mirror of
https://github.com/kerberos-io/openalpr-base.git
synced 2025-10-06 00:46:49 +08:00
243 lines
7.4 KiB
C++
243 lines
7.4 KiB
C++
/*
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* Copyright (c) 2014 New Designs Unlimited, LLC
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* Opensource Automated License Plate Recognition [http://www.openalpr.com]
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*
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* This file is part of OpenAlpr.
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*
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* OpenAlpr is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License
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* version 3 as published by the Free Software Foundation
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "detectormorph.h"
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using namespace cv;
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using namespace std;
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namespace alpr {
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DetectorMorph::DetectorMorph(Config* config) : Detector(config) {
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this->loaded = true;
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}
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DetectorMorph::~DetectorMorph() {
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}
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bool DetectorMorph::ValidateCharAspect(Rect& r0, float idealAspect) {
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if ((r0.width < 5 || r0.width > 20)
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|| (r0.height < 15 || r0.height > 40)) return false;
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float aspectChar = ((float)r0.width / (float)r0.height);
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float deltaChar = fabs(idealAspect - aspectChar);
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if (deltaChar < 0.25)
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return true;
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else
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return false;
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}
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vector<PlateRegion> DetectorMorph::detect(Mat frame, std::vector<cv::Rect> regionsOfInterest) {
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Mat frame_gray,frame_gray_cp;
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cvtColor(frame, frame_gray, CV_BGR2GRAY);
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frame_gray.copyTo(frame_gray_cp);
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blur(frame_gray, frame_gray, Size(5, 5));
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vector<PlateRegion> detectedRegions;
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for (int i = 0; i < regionsOfInterest.size(); i++) {
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Mat img_open, img_result;
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Mat element = getStructuringElement(MORPH_RECT, Size(30, 4));
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morphologyEx(frame_gray, img_open, CV_MOP_OPEN, element, cv::Point(-1, -1));
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img_result = frame_gray - img_open;
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if (config->debugDetector && config->debugShowImages) {
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imshow("Opening", img_result);
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}
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//threshold image using otsu thresholding
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Mat img_threshold, img_open2;
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threshold(img_result, img_threshold, 0, 255, CV_THRESH_OTSU + CV_THRESH_BINARY);
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if (config->debugDetector && config->debugShowImages) {
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imshow("Threshold Detector", img_threshold);
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}
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Mat diamond(5, 5, CV_8U, cv::Scalar(1));
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diamond.at<uchar>(0, 0) = 0;
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diamond.at<uchar>(0, 1) = 0;
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diamond.at<uchar>(1, 0) = 0;
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diamond.at<uchar>(4, 4) = 0;
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diamond.at<uchar>(3, 4) = 0;
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diamond.at<uchar>(4, 3) = 0;
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diamond.at<uchar>(4, 0) = 0;
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diamond.at<uchar>(4, 1) = 0;
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diamond.at<uchar>(3, 0) = 0;
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diamond.at<uchar>(0, 4) = 0;
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diamond.at<uchar>(0, 3) = 0;
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diamond.at<uchar>(1, 4) = 0;
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morphologyEx(img_threshold, img_open2, CV_MOP_OPEN, diamond, cv::Point(-1, -1));
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Mat rectElement = getStructuringElement(cv::MORPH_RECT, Size(13, 4));
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morphologyEx(img_open2, img_threshold, CV_MOP_CLOSE, rectElement, cv::Point(-1, -1));
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if (config->debugDetector && config->debugShowImages) {
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imshow("Close", img_threshold);
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waitKey(0);
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}
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//Find contours of possibles plates
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vector< vector< Point> > contours;
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findContours(img_threshold,
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contours, // a vector of contours
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CV_RETR_EXTERNAL, // retrieve the external contours
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CV_CHAIN_APPROX_NONE); // all pixels of each contours
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//Start to iterate to each contour founded
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vector<vector<Point> >::iterator itc = contours.begin();
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vector<RotatedRect> rects;
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//Remove patch that are no inside limits of aspect ratio and area.
