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Update detectormorph.cpp

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New enhancements to better filter out false positives
This commit is contained in:
Frederico Lopes
2015-03-18 21:53:21 -03:00
parent 838997925a
commit db4ee4889f
1 changed files with 103 additions and 25 deletions
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128
src/openalpr/detection/detectormorph.cpp
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@@ -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<PlateRegion> DetectorMorph::detect(Mat frame, std::vector<cv::Rect> 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<PlateRegion> 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<uchar>(0, 0) = 0;
diamond.at<uchar>(0, 1) = 0;
diamond.at<uchar>(1, 0) = 0;
diamond.at<uchar>(4, 4) = 0;
diamond.at<uchar>(3, 4) = 0;
diamond.at<uchar>(4, 3) = 0;
diamond.at<uchar>(4, 0) = 0;
diamond.at<uchar>(4, 1) = 0;
diamond.at<uchar>(3, 0) = 0;
diamond.at<uchar>(0, 4) = 0;
diamond.at<uchar>(0, 3) = 0;
diamond.at<uchar>(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;