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2016-07-06 07:30:52 -0500 answered a question When I use 'cvtColor' with JNI, Console says: Fatal signal 11 (SIGSEGV), code 1, fault addr 0xa4400000 in tid 3689

The obtained grayscale image is of type CV_8UC1, so use Byte instead of Int infix in function names (e.g. NewByteArray, ...), or convert grayscale to BGRA once again and use it instead.

2015-11-08 13:59:21 -0500 received badge  Nice Answer (source)
2015-07-16 02:48:45 -0500 answered a question How to remove shadow of image with help of open cv.?

Shadow removal issue usually can be divided on two subtasks:

  1. Shadow localization.
  2. Adjusting colors in shadowed regions.

Although there are a lot of papers on this topic, you can make a solution prototype with a few OpenCV functions:

  1. Try to localize shadow area with threshold.
  2. Solve a system of linear equations with cv::solve() to restore pixel's color in shadowed regions, like color_of_pixel_outside_shadow = x * color_of_pixel_inside_shadow, so 'x' will be a coefficient to restore original color. Also you can try to use cv::inpaint() for shadowed regions.
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2015-03-18 09:56:06 -0500 answered a question Offset calculation for a Mat object (traincascade)

This is due to cv::integral(). It creates output of (rows + 1, cols + 1) size (adds extra 0 row and column), so the stride between rows of integral sum images grows to width + 1.

2015-03-10 14:55:13 -0500 received badge  Nice Answer (source)
2015-02-19 09:05:49 -0500 commented question what is the fastest way to do patch-based image analysis

Try using integral for fast mean, stddev calculation.

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2014-11-12 08:00:18 -0500 commented answer opencv2/core/ultility.hpp not found

Guys, this file exists only in master (OpenCV 3.0), so, please use it.

2014-10-28 03:16:56 -0500 commented answer Computer vision live coding application

Hi Dinu, very nice stuff! Guys form microsoft provided extension for the VS (Image Watch), so you can try to cooperate with them.

2014-09-22 08:40:33 -0500 commented question Vision Challenge is unnoticed

Guys, wiki page is a bit outdated. Whole team is working, probably update will be at the EOW (contest hasn't started yet).

2014-09-19 03:30:02 -0500 commented answer How to use parallel_for?
2014-09-02 05:58:17 -0500 answered a question Is it Possible to Create a Continuous Image?

Hi Adi,

Allocation is done in Mat::create function, it's aligned, but continuous memory strip.

2014-09-01 01:55:35 -0500 commented answer OpenCV Java camera calibration

The key of object points is their relative position, so in case of regular chessboard they can be set as described in tutorial. To undistort picture this would be sufficient. But, if you want to use intrinsic parameters beyond in the code, where real word objects sizes are matters, you should involve square size of chessboard in object points calculations. Check the samples, they both use it.

2014-08-31 14:00:51 -0500 answered a question OpenCV Java camera calibration


You should add object points for each found corners entry and perform calibration after gathering sufficient number of corners (try all default chess*.png images). Also you've mixed x and y in Point3 constructor. Check the full pipeline in Android (asymmetric circles grid pattern is used) or c++ sample.

2014-08-28 08:11:49 -0500 commented answer Android not found

But the error message tells, that library isn't found, so figure out are there any problems with loading. You can try to load opencv with dlopen right before loading enzo and check the error message from dlerror. Don't forget, you should load opencv before enzo.

2014-08-26 05:37:05 -0500 commented answer Android not found

You've just set the dependency. Now load it (with System.loadLibray(...) in java or dlopen(...) in c++).

2014-08-26 03:30:46 -0500 answered a question Android not found

Your is depended from OpenCV. So make sure, you've loaded before. You can download it from sourceforge.

2014-06-25 09:28:01 -0500 commented question Meanshift clustering
2014-05-21 09:56:43 -0500 commented question How to display text on the windows (webcam windows) openCV?

Mat::zeros(imgH,imgW,CV_WINDOW_AUTOSIZE) -> Mat::zeros(imgH,imgW,CV_8UC1)

2014-05-21 09:53:29 -0500 commented question Parallel remap

Yes, it will.

2014-04-10 04:38:37 -0500 commented question Opencv with native android

Have you checked face-detection sample: It has jni part.

2014-03-31 14:30:57 -0500 commented answer How to pass a MatOfKeyPoint and MatOfPoint2f to native code? (OpenCV 4 Android)

Nice to see you here!

