Comments on: Fast & Furious face detection with OpenCV

By: Alex

Alex — Sat, 22 May 2010 04:58:57 +0000

Hi Deepak,

“facedetect started to work 2.5 time faster, even on ARM” – it is was on ARM11 and ARM Cortex-A8 – both are single core (no parallel calculation).

Aleksey

By: Deepak

Deepak — Thu, 20 May 2010 10:29:20 +0000

Hi Aleksey,

You got 2.5 times gain on ARM. Was it on dual core or quad core ? And is this gain only due to parallelization ?

Regrads,
Deepak

By: Qun

Qun — Tue, 20 Apr 2010 13:43:03 +0000

Hi Aleksey, can you tell me, how to use the “performance.exe” ? I use it like this “performance.exe -data test.xml -info test.txt -w 32 -h 22 -sf 1.1″,but I get the result–0 hits, 0 missed, 0 false, I think there is something wrong with my test.txt. I really
can’t sure how to creat the test.txt. I am annoyed! Can you help me?
thank for your help!

regards

By: Michael

Michael — Thu, 15 Apr 2010 00:39:50 +0000

Hi there thanks for your article! I’ve been porting the OpenCV Haar Detection algorithm to our company’s MCU. In your approach for optimizing the detector, did you use the
CV_HAAR_SCALE_IMAGE parameter? For our particular system it was more favorable to scale the images instead of the features, but is there any difference on the quality?

Also in cvSetImagesForHaarClassifierCascade did you turn on the CV_ADJUST_FEATURES and CV_ADJUST_WEIGHTS options?
For CV_ADJUST_FEATURES the source code’s comment said something about aligning blocks, is that really necessary? And I couldn’t quite understand what CV_ADJUST_WEIGHTS was trying to do at all, is there any significant difference in quality with these options?

Thanks in advance.

By: choy

choy — Thu, 01 Apr 2010 06:54:16 +0000

Hi Andrey

Great, firstly thank to reply my comment

Btw I still have question about your comment.

Why haartraining can fall in to infinite loop? In my experiment it’s happen if the results of previous stages HR =1 and FA =0. So I try free code from MATLAB center to check adaboost algorithms. But as I know it will never infinite although HR =1 and FA =0. So I don’t know what is the problem. Would you please which part in the haartraing code it makes infinite?

thank for your help

regards

By: Andrey Soldatov

Andrey Soldatov — Wed, 31 Mar 2010 08:01:18 +0000

Hi, please see http://www.computer-vision-software.com/blog/2009/11/faq-opencv-haartraining/ (FAQ: OpenCV Haartraining). Shortly,

1. Don’t build 40 stages, use 24, 20 or less;

2. All your positive images will be rescaled to the same size during creating vec file so you can use any sizes of positive images maintaining proportions;

3. Negative images must have much bigger size than positive samples, size 160×120 is insufficient, use 1280×1024 or more. If you take small background images, haartraining will not be able to extract negative samples for high stages. The more stages you use, the bigger negative images you need.

4. Haartraining can fall into infinite loop, unfortunately. Try to stop it, change negative images and restart the program. It will start from last successful stage.

By: choy

choy — Mon, 29 Mar 2010 20:11:04 +0000

Hi Aleksey

Thank for your kindness upload your experiment in this blog. Btw I have some questions about your experiment

1. How about the size image in training data set ? all of them (both of positive and negative samples) with size 20×20?

2. I have run my first experiment. Positive data set is come from FRGC data base (700 images with size 24×24) and negative set is come from background image (1394 image swith size 160 x120). I use 40 stages, but unfortunately for the 13th stages the time consuming very long (more than 2 days) so would you please tell me what is my problem?

thank for your help

regards

By: Alex

Alex — Sun, 28 Feb 2010 13:16:06 +0000

Hi Anh,

We use another cascade + unique parameters.

By: Anh

Anh — Sat, 27 Feb 2010 07:55:29 +0000

Hi Aleksey, can you tell me, how did you get the 99,6% Hit Rate with the cascade(s) given in OpenCV? I’ve made an exprience with 800 images, each of them has 1 (and only one) frontal face, and got a Hit Rate of 30%. Here are the main lines in my programme:
char* cascade_file_name = “c:\\program files\\opencv\\data\\haarcascades\\haarcascade_frontalface_alt_tree.xml”;
CvHaarClassifierCascade* cascade = (CvHaarClassifierCascade*)cvLoad(cascade_file_name,0,0,0);
…
image = cvLoadImage(image_file_name);
gray = cvCreateImage(cvSize(image->width,image->height),8,1);
cvCvtColor(image,gray,CV_BGR2GRAY);
faces = cvHaarDetectObjects(gray,cascade,storage,1.1,2,0,cvSize(30,30));

By: Aleksey Kodubets

Aleksey Kodubets — Fri, 25 Dec 2009 01:58:35 +0000

No, this blog is only one place where we published our results.