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2020-08-04 06:15:34 -0500 commented question Memory leak in RGB2Lab

I've added the valgrind output with debug info enabled, this shows a function initLabTabs() in color_lab.cpp this functi

2020-08-04 04:03:50 -0500 edited question Memory leak in RGB2Lab

Memory leak in RGB2Lab There is a memory leak when using RBG2Lab. Is this an issue with OpenCV? The version is 3.4.11.

2020-08-03 10:05:48 -0500 commented question Memory leak in RGB2Lab

The OS is CentOS 6.10. It is not progressive. cv::getBuildInformation() output added to the question.

2020-08-03 10:04:58 -0500 edited question Memory leak in RGB2Lab

Memory leak in RGB2Lab There is a memory leak when using RBG2Lab. Is this an issue with OpenCV? The version is 3.4.11.

2020-08-03 10:03:15 -0500 commented question Memory leak in RGB2Lab

The OS is CentOS 6.10. It is not progressive.

2020-08-03 04:51:12 -0500 edited question Memory leak in RGB2Lab

Memory leak in RGB2Lab There is a memory leak when using RBG2Lab. Is this an issue with OpenCV? The version is 3.4.11.

2020-08-03 04:49:44 -0500 asked a question Memory leak in RGB2Lab

Memory leak in RGB2Lab There is a memory leak when using RBG2Lab. Is this an issue with OpenCV? The version is 3.4.11.

2019-11-25 16:11:44 -0500 received badge  Popular Question (source)
2017-04-21 10:19:33 -0500 commented question Changes in version 3.0.0 to 3.1.0 or 3.2.0 in Core.add()

this answer suggests to use addWeighted

2017-03-14 09:19:18 -0500 commented question Floating point exception when looping and reading images

Why not pass the image (as an argument) to the c++ program that you call from the script?

2017-01-06 08:19:04 -0500 asked a question How to calculate text dimensions for anti-aliased linetype?

I know how to obtain the dimensions of the text using cv::getTextSize(), but this only works correctly for non-antialiased linetypes (default=8 and 4).

When using CV_AA (linetype=16) the text is partially outside the size defined by cv::getTextSize().

Edit: Should I file an issue for this on GitHub? For now I've decided to not use a anti-aliased linetype.

2016-10-26 07:25:54 -0500 commented question [Stitching_detailed.cpp] Matcher as cv::Ptr discussion thread.

cv::Ptr is not just a 'normal' pointer. It is a smart pointer and you cannot treat it as a normal pointer. It also has some advantages over a normal pointer. Read the docs for that: cv::Ptr

2016-08-24 01:09:05 -0500 received badge  Nice Answer (source)
2016-06-14 04:22:33 -0500 commented question extract only data with open cv?

full video link to save you the trouble of registering

2016-06-13 06:28:58 -0500 commented question How can I translate Matlab code to opencv to align image?

I don't mean to be rude, but you really should try to ask better questions, show some effort! We - just like you - don't like to waste valuable time.

2016-06-03 07:32:53 -0500 commented answer abi checks

Please guarantee binary-level compatibility between major versions. This I think is the best way to avoid dependency 'hell' and most clear to developers and users, especially from a linux background. Semantic Versioning. As a side-note; I personally like the way Intel IPP deprecates functionality and notifies users (link). They mark many things they believe should be deprecated as such and users are encouraged to report if a deprecation of a particular feature will cause problems for them.

2016-04-28 02:56:05 -0500 commented question How to recast mat as const

Is const_cast what you're looking for?

2016-04-25 03:22:15 -0500 commented question double free or corruption (!prev) c++ opencv

don't new the return Mat in both places (inside decompose function and where you call it), Btw there is really no need to use new anyway.

2016-02-23 06:48:27 -0500 answered a question Naming OpenCV target DLLs, when building from source on Windows

Versioning is added here. So you can modify the cmake file there to not add the version to the filename.

The question you should ask yourself is why you want to link to unversioned libraries.

If you have just one application or library that also distributes the opencv DLL's it isn't that important. But when you start to have multiple applications or libraries (that are all linked to an unversioned DLL) you would have to recompile them all when you want to upgrade opencv. With versioned DLL's library A could be linked against opencv_core2410.dll and application B can be linked agains opencv_core300.dll and both DLL's can be distributed to the client without interfering.

