Preprocess.cpp

// Preprocess.cpp

#include "Preprocess.h"

///////////////////////////////////////////////////////////////////////////////////////////////////
void preprocess(cv::Mat &imgOriginal, cv::Mat &imgGrayscale, cv::Mat &imgThresh) {
    imgGrayscale = extractValue(imgOriginal);                           // extract value channel only from original image to get imgGrayscale

    cv::Mat imgMaxContrastGrayscale = maximizeContrast(imgGrayscale);       // maximize contrast with top hat and black hat

    cv::Mat imgBlurred;

    cv::GaussianBlur(imgMaxContrastGrayscale, imgBlurred, GAUSSIAN_SMOOTH_FILTER_SIZE, 0);          // gaussian blur

                                                                                                    // call adaptive threshold to get imgThresh
    cv::adaptiveThreshold(imgBlurred, imgThresh, 255.0, CV_ADAPTIVE_THRESH_GAUSSIAN_C, CV_THRESH_BINARY_INV, ADAPTIVE_THRESH_BLOCK_SIZE, ADAPTIVE_THRESH_WEIGHT);
}

///////////////////////////////////////////////////////////////////////////////////////////////////
cv::Mat extractValue(cv::Mat &imgOriginal) {
    cv::Mat imgHSV;
    std::vector<cv::Mat> vectorOfHSVImages;
    cv::Mat imgValue;

    cv::cvtColor(imgOriginal, imgHSV, CV_BGR2HSV);

    cv::split(imgHSV, vectorOfHSVImages);

    imgValue = vectorOfHSVImages[2];

    return(imgValue);
}

///////////////////////////////////////////////////////////////////////////////////////////////////
cv::Mat maximizeContrast(cv::Mat &imgGrayscale) {
    cv::Mat imgTopHat;
    cv::Mat imgBlackHat;
    cv::Mat imgGrayscalePlusTopHat;
    cv::Mat imgGrayscalePlusTopHatMinusBlackHat;

    cv::Mat structuringElement = cv::getStructuringElement(CV_SHAPE_RECT, cv::Size(3, 3));

    cv::morphologyEx(imgGrayscale, imgTopHat, CV_MOP_TOPHAT, structuringElement);
    cv::morphologyEx(imgGrayscale, imgBlackHat, CV_MOP_BLACKHAT, structuringElement);

    imgGrayscalePlusTopHat = imgGrayscale + imgTopHat;
    imgGrayscalePlusTopHatMinusBlackHat = imgGrayscalePlusTopHat - imgBlackHat;

    return(imgGrayscalePlusTopHatMinusBlackHat);
}