pct_sampler.cpp

/*
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/*
Contributed by Gregor Kovalcik <gregor dot kovalcik at gmail dot com>
    based on code provided by Martin Krulis, Jakub Lokoc and Tomas Skopal.

References:
    Martin Krulis, Jakub Lokoc, Tomas Skopal.
    Efficient Extraction of Clustering-Based Feature Signatures Using GPU Architectures.
    Multimedia tools and applications, 75(13), pp.: 8071–8103, Springer, ISSN: 1380-7501, 2016

    Christian Beecks, Merih Seran Uysal, Thomas Seidl.
    Signature quadratic form distance.
    In Proceedings of the ACM International Conference on Image and Video Retrieval, pages 438-445.
    ACM, 2010.
*/

#include "../precomp.hpp"

#include "pct_sampler.hpp"

namespace cv
{
    namespace xfeatures2d
    {
        namespace pct_signatures
        {
            class PCTSampler_Impl : public PCTSampler
            {
            private:
                /**
                * @brief Initial sampling point coordinates.
                */
                std::vector<Point2f> mInitSamplingPoints;

                /**
                * @brief Number of bits per pixel in grayscale image used for computing contrast and entropy.
                */
                int mGrayscaleBits;

                /**
                * @brief Radius of scanning window around a sampled point used for computing contrast and entropy.
                */
                int mWindowRadius;

                /**
                * @brief Weights of different feauture dimensions.
                *       Default values are 1;
                */
                std::vector<float> mWeights;

                /**
                * @brief Translation of different feauture dimensions.
                *       Default values are 0;
                */
                std::vector<float> mTranslations;


            public:

                PCTSampler_Impl(
                    const std::vector<Point2f>& initSamplingPoints,
                    int grayscaleBits,
                    int windowRadius)
                    : mInitSamplingPoints(initSamplingPoints),
                    mGrayscaleBits(grayscaleBits),
                    mWindowRadius(windowRadius)
                {
                    // Initialize weights and translation vectors to neutral values.
                    for (int i = 0; i < SIGNATURE_DIMENSION; i++)
                    {
                        mWeights.push_back(1.0);
                        mTranslations.push_back(0.0);
                    }
                }


                /**** Acessors ****/

                int getSampleCount() const      { return (int)mInitSamplingPoints.size(); }
                int getGrayscaleBits() const    { return mGrayscaleBits; }
                int getWindowRadius() const     { return mWindowRadius; }

                float getWeightX() const               { return mWeights[X_IDX]; }
                float getWeightY() const               { return mWeights[Y_IDX]; }
                float getWeightL() const               { return mWeights[L_IDX]; }
                float getWeightA() const               { return mWeights[A_IDX]; }
                float getWeightB() const               { return mWeights[B_IDX]; }
                float getWeightConstrast() const       { return mWeights[CONTRAST_IDX]; }
                float getWeightEntropy() const         { return mWeights[ENTROPY_IDX]; }

                std::vector<Point2f> getSamplingPoints() const
                                                        { return mInitSamplingPoints; }


                void setGrayscaleBits(int grayscaleBits)    { mGrayscaleBits = grayscaleBits; }
                void setWindowRadius(int windowRadius)      { mWindowRadius = windowRadius; }

                void setWeightX(float weight)          { mWeights[X_IDX] = weight; }
                void setWeightY(float weight)          { mWeights[Y_IDX] = weight; }
                void setWeightL(float weight)          { mWeights[L_IDX] = weight; }
                void setWeightA(float weight)          { mWeights[A_IDX] = weight; }
                void setWeightB(float weight)          { mWeights[B_IDX] = weight; }
                void setWeightContrast(float weight)   { mWeights[CONTRAST_IDX] = weight; }
                void setWeightEntropy(float weight)    { mWeights[ENTROPY_IDX] = weight; }


                void setWeight(int idx, float value)
                {
                    mWeights[idx] = value;
                }