Therefore, it is advisable to use versions.

2016-01-15 06:49:15 -0500 commented question I am a new in programming and opencv as well, I would like to learn it in a perfect way possible. how can I read a video from a file? is there any requirement to do so?

Tip: start simple, with still images for example instead of video. If you need more help, explain what you want to achieve.

2016-01-15 06:44:50 -0500 commented question How to compare compare contour of two image

area[i+1] is simply wrong. What have you already tried so far? You seem to have good understanding of what you want to do.

2016-01-11 03:36:20 -0500 commented question Why doesn't the inRange() function detect this little red colored blob in this 50px Mat?

What is the hsv value of the color according to opencv? Is it what you expect? Also, avoid posting/using compressed image formats (jpg) for accurate color detection/conversion stuff.

2015-12-17 10:29:14 -0500 commented question Trouble to compile opencv 3.0.0 solution (.sln) file with visual studio when the BUILD_OPENCV_WORLD is included in cmake (3.4.1)

Post your CMake output please.

2015-12-17 02:45:37 -0500 commented answer Error Building OpenCV from Source

maybe related to: this?

2015-12-16 08:10:59 -0500 edited question with python2.7 and 3.4

Hi, I built for python2.7 and python3.4 in raspbian. They both work and I can do import cv2.

However, when I wanted to understand where all the binaries are installed by cmake, I noticed something strange and I didn't understand.

Both py2.7 and py3.4 files are depending on the same shared objects. The following is the ldd output

    $ldd  #python 2.7 (0x7ee2d000)
    /usr/lib/arm-linux-gnueabihf/ (0x76e66000)
    ** => /usr/lib/arm-linux-gnueabihf/ (0x76b2f000)        ** => /lib/ (0x7691c000) => /lib/ (0x768c9000) => /lib/ (0x765f8000) => /lib/ (0x76561000)

    $ldd #python 3.4     (0x7ef97000)
    /usr/lib/arm-linux-gnueabihf/ (0x76dce000)
    ** => /usr/lib/arm-linux-gnueabihf/ (0x769fe000)        ** => /lib/ (0x767eb000) => /lib/ (0x76798000) => /lib/ (0x764c7000) => /lib/ (0x76430000)

Do note the offsets in brackets seem to differ between the two versions. Otherwise both py2.7 and py34 are dependent on the shared objects ( etc).

Is this correct or is something wrong and it may cause problems later. If this right, could you please tell me how this works and why mixing so files is ok here?
Thanks T

2015-12-15 05:15:49 -0500 commented question Error Building OpenCV from Source

What if you choose 'Reload All'?. Did you notice that it isn't actually using IPP 9? Check the cmake output. Also it looks like it is trying to build after the cmake has run (see bottom of 'OpenCV Build Output.txt'). Have you tried to start over with a clean build/ directory and re-run cmake?

2015-12-15 04:42:47 -0500 commented question Build Opencv2.4.11 from source on RHEL 6.6

What does your cmake output look like?

2015-12-11 04:43:18 -0500 commented answer Errors in directx.hpp 3.0 Dev

I don't understand what you don't understand;). Without this control there would be multiple declaration's of the struct. That does not necessarily hurt, but this way you give the header the full responsibility to declare (and define) the struct. In my opinion this is just another case of enabling 'things', in this case it is the not needing to declare a struct again... nothing special going on.

2015-12-11 03:40:36 -0500 commented question Memory leak in Mat::convertTo

Can you explain how this is going to leak? Or how you analysed and concluded the leak?

2015-12-11 03:21:31 -0500 commented answer Errors in directx.hpp 3.0 Dev

But that 'someone' is going to be the header that defines that struct ID3D11Device, it should never be defined by your own code. This is merely a interface class it doesn't know anything about the types. That is why it only declares it, but does not define it difference. It trusts the header that has __d3d11_h__ defined to also declare the struct ID3D11Device. You also might want to google this to see how that works.

