CODEWITHSUNDEEP
opencvobject-detectionhaar-classifier
star_2014
star_2014

Reputation: 3

Haar feature implementation on OpenCv

Can someone explain me what the functions in haar.cpp file (in OpenCv) do? And which function actually does the Haar feature evaluation?

Upvotes: 0

Views: 2883

Answers (1)

ivan_a
ivan_a

Reputation: 613

This is how HAAR module works in my understanding:

You need an image and a cascade file. Cascade file contains a "tree". You start at the top of the tree and propagate downwards. Every node specifies what type of haar feature you have to extract and a threshold (http://opencv.jp/opencv-2.2_org/c/objdetect_cascade_classification.html).

Here is the pseudocode

  1. Take a 2D Image patch where you want to detect an object. Lets say it's size is 64x64 grayscale pixels.

  2. Start propagating the cascade tree, by computing the node's haar-like feature and comparing its value with the threshold stored in the node. If bigger go to the left otherwise go to right, let's say. Continue until a tree leaf is reached.

If you disable all optimizations, some of this computations happen between lines 797 to 813 haar.cpp.

Upvotes: 2

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