CascadeClassifier

About

Haar Cascade Classifier implementation, tools and docs.

This repository revives the classic Viola–Jones cascade trainer that used to ship with OpenCV (the legacy opencv_traincascade program plus its companion utilities) so it can keep building against modern OpenCV releases. It contains:

• a stand-alone trainer library and CLI (traincascade/) that can train a multi-stage cascade with Haar, LBP or HOG features;
• the original sample-preparation, annotation, detection and visualisation utilities (tools/);
• documentation on the relevant command-line flags (docs/).

Repository layout

Path	Contents
traincascade/	Cascade trainer library (lib/), traincascade executable and unit tests (test/).
traincascade/lib/include/	Public headers, fully Doxygen-annotated.
traincascade/lib/src/	Implementation; the o_*.cpp files are extracted from OpenCV's legacy ML module and retain their original copyright headers.
tools/createsamples/	opencv_createsamples — generates .vec files of positives.
tools/annotation/	opencv_annotation — interactive bounding-box tool.
tools/detection/Cpp/	C++ sample that runs a trained cascade on an image.
tools/detection/Python/	Equivalent Python detection sample.
tools/visualisation/	opencv_visualisation — visualises the stages of a trained cascade.
docs/	Markdown documentation of CLI parameters.
external/	CMake helpers (e.g. FindOpenCV.cmake).

Building

The project uses CMake (>= 3.10) and depends on OpenCV (core, imgproc, imgcodecs, ml, objdetect, highgui).

cmake -S . -B build -G Ninja
cmake --build build

A coverage-enabled build is also available under build-coverage/.

Architecture overview

The trainer is structured as a small hierarchy of legacy OpenCV ML classes plus cascade-specific subclasses:

CvStatModel
  └── CvDTree                       (CART decision tree, o_cvdtree.h)
        └── CvBoostTree              (boosting weak learner, o_cvboostree.h)
              └── CvCascadeBoostTree (cascade-aware weak tree)

CvStatModel
  └── CvBoost                        (AdaBoost ensemble, o_cvboost.h)
        └── CvCascadeBoost           (single cascade stage, boost.h)

CvCascadeClassifier                  (multi-stage trainer, cascadeclassifier.h)

Feature evaluation is decoupled through CvFeatureEvaluator (traincascade_features.h) with concrete subclasses CvHaarEvaluator, CvLBPEvaluator and CvHOGEvaluator. Sample streaming is handled by CvCascadeImageReader (imagestorage.h). Refer to the Doxygen comments in traincascade/lib/include/ for class- and method-level documentation.

Documentation

• Cascade trainer parameters
• createsamples parameters
• Useful links and references
• Test-suite README

License

See LICENSE. Files derived from OpenCV's legacy ML module (traincascade/lib/src/o_*.cpp and the tools under tools/) keep their original Intel / OpenCV Foundation copyright headers.