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while (itc != contours.end()) {
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//Create bounding rect of object
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RotatedRect mr = minAreaRect(Mat(*itc));
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if (mr.angle < -45.) {
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mr.angle += 90.0;
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swap(mr.size.width, mr.size.height);
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}
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if (!CheckSizes(mr))
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itc = contours.erase(itc);
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else {
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++itc;
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rects.push_back(mr);
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}
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}
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//Now prunning based on checking all candidate plates for a min/max number of blobsc
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Mat img_crop, img_crop_b, img_crop_th, img_crop_th_inv;
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vector< vector< Point> > plateBlobs;
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vector< vector< Point> > plateBlobsInv;
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double thresholds[] = { 10, 40, 80, 120, 160, 200, 240 };
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const int num_thresholds = 7;
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int numValidChars = 0;
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Mat rotated;
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for (int i = 0; i < rects.size(); i++) {
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numValidChars = 0;
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RotatedRect PlateRect = rects[i];
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Size rect_size = PlateRect.size;
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// get the rotation matrix
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Mat M = getRotationMatrix2D(PlateRect.center, PlateRect.angle, 1.0);
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// perform the affine transformation
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warpAffine(frame_gray_cp, rotated, M, frame_gray_cp.size(), INTER_CUBIC);
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//Crop area around candidate plate
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getRectSubPix(rotated, rect_size, PlateRect.center, img_crop);
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if (config->debugDetector && config->debugShowImages) {
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imshow("Tilt Correction", img_crop);
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waitKey(0);
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}
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for (int z = 0; z < num_thresholds; z++) {
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cv::threshold(img_crop, img_crop_th, thresholds[z], 255, cv::THRESH_BINARY);
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cv::threshold(img_crop, img_crop_th_inv, thresholds[z], 255, cv::THRESH_BINARY_INV);
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findContours(img_crop_th,
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plateBlobs, // a vector of contours
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CV_RETR_LIST, // retrieve the contour list
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CV_CHAIN_APPROX_NONE); // all pixels of each contours
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findContours(img_crop_th_inv,
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plateBlobsInv, // a vector of contours
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CV_RETR_LIST, // retrieve the contour list
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CV_CHAIN_APPROX_NONE); // all pixels of each contours
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int numBlobs = plateBlobs.size();
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int numBlobsInv = plateBlobsInv.size();
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float idealAspect = config->charWidthMM / config->charHeightMM;
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for (int j = 0; j < numBlobs; j++) {
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cv::Rect r0 = cv::boundingRect(cv::Mat(plateBlobs[j]));
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if (ValidateCharAspect(r0, idealAspect))
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numValidChars++;
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}
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for (int j = 0; j < numBlobsInv; j++) {
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cv::Rect r0 = cv::boundingRect(cv::Mat(plateBlobsInv[j]));
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if (ValidateCharAspect(r0, idealAspect))
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numValidChars++;
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}
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}
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//If too much or too lcittle might not be a true plate
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//if (numBlobs < 3 || numBlobs > 50) continue;
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if (numValidChars < 4 || numValidChars > 50) continue;
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PlateRegion PlateReg;
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PlateReg.rect = PlateRect.boundingRect();
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if (PlateReg.rect.x < 0)
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PlateReg.rect.x = 0;
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if (PlateReg.rect.y < 0)
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PlateReg.rect.y = 0;
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if (PlateReg.rect.x + PlateReg.rect.width > frame.cols)
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PlateReg.rect.width = frame.cols - PlateReg.rect.x;
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if (PlateReg.rect.y + PlateReg.rect.height > frame.rows)
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PlateReg.rect.height = frame.rows - PlateReg.rect.y;
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detectedRegions.push_back(PlateReg);
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}
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}
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return detectedRegions;
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}
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bool DetectorMorph::CheckSizes(RotatedRect& mr) {
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float error = 1.2;
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float aspect = config->plateWidthMM / config->plateHeightMM;
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//Set a min and max area. All other patchs are discarded
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int min = 10 * aspect * 10; // minimum area
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int max = 100 * aspect * 100; // maximum area
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//Get only patchs that match to a respect ratio.
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float rmin = 3.0;
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float rmax = 7.0;
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int area = mr.size.height * mr.size.width;
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float r = (float) mr.size.width / (float) mr.size.height;
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if (r < 1)
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r = (float) mr.size.height / (float) mr.size.width;
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if ( (area < min || area > max) || (r < rmin || r > rmax) ||
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(mr.size.width < 70 || mr.size.width > 300) || (mr.size.height < 10 || mr.size.height > 80) )
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return false;
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else
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return true;
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}
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}
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