2014-03-31 03:48:43 -0500 answered a question How to pass a MatOfKeyPoint and MatOfPoint2f to native code? (OpenCV 4 Android)

Hi! MatOfKeyPoint just extends Mat (you can check implemetation in src/org/opencv/core/ of your OpenCV android sdk). So, in native side, it just a Mat with CV_32FC7 type. Try to cast it to Mat in usual way.

2014-03-27 02:44:05 -0500 commented answer Unusual behavior of Matx

@Moster By default in Fortran arrays are started from 1 (but you can specify other indexation order:

2014-03-25 10:43:15 -0500 answered a question Would you be willing to share your buildbot config?

There are some ways to do this:

  1. Set up a webhook for PullRequestEvent. It sends POST request to your server with essential information about PR, so you can run builder(s) if request is received - Proper way.
  2. Take a look on GitHub API. It allows you receive information about each pull requests by demand (e.g. curl
    So, you can periodically examine PR's statuses, and if they have been recently updated (field updated_at in response) run the builders - Tricky, but fast to implement solution.
2014-03-24 05:31:07 -0500 commented answer Detect and remove borders from framed photographs

@Mostafa Sataki Thanks for cool answer!

2014-03-13 01:36:46 -0500 commented answer Alternatives for SIFT, ORB and FAST

Without filtering it's usually hard to achive good results with FAST, GFTT detector's. For ratio test check this (it's in python, but you can catch the idea).

2014-03-12 02:59:56 -0500 commented question Equivalent code in Java replacing pixels
2014-03-12 02:57:11 -0500 commented question Type of Matrix of a depth Image

Looks like you've found a bug, sample code uses short. Please, send a pull request with fix. It will help a lot!

2014-03-12 02:49:57 -0500 commented answer Alternatives for SIFT, ORB and FAST

@pats Did you filter your matches? If not, it might be a lot of outliers. For example you can check knnMatch output: if it finds more than one correspondence, you can compare distance ratio between these correspondences and, if it's bigger than some threshold, it will be an outlier. This should help. Also there is a lot of keypoints on shirt - this can be due to low detector's thresholds. Tune them or try GFTTDetector, which has a lot of parameters to tune.

2014-03-04 00:26:47 -0500 commented answer Contributing to Feature #3073: Convenient way of initializing RotatedRect

Thanks for PR!

2014-02-24 03:47:09 -0500 commented question draw matched features in same image

You can do it manually with line and circle functions. Check the source code of drawMatches for reference.

2014-01-16 08:44:33 -0500 commented question svm train method segmantation fault problem

@hsrt What is your trainingData? Looks like the problem is there.

2014-01-13 08:31:58 -0500 commented question OpenCV compile under WinCE 6.0

Try to build OpenCV from sources. First of all try to build Highgui module for WinCE 6.0. Likely there will be a plenty of errors, but you can skip this module (or it parts). Core and other modules should be built with less troubles.

2014-01-13 08:24:02 -0500 commented question Add constant to each element of ListOfPoints
2014-01-13 08:18:37 -0500 answered a question Android: Problem passing BGRA Mat to JNI function with C++ background

Hi, as logcat says, your code have some unimplemented under Android methods, like imshow or namedWindow. Suggest you to check Java API docs.

2014-01-13 08:08:40 -0500 commented question Looking for samples to help port C++ OpenCV project to Android

First of all use in your main OpenCV C++ API. After that take a look at Android OpenCV samples: They covers the most common usecases. I suggest to start work with camera (since Highgui module is currently absent on android), the thinnest example is

2014-01-13 07:51:23 -0500 commented question how to set environment variable path on ubuntu 12.04 lts for OpenCV

Looks like you need "/home/kaushal/OpenCV/opencv-2.4.7/modules/highgui/include/opencv2/highgui.hpp"

2013-12-13 23:17:36 -0500 answered a question i have problems with handling mouse event in opencv

Hi Amin, you should show modyfied image after draw a circle, so

    circle( image, Point(x,y), 20, Scalar(0xff,0xff,0xff) );
    imshow("amin", image);

should help.

2013-12-10 06:47:03 -0500 commented answer OpenCv for Android: camera not working on motorolla.

Please, post logcat output.

2013-12-03 04:13:26 -0500 commented answer how can I align Face Images