From db4ee4889f69fcfef4326ee6b28d2beb1954899b Mon Sep 17 00:00:00 2001 From: Frederico Lopes Date: Wed, 18 Mar 2015 21:53:21 -0300 Subject: [PATCH] Update detectormorph.cpp New enhancements to better filter out false positives --- src/openalpr/detection/detectormorph.cpp | 128 ++++++++++++++++++----- 1 file changed, 103 insertions(+), 25 deletions(-) diff --git a/src/openalpr/detection/detectormorph.cpp b/src/openalpr/detection/detectormorph.cpp index d6dd178..802a77d 100644 --- a/src/openalpr/detection/detectormorph.cpp +++ b/src/openalpr/detection/detectormorph.cpp @@ -32,10 +32,28 @@ namespace alpr { DetectorMorph::~DetectorMorph() { } + bool DetectorMorph::ValidateCharAspect(Rect& r0, float idealAspect) { + if ((r0.width < 5 || r0.width > 20) + || (r0.height < 15 || r0.height > 40)) return false; + + float aspectChar = ((float)r0.width / (float)r0.height); + + float deltaChar = fabs(idealAspect - aspectChar); + + if (deltaChar < 0.25) + return true; + else + return false; + + } + vector DetectorMorph::detect(Mat frame, std::vector regionsOfInterest) { - Mat frame_gray; + Mat frame_gray,frame_gray_cp; cvtColor(frame, frame_gray, CV_BGR2GRAY); + + frame_gray.copyTo(frame_g2); + blur(frame_gray, frame_gray, Size(5, 5)); vector detectedRegions; for (int i = 0; i < regionsOfInterest.size(); i++) { @@ -57,9 +75,23 @@ namespace alpr { imshow("Threshold Detector", img_threshold); } - Mat circularElement = getStructuringElement(cv::MORPH_ELLIPSE, Size(5, 5)); - morphologyEx(img_threshold, img_open2, CV_MOP_OPEN, circularElement, cv::Point(-1, -1)); - Mat rectElement = getStructuringElement(cv::MORPH_RECT, Size(20, 4)); + Mat diamond(5, 5, CV_8U, cv::Scalar(1)); + + diamond.at(0, 0) = 0; + diamond.at(0, 1) = 0; + diamond.at(1, 0) = 0; + diamond.at(4, 4) = 0; + diamond.at(3, 4) = 0; + diamond.at(4, 3) = 0; + diamond.at(4, 0) = 0; + diamond.at(4, 1) = 0; + diamond.at(3, 0) = 0; + diamond.at(0, 4) = 0; + diamond.at(0, 3) = 0; + diamond.at(1, 4) = 0; + + morphologyEx(img_threshold, img_open2, CV_MOP_OPEN, diamond, cv::Point(-1, -1)); + Mat rectElement = getStructuringElement(cv::MORPH_RECT, Size(13, 4)); morphologyEx(img_open2, img_threshold, CV_MOP_CLOSE, rectElement, cv::Point(-1, -1)); if (config->debugDetector && config->debugShowImages) { @@ -82,36 +114,82 @@ namespace alpr { while (itc != contours.end()) { //Create bounding rect of object RotatedRect mr = minAreaRect(Mat(*itc)); + + if (mr.angle < -45.) { + mr.angle += 90.0; + swap(mr.size.width, mr.size.height); + } + if (!CheckSizes(mr)) itc = contours.erase(itc); else { ++itc; - if (itc == contours.end()) continue; - rects.push_back(mr); + rects.push_back(mr); } } - //Now prunning based on checking all candidate plates for a min/max number of blobs - Mat img_crop, img_crop_b; - vector< vector< Point> > plateBlobs; - for (int i = 0; i < rects.size(); i++) { - RotatedRect PlateRect = rects[i]; - Size rect_size = PlateRect.size; + //Now prunning based on checking all candidate plates for a min/max number of blobsc + Mat img_crop, img_crop_b, img_crop_th, img_crop_th_inv; + vector< vector< Point> > plateBlobs; + vector< vector< Point> > plateBlobsInv; + double thresholds[] = { 10, 40, 80, 120, 160, 200, 240 }; + const int num_thresholds = 7; + int numValidChars = 0; + Mat rotated; + for (int i = 0; i < rects.size(); i++) { + RotatedRect PlateRect = rects[i]; + Size rect_size = PlateRect.size; - //Crop area around candidate plate - getRectSubPix(frame_gray, rect_size, PlateRect.center, img_crop); - //Thresholding - threshold(img_crop, img_crop_b, 0, 255, cv::THRESH_BINARY_INV + cv::THRESH_OTSU); + // get the rotation matrix + Mat M = getRotationMatrix2D(PlateRect.center, PlateRect.angle, 1.0); + // perform the affine transformation + warpAffine(frame_gray_cp, rotated, M, frame_gray_cp.size(), INTER_CUBIC); + //Crop area around candidate plate + getRectSubPix(rotated, rect_size, PlateRect.center, img_crop); - findContours(img_crop_b, - plateBlobs, // a vector of contours - CV_RETR_EXTERNAL, // retrieve the external contours - CV_CHAIN_APPROX_NONE); // all pixels of each contours + if (config->debugDetector && config->debugShowImages) { + imshow("Tilt Correction", img_crop); + waitKey(0); + } - int numBlobs = plateBlobs.size(); + for (int z = 0; z < num_thresholds; z++) + { - //If too much or too little might not be a true plate - if (numBlobs < 3 || numBlobs > 20) continue; + cv::threshold(img_crop, img_crop_th, thresholds[z], 255, cv::THRESH_BINARY); + cv::threshold(img_crop, img_crop_th_inv, thresholds[z], 255, cv::THRESH_BINARY_INV); + + findContours(img_crop_th, + plateBlobs, // a vector of contours + CV_RETR_LIST, // retrieve the contour list + CV_CHAIN_APPROX_NONE); // all pixels of each contours + + findContours(img_crop_th_inv, + plateBlobsInv, // a vector of contours + CV_RETR_LIST, // retrieve the contour list + CV_CHAIN_APPROX_NONE); // all pixels of each contours + + int numBlobs = plateBlobs.size(); + int numBlobsInv = plateBlobsInv.size(); + + float idealAspect = config->charWidthMM / config->charHeightMM; + for (int j = 0; j < numBlobs; j++) { + cv::Rect r0 = cv::boundingRect(cv::Mat(plateBlobs[j])); + + if (ValidateCharAspect(r0, idealAspect)) + numValidChars++; + } + + for (int j = 0; j < numBlobsInv; j++) + { + cv::Rect r0 = cv::boundingRect(cv::Mat(plateBlobsInv[j])); + if (ValidateCharAspect(r0, idealAspect)) + numValidChars++; + } + + } + //If too much or too lcittle might not be a true plate + //if (numBlobs < 3 || numBlobs > 50) continue; + if (numValidChars < 4 || numValidChars > 50) continue; PlateRegion PlateReg; @@ -153,8 +231,8 @@ namespace alpr { if (r < 1) r = (float) mr.size.height / (float) mr.size.width; - if ((area < min || area > max) || (r < rmin || r > rmax) || - (mr.size.width < 20 || mr.size.width > 300)) + if ( (area < min || area > max) || (r < rmin || r > rmax) || + (mr.size.width < 70 || mr.size.width > 300) || (mr.size.height < 10 || mr.size.height > 80) ) return false; else return true;