Bug: Dependencies between detector runs on LBP

[almln]

There is some bug with cv::CascadeClassifier in case of lbpcascade_frontalface:
We have 3 photos (attached files arranged as 02463d131, 02463d139, 02463d142 respectively). Сonsistently run detector on them. For the last picture we get the wrong result. Remove, for example, the second photo. Now, the result for the third picture changed and became correct.
This observation is true only for lbp cascades. On haarcascade all is ok.
See attached files for more info.

Build info:
openCV 3.0.0, vc12, static

Code:

#include <opencv2\opencv.hpp>

int main() {

    std::string f1 = "C:/test/detection/imgs/02463d131.jpg";
    std::string f2 = "C:/test/detection/imgs/02463d139.jpg";
    std::string f3 = "C:/test/detection/imgs/02463d142.jpg";

    cv::Mat im1 = cv::imread(f1, CV_LOAD_IMAGE_GRAYSCALE);
    cv::Mat im2 = cv::imread(f2, CV_LOAD_IMAGE_GRAYSCALE);
    cv::Mat im3 = cv::imread(f3, CV_LOAD_IMAGE_GRAYSCALE);

    cv::CascadeClassifier faceCascade;
    bool isok = faceCascade.load("C:/test/detection/cv_bug/lbpcascade_frontalface.xml");
    //bool isok = faceCascade.load("C:/test/detection/cv_bug/haarcascade_frontalface_alt.xml");

    std::vector<cv::Rect> output1, output2, output3;
    faceCascade.detectMultiScale(im1, output1, 1.16, 1, 0, cv::Size(100, 100), cv::Size(0.99 * im1.cols, 0.99 * im1.cols));
    //faceCascade.detectMultiScale(im2, output2, 1.16, 1, 0, cv::Size(100, 100), cv::Size(0.99 * im2.cols, 0.99 * im2.cols));
    faceCascade.detectMultiScale(im3, output3, 1.16, 1, 0, cv::Size(100, 100), cv::Size(0.99 * im3.cols, 0.99 * im3.cols));

    std::cout << "02463d131.jpg: " << output1[0] << " Face detected: " << output1.size() << '\n';
    //std::cout << "02463d139.jpg: " << output2[0] << " Face detected: " << output2.size() << '\n';
    std::cout << "02463d142.jpg: " << output3[0] << " Face detected: " << output3.size() << '\n';

    std::cin.get();

    return 0;
}

[almln]

This bug is connected with openCL. There is no problem with openCV build without openCL.

[StevenPuttemans]

OpenCL is known to cause issues. Either

• Explicitly disable OpenCL in OpenCV building process
• Or add ocl::setUseOpenCL(false); at the beginning of your code file

Both will make the sample work, just tested here locally.

[leugenea]

Tested again, now on Ubuntu 16.04.01, OpenCV 3.1.0, same issue.

[StevenPuttemans]

@leugenea did you disable OpenCL?

[leugenea]

@StevenPuttemans , yes, without OpenCL everything works just fine. And even on PCs without GPU (Intel or NVidia).

[StevenPuttemans]

BTW just confirmed again with a collegue, this bug is still alive. OpenCL implementation of detectMultiscale completely brakes down the detector, while explicitly disabling OpenCL makes it run just fine!

[sturkmen72]

just a note:
i was tested this issue before and get same result like

i tested now and it works as expected.

( recently i updated display driver : Intel(R) HD Graphics 4000 10.18.10.4653 ) maybe outdated display driver was the reason. or the bug is fixed somehow.