Official source code for TLD
Objective-C C++ C
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TLD (aka Predator)

TLD is an algorithm for tracking of unknown objects in unconstrained video streams. The object of interest is defined by a bounding box in a single frame. TLD simultaneously tracks the object, learns its appearance and detects it whenever it appears in the video.

1. License

This source code is released under the GPL license version 3.0.  For alternative licensing options contact the main author:

2. Project website

You can find more information about TLD at: This includes the description of TLD, links to research papers, posters and the licensing options.

3. Wiki

Many questions regarding TLD are already answered at the following wiki: These questions include installation and common errors. Make sure to check the wiki first.

4. Discussion group

If you do not find your answer in the wiki, ask the question directly at the following discussion group: There are currently around 250 participants and it is likely you will get the answer soon.  

5. Feedback

Predator learns from its errors; let us do the same in this community! Therefore, if you get an answer that was not covered in the wiki, please update the wiki so that other people do not have to face the same problem. The wiki is freely editable at the moment. 

6. Citations

In case you use TLD in an academic work, please cite the following paper:

 author = {Kalal, Z and Matas, J and Mikolajczyk, K},
 journal = {Conference on Computer Vision and Pattern Recognition},
 title = {{P-N Learning: Bootstrapping Binary Classifiers by Structural Constraints}},
 year = {2010}


(c) 2011 Zdenek Kalal,