Ask Your Question

tilted integral sum

asked 2013-02-19 12:21:22 -0600

Bibliarij gravatar image

updated 2013-02-19 12:23:32 -0600

Hello all! Is getting of tilted integral sum is necessarily for implementing Viola-Jones method? It seems to me that I saw some realizations which don't use tilted integral sum. This kind of integral image is some strange for me, I can't understand it...

edit retag flag offensive close merge delete

2 answers

Sort by ยป oldest newest most voted

answered 2013-02-19 16:40:31 -0600

SR gravatar image

No, the tilted integral image is not needed for the Viola Jones algorithm. In fact, the original Viola Jones Paper only uses upright (=untilted) Haar-like features.

In An Extended Set of Haar-Like Features for Rapid Object Detection, Rainer Lienhart , Jochen Maydt, ICIP 2002 the authors showed that extending the original feature set with those tilted Haar-like features improves performance, i.e. the false positive rate was reduced.

AFAIK the Haar-cascade detector in OpenCV uses both normal and tilted Haar-like features by default. I suppose other object classes benefit more from tilted features than faces.

edit flag offensive delete link more


I have one additional question. I use cascade file haarcascade_frontalface_alt.xml. Does the word "alt" mean that this cacsade doesn't use titled features?

Bibliarij gravatar imageBibliarij ( 2013-02-20 02:53:06 -0600 )edit

I have no clue.

SR gravatar imageSR ( 2013-02-20 04:56:05 -0600 )edit

ok, thanks

Bibliarij gravatar imageBibliarij ( 2013-02-20 05:11:50 -0600 )edit

answered 2013-02-19 13:47:28 -0600

berak gravatar image

updated 2013-02-19 13:50:53 -0600

yes, it's essential. please read the paper:

the viola-jones method is all about comparing rectangles, is the left one brighter than the right ? comparing rectangles

with those integral images, the check is just a handful of array lookups and adds, without, you'd have to loop through the image region every time, to get it's intensity

edit flag offensive delete link more


This is not the answer for the question. It is just about integral images in general.

SR gravatar imageSR ( 2013-02-19 16:34:04 -0600 )edit

well oh, i assumed the guy's problem was understanding integral images, thus a wish to sidestep them. my intent here was more to highlight the importance of the 'integral' thing for this.

berak gravatar imageberak ( 2013-02-19 16:56:46 -0600 )edit

Yeah, maybe I say not very clear... I can't understand only titled integral image. Anyway thanks to the answer!

Bibliarij gravatar imageBibliarij ( 2013-02-20 00:29:43 -0600 )edit

Hi Bibliarij, i'm facing same problem like you, I can't understand tilted integral sum. Did you understand it now?

livina gravatar imagelivina ( 2013-07-24 21:50:23 -0600 )edit

Question Tools


Asked: 2013-02-19 12:21:22 -0600

Seen: 714 times

Last updated: Feb 19 '13