Ask Your Question
0

Haar Feature-based Cascade Classifier XML file argument

asked 2015-01-20 06:12:35 -0500

I'm working with face detection of Haar Feature-based Cascade Classifier. I have searched a lots but I still haven't found the exactly answer for the left_val and right_val in XML file (like this)

  <_>
        <!-- root node -->
        <feature>
            <rects>
                <_>3 7 14 4 -1.</_>
                <_>3 9 14 2 2.</_></rects>
            <tilted>0</tilted></feature>
        <threshold> 4.0141958743333817e-003 </threshold>
        <left_val> 0.0337941907346249 </left_val>
        <right_val> 0.8378106951713562 </right_val></_></_>
  <_>

The left_val and right_val are the return value of a feature ( alpha(i) * h(i) in Viola-jones paper), is it true. And if so, because h(i) is -1 or 1 so we must have left_val = - right_val but in face it isn't true. Can you guys give me some explanation to understand that? Thank you for your help! Sorry my English is not so good

edit retag flag offensive close merge delete

Comments

I think this guy explains it pretty well, and this answer even better. Basically it is the value that is used to calculate the final stage score.

StevenPuttemans gravatar imageStevenPuttemans ( 2015-01-20 06:49:06 -0500 )edit

1 answer

Sort by ยป oldest newest most voted
0

answered 2015-06-02 05:22:20 -0500

Hi Steven, Can you please tell also what exactly is alpha value? Is it included in the Haar Classifier XML arguments? Thanks Chris

edit flag offensive delete link more

Comments

I am sorry, I moved to using the LBP based features quite some time ago. Also the newer haar features based models trained by traincascade do not got this alpha value anymore. So can you please explain where you found that value?

StevenPuttemans gravatar imageStevenPuttemans ( 2015-06-02 08:14:45 -0500 )edit

I have found it in an Haar-like implementation included in HLS Video Library, provided with Xilinx Vivado HLS to help accelerate computer vision/image processing applications on FPGA Sadly no documentation is provided for that certain implementtion but i suspect that is based on opencv and an older type of Haar Feature-based Cascade Classifier XML, with a bit different structure [additional "alpha" argument]. Are you familiar of that kind of structure?

chris_x gravatar imagechris_x ( 2015-06-06 00:49:21 -0500 )edit

No I am not and this forum only focusses on actual OpenCV implementations. We cannot cover every single software out there which is based on OpenCV. So I guess you will need to find a HLS video library specific forum for that. Also, looking at this page I am afraid that this software is built upon a very old OpenCV implementation which is far from supported :)

StevenPuttemans gravatar imageStevenPuttemans ( 2015-06-06 08:35:46 -0500 )edit
1

:-) Thanks Steven

chris_x gravatar imagechris_x ( 2015-06-06 11:01:43 -0500 )edit
Login/Signup to Answer

Question Tools

3 followers

Stats

Asked: 2015-01-20 06:12:35 -0500

Seen: 566 times

Last updated: Jan 20 '15