Python OpenCV C++ Wrapper (CPython)

findface.cpp

#include <iostream>
#include <vector>
#include <opencv2/core/core.hpp>
#include <opencv2/contrib/contrib.hpp>
#include <opencv2/objdetect/objdetect.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>

int find_face(const char* cascade_file, const char* image_file)
{
  cv::CascadeClassifier cascade;
  if(cascade.load(std::string(cascade_file)))
  {
    cv::Mat frame = cv::imread(image_file);
    cv::Mat frame_gray;
    std::vector<cv::Rect> faces;
    cv::cvtColor(frame, frame_gray, CV_BGR2GRAY);
    cv::equalizeHist(frame_gray,frame_gray);
    cascade.detectMultiScale( frame_gray, faces, 1.1, 2, 0 |CV_HAAR_SCALE_IMAGE, cv::Size(30, 30) );
    for(int i = 0; i < (int)faces.size(); ++i)
    {
      cv::Point pt1 = faces[i].tl();
      cv::Size sz = faces[i].size();
      cv::Point pt2(pt1.x+sz.width, pt1.y+sz.height);
      cv::rectangle(frame, pt1, pt2, cv::Scalar(255));
    }
    cv::imshow("faces", frame);
    cv::waitKey(0);
  }
  else
  {
     std::cout << "Error: " << cascade_file << " is not a valid haarcascade file" << std::endl;
     return 1;
  }
  return 0;
}

opencvgpumodule.cpp

#include <Python.h>

extern int find_face(const char* cascade_file, const char* image_file);

static PyObject* find_face_system(PyObject *self, PyObject *args)
{
  const char* cascade_path;
  const char* image_path;
  if (PyArg_ParseTuple(args, "ss", &cascade_path, &image_path))
  {
    int status = find_face(cascade_path, image_path);
    return Py_BuildValue("i", status);
  }
  return NULL;
}

static PyMethodDef OpenCVGPUMethods[] = {
  {"find_face",  find_face_system, METH_VARARGS,
   "OpenCV GPU bindings."},
  {NULL, NULL, 0, NULL}        /* Sentinel */
};

#if PY_VERSION_HEX >= 0x03000000

/* Python 3.x code */

static struct PyModuleDef opencvgpu = {
   PyModuleDef_HEAD_INIT,
   "opencvgpu", /* name of module */
   NULL,        /* module documentation, may be NULL */
   -1,          /* size of per-interpreter state of the module,
                or -1 if the module keeps state in global variables. */
   OpenCVGPUMethods
};

PyMODINIT_FUNC
PyInit_opencvgpu(void)
{
  (void) PyModule_Create(&opencvgpu);
}

#else

/* Python 2.x code */

PyMODINIT_FUNC
initopencvgpu(void)
{
    (void) Py_InitModule("opencvgpu", OpenCVGPUMethods);
}

#endif

setup.py

import os
from distutils.core import setup, Extension
from subprocess import check_output

# Pkg-config function from https://gist.github.com/abergmeier/9488990

def pkgconfig(*packages, **kw):
    flag_map = {
        '-I': 'include_dirs',
        '-L': 'library_dirs',
        '-l': 'libraries'}
    
    env = os.environ.copy()
    # possible narrowing of PkgConfig environment variables
    
    for token in check_output(['pkg-config', '--libs', '--cflags', ' '.join(packages)], env=env).split():
        key = token[:2]
        try:
            arg = flag_map[key]
            value = token[2:]
        except KeyError:
            arg = 'extra_link_args'
            value = token
        
        kw.setdefault(arg, []).append(value)
    for key, value in kw.iteritems(): # remove duplicated
        kw[key] = list(set(value))
    return kw

opencv_deps = pkgconfig('opencv')

opencvgpumodule = Extension('opencvgpu',
                  define_macros = [('MAJOR_VERSION', '1'),
                                   ('MINOR_VERSION', '0')],
                  include_dirs = opencv_deps['include_dirs'],
                  libraries = opencv_deps['libraries'],
                  sources = ['opencvgpumodule.cpp', 'findface.cpp'])

setup (name = 'OpenCV GPU',
       version = '1.0',
       description = 'OpenCV GPU Bindings',
       author = 'Alexander Koumis and Matthew Carlis',
       author_email = '[email protected], [email protected]',
       url = 'https://docs.python.org/extending/building',
       long_description = '''
OpenCV GPU Bindings
''',
       ext_modules = [opencvgpumodule])

CPython wrapper example performing face detection (it doesn't actually use GPU but that's what will eventually be built with this).

Installation

sudo python setup.py install

Usage

import opencvgpu
# Haarcascade file is available in opencv source
opencvgpu.find_face('haarcascade_frontalface_default.xml', 'image.jpg')