Comments on: Qt & OpenCV combined for face detecting QWidgets

By: Bluesman

Bluesman — Mon, 21 Feb 2011 03:40:26 +0000

Nice job, very helpful! Quick question:

Couldn’t the the following lines:

if( frame->origin == IPL_ORIGIN_TL )
cvCopy( frame, m_opencvimg, 0 );
else
cvFlip( frame, m_opencvimg, 0 );

cvCvtColor(m_opencvimg, m_opencvimg, CV_BGR2RGB);

Be replaced by:

if( frame->origin == IPL_ORIGIN_TL )
cvCvtColor( frame, m_opencvimg, CV_BGR2RGB);
else
{
cvFlip( frame, m_opencvimg, 0 );
cvCvtColor(m_opencvimg,m_opencvimg,CV_BGR2RGB);
}

to avoid a copy operation in the most common case when a flip is not required? I’ve tried it and it seems to work.

By: Roy

Roy — Thu, 29 Jul 2010 23:17:12 +0000

@Johnson: Sadly, I don’t have the original sources for this project anymore… It must be reconstructed from the sources in the post itself. Sorry.

By: Johnson

Johnson — Thu, 29 Jul 2010 09:14:15 +0000

Hello Roy,

I am a beginner in QT, and I like this example a lot.
Can you send me the whole project of this program?
Thanks in advance.

By: irawan

irawan — Fri, 23 Jul 2010 15:23:50 +0000

thank for idea, it’s work…

By: steven

steven — Mon, 14 Jun 2010 08:33:04 +0000

i seem to not be able to load the haar clasifier cascade from my files, can anyone help me?

By: giuseppe

giuseppe — Tue, 18 May 2010 03:16:30 +0000

Me too. On Windows, I get a run-time seg fault. But I cannot trace it.
G

By: Kronen

Kronen — Sat, 19 Dec 2009 05:49:08 +0000

I get a segmentation fault on cvCvtColor(img, gray, CV_RGB2GRAY);

Can anyone help me?

By: Sevick

Sevick — Fri, 20 Nov 2009 02:09:52 +0000

Idea is good, but on my PC it is still too slow comparing with OpenCV ShowImage…

[Edit: one link is enough dude..]

By: Azar

Azar — Tue, 03 Nov 2009 16:01:48 +0000

Hi,
thanks for the tutorial. I need to find out if i can convert QImage to IplImage. My requirement is to get the pixel co-ordinates when i click on some location of the image. and then convert it to IplImage and process.

Thank u

By: Spaï

Spaï — Mon, 17 Aug 2009 10:12:36 +0000

Hello Roy and all, thank you for your prompt response.

It is really a very good idea this “shared buffer”.
I only saw that on your blog.

I am a composer and I am currently developing software to make music with a webcam: NoizeKam
You can find here: http://blog.oliviergest.net/noizekam/

I am using OpenCV and STK, but now I use only PortAudio and I started to integrate QT for the interface and OpenGL.
I had already tested QT, but it slows down the execution.
I will try your method of shared buffer because I think it should speed up my soft and eat less CPU cycles.

Again thank you for sharing your knowledge (everyone does not, that’s a shame) and your help is so valuable in this area.

PS: translated from French into English by my friend Google