Need explanation of Haar cascade code in xml

Question

I need to understand haar cascade code in xml,

can anyone explain how do we get the value inside treshold, rightval, and left val ? for example 4.0141958743333817e-003 do you know the formulas to calculate it ?

Thankyou,

Doni Prassetyo

Answer 1

Oh, it is simple!

Haar is a computer generated file. You DO NOT have to write it yourself. The computer "learn" some patterns via a lot of positive & false positive then write it in a haar files. To generate haar files, download OpenCV, take thousands positive and thousands negative. Generate a lot of image with a positive image pasted on a negative image then launch the learning. The more you have images, the more precise it will be to generate the haar file.

Then, when you 'use' the haar file, the computer will test the first pattern, if he find somewhere with this pattern, he will test the second on those region of image, then the third. This is why it is called a "CASCADE" method.

More info for OpenCV and Wikipedia(FR) -Badly, the english version was not so explicit and didn't show you the patterns.

EDIT: More informations on OpenCV Generate HAAR/LBT files

Hope it helped.