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/*M///////////////////////////////////////////////////////////////////////////////////////
//
// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
//
// By downloading, copying, installing or using the software you agree to this license.
// If you do not agree to this license, do not download, install,
// copy or use the software.
//
//
// Intel License Agreement
// For Open Source Computer Vision Library
//
// Copyright (C) 2000, Intel Corporation, all rights reserved.
// Third party copyrights are property of their respective owners.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// * Redistribution's of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistribution's in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * The name of Intel Corporation may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// This software is provided by the copyright holders and contributors "as is" and
// any express or implied warranties, including, but not limited to, the implied
// warranties of merchantability and fitness for a particular purpose are disclaimed.
// In no event shall the Intel Corporation or contributors be liable for any direct,
// indirect, incidental, special, exemplary, or consequential damages
// (including, but not limited to, procurement of substitute goods or services;
// loss of use, data, or profits; or business interruption) however caused
// and on any theory of liability, whether in contract, strict liability,
// or tort (including negligence or otherwise) arising in any way out of
// the use of this software, even if advised of the possibility of such damage.
//
//M*/
#include "precomp.hpp"
#include "opencv2/imgproc/imgproc_c.h"
#include "opencv2/calib3d/calib3d_c.h"
#include <vector>
#include <algorithm>
using namespace cv;
using namespace std;
static void icvGetQuadrangleHypotheses(const std::vector<std::vector< cv::Point > > & contours, const std::vector< cv::Vec4i > & hierarchy, std::vector<std::pair<float, int> >& quads, int class_id)
{
const float min_aspect_ratio = 0.3f;
const float max_aspect_ratio = 3.0f;
const float min_box_size = 10.0f;
typedef std::vector< std::vector< cv::Point > >::const_iterator iter_t;
iter_t i;
for (i = contours.begin(); i != contours.end(); ++i)
{
const iter_t::difference_type idx = i - contours.begin();
if (hierarchy.at(idx)[3] != -1)
continue; // skip holes
const std::vector< cv::Point > & c = *i;
cv::RotatedRect box = cv::minAreaRect(c);
float box_size = MAX(box.size.width, box.size.height);
if(box_size < min_box_size)
{
continue;
}
float aspect_ratio = box.size.width/MAX(box.size.height, 1);
if(aspect_ratio < min_aspect_ratio || aspect_ratio > max_aspect_ratio)
{
continue;
}
quads.push_back(std::pair<float, int>(box_size, class_id));
}
}
static void countClasses(const std::vector<std::pair<float, int> >& pairs, size_t idx1, size_t idx2, std::vector<int>& counts)
{
counts.assign(2, 0);
for(size_t i = idx1; i != idx2; i++)
{
counts[pairs[i].second]++;
}
}
inline bool less_pred(const std::pair<float, int>& p1, const std::pair<float, int>& p2)
{
return p1.first < p2.first;
}
static void fillQuads(Mat & white, Mat & black, double white_thresh, double black_thresh, vector<pair<float, int> > & quads)
{
Mat thresh;
{
vector< vector<Point> > contours;
vector< Vec4i > hierarchy;
threshold(white, thresh, white_thresh, 255, THRESH_BINARY);
findContours(thresh, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE);
icvGetQuadrangleHypotheses(contours, hierarchy, quads, 1);
}
{
vector< vector<Point> > contours;
vector< Vec4i > hierarchy;
threshold(black, thresh, black_thresh, 255, THRESH_BINARY_INV);
findContours(thresh, contours, hierarchy, RETR_CCOMP, CHAIN_APPROX_SIMPLE);
icvGetQuadrangleHypotheses(contours, hierarchy, quads, 0);
}
}
static bool checkQuads(vector<pair<float, int> > & quads, const cv::Size & size)
{
const size_t min_quads_count = size.width*size.height/2;
std::sort(quads.begin(), quads.end(), less_pred);
// now check if there are many hypotheses with similar sizes
// do this by floodfill-style algorithm
const float size_rel_dev = 0.4f;
for(size_t i = 0; i < quads.size(); i++)
{
size_t j = i + 1;
for(; j < quads.size(); j++)
{
if(quads[j].first/quads[i].first > 1.0f + size_rel_dev)
{
break;
}
}
if(j + 1 > min_quads_count + i)
{
// check the number of black and white squares
std::vector<int> counts;
countClasses(quads, i, j, counts);
const int black_count = cvRound(ceil(size.width/2.0)*ceil(size.height/2.0));
const int white_count = cvRound(floor(size.width/2.0)*floor(size.height/2.0));
if(counts[0] < black_count*0.75 ||
counts[1] < white_count*0.75)
{
continue;
}
return true;
}
}
return false;
}
// does a fast check if a chessboard is in the input image. This is a workaround to
// a problem of cvFindChessboardCorners being slow on images with no chessboard
// - src: input image
// - size: chessboard size
// Returns 1 if a chessboard can be in this image and findChessboardCorners should be called,
// 0 if there is no chessboard, -1 in case of error
int cvCheckChessboard(IplImage* src, CvSize size)
{
cv::Mat img = cv::cvarrToMat(src);
return checkChessboard(img, size);
}
int checkChessboard(const cv::Mat & img, const cv::Size & size)
{
CV_Assert(img.channels() == 1 && img.depth() == CV_8U);
const int erosion_count = 1;
const float black_level = 20.f;
const float white_level = 130.f;
const float black_white_gap = 70.f;
Mat white;
Mat black;
erode(img, white, Mat(), Point(-1, -1), erosion_count);
dilate(img, black, Mat(), Point(-1, -1), erosion_count);
int result = 0;
for(float thresh_level = black_level; thresh_level < white_level && !result; thresh_level += 20.0f)
{
vector<pair<float, int> > quads;
fillQuads(white, black, thresh_level + black_white_gap, thresh_level, quads);
if (checkQuads(quads, size))
result = 1;
}
return result;
}
// does a fast check if a chessboard is in the input image. This is a workaround to
// a problem of cvFindChessboardCorners being slow on images with no chessboard
// - src: input binary image
// - size: chessboard size
// Returns 1 if a chessboard can be in this image and findChessboardCorners should be called,
// 0 if there is no chessboard, -1 in case of error
int checkChessboardBinary(const cv::Mat & img, const cv::Size & size)
{
CV_Assert(img.channels() == 1 && img.depth() == CV_8U);
Mat white = img.clone();
Mat black = img.clone();
int result = 0;
for ( int erosion_count = 0; erosion_count <= 3; erosion_count++ )
{
if ( 1 == result )
break;
if ( 0 != erosion_count ) // first iteration keeps original images
{
erode(white, white, Mat(), Point(-1, -1), 1);
dilate(black, black, Mat(), Point(-1, -1), 1);
}
vector<pair<float, int> > quads;
fillQuads(white, black, 128, 128, quads);
if (checkQuads(quads, size))
result = 1;
}
return result;
}