                void setWeights(const std::vector<float>& weights)
                {
                    if (weights.size() != mWeights.size())
                    {
                        CV_Error_(Error::StsUnmatchedSizes,
                            ("Invalid weights dimension %d (max %d)", weights.size(), mWeights.size()));
                    }
                    else
                    {
                        for (int i = 0; i < (int)(mWeights.size()); ++i)
                        {
                            mWeights[i] = weights[i];
                        }
                    }
                }

                void setTranslation(int idx, float value)
                {
                    mTranslations[idx] = value;
                }

                void setTranslations(const std::vector<float>& translations)
                {
                    if (translations.size() != mTranslations.size())
                    {
                        CV_Error_(Error::StsUnmatchedSizes,
                            ("Invalid translations dimension %d (max %d)", translations.size(), mTranslations.size()));
                    }
                    else
                    {
                        for (int i = 0; i < (int)(mTranslations.size()); ++i)
                        {
                            mTranslations[i] = translations[i];
                        }
                    }
                }

                void setSamplingPoints(std::vector<Point2f> samplingPoints) { mInitSamplingPoints = samplingPoints; }


                void sample(InputArray _image, OutputArray _samples) const
                {
                    // prepare matrices
                    Mat image = _image.getMat();
                    _samples.create((int)(mInitSamplingPoints.size()), SIGNATURE_DIMENSION, CV_32F);
                    Mat samples = _samples.getMat();
                    GrayscaleBitmap grayscaleBitmap(image, mGrayscaleBits);

                    // sample each sample point
                    for (int iSample = 0; iSample < (int)(mInitSamplingPoints.size()); iSample++)
                    {
                        // sampling points are in range [0..1)
                        int x = (int)(mInitSamplingPoints[iSample].x * (image.cols));
                        int y = (int)(mInitSamplingPoints[iSample].y * (image.rows));

                        // x, y normalized
                        samples.at<float>(iSample, X_IDX) = (float)((float)x / (float)image.cols * mWeights[X_IDX] + mTranslations[X_IDX]);
                        samples.at<float>(iSample, Y_IDX) = (float)((float)y / (float)image.rows * mWeights[Y_IDX] + mTranslations[Y_IDX]);

                        // get Lab pixel color
                        Mat rgbPixel(image, Rect(x, y, 1, 1));
                        Mat labPixel;
                        rgbPixel.convertTo(rgbPixel, CV_32FC3, 1.0 / 255);
                        cvtColor(rgbPixel, labPixel, COLOR_BGR2Lab);
                        Vec3f labColor = labPixel.at<Vec3f>(0, 0);

                        // Lab color normalized
                        samples.at<float>(iSample, L_IDX) = (float)(std::floor(labColor[0] + 0.5) / L_COLOR_RANGE * mWeights[L_IDX] + mTranslations[L_IDX]);
                        samples.at<float>(iSample, A_IDX) = (float)(std::floor(labColor[1] + 0.5) / A_COLOR_RANGE * mWeights[A_IDX] + mTranslations[A_IDX]);
                        samples.at<float>(iSample, B_IDX) = (float)(std::floor(labColor[2] + 0.5) / B_COLOR_RANGE * mWeights[B_IDX] + mTranslations[B_IDX]);

                        // contrast and entropy
                        float contrast = 0.0, entropy = 0.0;
                        grayscaleBitmap.getContrastEntropy(x, y, contrast, entropy, mWindowRadius);     // HOT PATH: 30%
                        samples.at<float>(iSample, CONTRAST_IDX)
                            = (float)(contrast / SAMPLER_CONTRAST_NORMALIZER * mWeights[CONTRAST_IDX] + mTranslations[CONTRAST_IDX]);
                        samples.at<float>(iSample, ENTROPY_IDX)
                            = (float)(entropy / SAMPLER_ENTROPY_NORMALIZER * mWeights[ENTROPY_IDX] + mTranslations[ENTROPY_IDX]);
                    }
                }

            };


            Ptr<PCTSampler> PCTSampler::create(
                const std::vector<Point2f>& initPoints,
                int                         grayscaleBits,
                int                         windowRadius)
            {
                return makePtr<PCTSampler_Impl>(initPoints, grayscaleBits, windowRadius);
            }
        }
    }
}