xphoto inpaint crush

[saedrna]

System information (version)

• OpenCV => 3.2
• Operating System / Platform => Mac OS(installed with homebrew) and Windows(installed with cmake)
• Compiler => clang(mac os) and msvc 2015 (windows)

Detailed description

Sometimes the xphoto::inpaint function will crash with exception Exception: EXC_BAD_ACCESS (code=1, address=0x11ef10ffc) . But not for all the images.

Steps to reproduce

I have upload a project with images below. And here is the code.

#include <iostream>
#include <string>
#include <vector>

#include <opencv2/core.hpp>
#include <opencv2/xphoto.hpp>
#include <opencv2/highgui.hpp>

using namespace std;
using namespace cv;

void inpaint_rgb() {
    string path_mask = "mask1.png";
    string path_gt = "1.png";
    string path_img = path_gt;
    string path_inpaint = "result-1.png";

    Mat gt = cv::imread(path_gt, cv::IMREAD_GRAYSCALE);
    Mat mask = cv::imread(path_mask, cv::IMREAD_GRAYSCALE);
    Mat img = cv::imread(path_img, cv::IMREAD_COLOR);

    img.setTo(cv::Scalar(0,0,0), mask == 255);
    Mat inpainted;
    mask = 255 - mask;
    cv::xphoto::inpaint(img, mask, inpainted, 0);
    cv::imwrite(path_inpaint, inpainted);
}

int main() {
    inpaint_rgb();
    return 0;
}

inpaint.zip

[savuor]

@saedrna this code produces an error very rarely, usually it works with no problem.
Also I failed to reproduce this on Linux.
Will keep trying to catch a problem.

[saedrna]

Yes, really weird. Because previously, when I debug this code, I came into exceptions and the code stop in somewhere in annf.hpp, in Visual Studio 2015. But today, (when I want to show you where is the code) the program runs fine.

Also on Mac, not all the images will produce the exception, when using a inpaint benchmark dataset.

I will keep you informed when I manage to locate an error.

Below is the location of error in XCode, because I do not know how to build opencv_contrib on Mac OS, only something about KDTree is shown here.

[saedrna]

I have successfully build the debug version of opencv_contrib and here is more debug information.

The problem is located in the following function, and the value x itself is bad allocated. Although this is on Mac, I remember the problem is the same for Windows VS 2015.

class KDTreeComparator
    {
        const KDTree <Tp, cn> *main; // main class
        int dimIdx; // dimension to compare

    public:
        bool operator () (const int &x, const int &y) const
        {
            cv::Vec <Tp, cn> u = main->data[main->idx[x]];
            cv::Vec <Tp, cn> v = main->data[main->idx[y]];

            return  u[dimIdx] < v[dimIdx];
        }

        KDTreeComparator(const KDTree <Tp, cn> *_main, int _dimIdx)
            : main(_main), dimIdx(_dimIdx) {}
    };

This functor is used in the nth_element function, idx seems to a growing sequence and here is something not consistent. (left = 0, right = 153601). Because I do not quite understand the algorithm, I can not go any further. Hope this will help.

  std::nth_element(/**/
            idx.begin() +  _left,
            idx.begin() +    nth,
            idx.begin() + _right, comp
                         /**/);

[saedrna]

Here is an dataset that will cause problem.

The problem is another space, where whs is 12 channel but kdtree requires 24, and crash in the constructor.

The code is below. And the dataset is attached.

#include "stdafx.h"
#include <iostream>
#include <string>
#include <vector>

#include <opencv2/core.hpp>
#include <opencv2/xphoto.hpp>
#include <opencv2/highgui.hpp>

using namespace std;
using namespace cv;

int main() {

    string path_mask = "mask.tif";
    string path_image = "img.tif";

    Mat img = cv::imread(path_image, cv::IMREAD_UNCHANGED);
    Mat mask = cv::imread(path_mask, cv::IMREAD_UNCHANGED);

    Mat inpainted;
    xphoto::inpaint(img, mask, inpainted, 0);

    cv::imshow("inpaint", inpainted);
    cv::waitKey();

    return 0;
}

inpaint.zip

[savuor]

@saedrna I confirm the bug, it is reproduced, now investigating it

[kznsq]

Some issues were found in the inpaint code:

1. I've found an issue with the using std::nth_element in the file "xphoto/src/annf.hpp".
   It seems like an inconsistency of sorting data because of using dependent data in main->idx while it is sorting.
   The issue can be fixed with making a copy of sorting data:

line 168:
std::vector<int> _idx(idx.begin(), idx.end());
        std::nth_element(/**/
            _idx.begin() +  _left,
            _idx.begin() +    nth,
            _idx.begin() + _right, comp
                         /**/);
        idx = _idx;

2. Also there is a potential crash in the code if nTransform is greagter than amount.size():

line 283:
    std::partial_sort( amount.begin(), amount.begin() + nTransform,
        amount.end(), std::greater< std::pair<double, int> >() );

My fix:

line 283:
    int num = std::min((int)amount.size(), (int)nTransform);
    std::partial_sort( amount.begin(), amount.begin() + num,
        amount.end(), std::greater< std::pair<float, int> >() );

    transforms.resize(num);
    for (int i = 0; i < num; ++i)
    {
        int idx = amount[i].second;
        transforms[i] = cv::Point2i( shiftM[idx].x, shiftM[idx].y );
    }

[alalek]

@kznsq Feel free to prepare Pull Request (bugfix patches should go into 3.4 branch first)