.1f);
    H.at<double>(2,0) = rng.uniform( -1e-4f, 1e-4f);
    H.at<double>(2,1) = rng.uniform( -1e-4f, 1e-4f);
    H.at<double>(2,2) = rng.uniform( 0.8f, 1.2f);

    return H;
}

std::vector<float> PerspectiveTransform::getX() const
{
    return m_args;
}

void PerspectiveTransform::transform(float t, const cv::Mat& source, cv::Mat& result) const
{
    cv::warpPerspective(source, result, getHomography(t, source), source.size(), cv::INTER_CUBIC);
}

cv::Mat PerspectiveTransform::getHomography(float t, const cv::Mat& source) const
{
    cv::Mat h = m_homographies[(int)t].clone();
    
    h.at<double>(0,2) *= source.cols;
    h.at<double>(1,2) *= source.rows;

    return h;
}