2015-12-10 08:20:43 -0500 commented question [Help] Error imwrite opencv 3.0 and VS 2012

Code and possibly image please, no screenshots, thank you

2015-12-10 08:09:53 -0500 answered a question Errors in directx.hpp 3.0 Dev

No, it shouldn't.

It does not include the structures, only declares it. And it probably does it this way so it can compile even if no DirectX header is available.

2015-12-10 08:07:59 -0500 edited question Errors in directx.hpp 3.0 Dev

In the header there are 3 tests for __d3d11_h__ and 10 and 9 versions, but the tests only include the structures if these are NOT defined!

#if !defined(__d3d11_h__)
struct ID3D11Device;

Shouldn't the negate be removed, so:-

#if defined(__d3d11_h__)
struct ID3D11Device;
2015-12-10 07:30:43 -0500 edited question CMakeList for Gphoto2 and OpenCV

For building the attached cpp file I receive CMAKE_MODULE_PATH error while running make command on Terminal.

It uses Gphoto2 and OpenCV to capture live images from a digital camera. This files is based on

I believe the problem is caused by a wrong CMakeLists.txt file, however I do not know how to fix it. Thanks for your guidance in advance.

grayp.cpp file:

#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <opencv2/structured_light.hpp>
#include <iostream>
#include <stdio.h>
using namespace cv;
using namespace std;
int main( )

// Open camera,  using libgphoto2
VideoCapture cap1( CAP_GPHOTO2 );

if( !cap1.isOpened() )
// check if cam1 opened
cout << "cam1 not opened!" << endl;}
cout <<"FFFFFFFFFFFFFFFF"<< endl;

 // the camera will be deinitialized automatically in VideoCapture destructor
cout << "Closing program" << endl;
return 0;

CMakeLists.txt file:

cmake_minimum_required(VERSION 2.8)
project( grayp )
find_package( OpenCV REQUIRED )
add_executable( grayp grayp.cpp )
target_link_libraries( grayp ${OpenCV_LIBS} )
option(GPHOTO2 "test" ON)
find_package( GPHOTO2 REQUIRED )
set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} "${CMAKE_SOURCE_DIR}/home/pi/code/prof/gray")
2015-11-25 09:15:30 -0500 commented question OpenCV stops working well.

What exactly do you mean with 'does not work'? How did you reinstalled opencv?

2015-11-05 07:34:54 -0500 answered a question What is the complimentary operation of cvConvertScale for Mat?
2015-11-05 07:31:26 -0500 commented question coversion of image from uchar to float

besides.. malloc() is not what you should use if your doing c++. And if you encounter problems 'when i do some image processing' its better to describe what the 'problems' and 'some image processing' are. Now we have no idea!

2015-11-03 07:30:23 -0500 commented question VideoCapture won't open camera on osx

I remember having to put this for my Macbooks iSight camera to open properly, don't ask me how I figured this out..

// set video capture properties for MacBook' iSight camera
videoCapture.set(CV_CAP_PROP_FRAME_WIDTH, 500);
videoCapture.set(CV_CAP_PROP_FRAME_HEIGHT, 600);
2015-11-02 04:40:28 -0500 commented question Copy cropped image

So you are only modifying m_croppedRenderImg->data? What about it's dimensions? I don't know your reasons to do so much pointer fiddling, you know about OpenCV's memory management already being quite efficient right?

2015-10-23 07:44:57 -0500 received badge  Scholar (source)
2015-10-23 07:44:55 -0500 commented answer canny apertureSize parameter doesn't work

thank you @berak. Python beginner here.., thanks for explaining

2015-10-23 05:27:30 -0500 asked a question canny apertureSize parameter doesn't work

The apertureSize parameter as described by the canny documentation does not give any difference in the detected edges.

Here is my code:

thresh1 = 100
thresh2 = 200
aperture1 = 3
aperture2 = 7
img = cv2.imread("lena.png", 0)
edges1 = cv2.Canny(img, thresh1, thresh2, aperture1)
edges2 = cv2.Canny(img, thresh1, thresh2, aperture2)
cv2.imshow("result aperture 3", edges1)
cv2.imshow("result aperture 7", edges2)

Why are both result images identical?