cvsize.hs

data CvSize = CvSize { sizeWidth :: CInt, sizeHeight :: CInt }
               deriving (Show, Eq)

instance Storable CvSize where
    sizeOf _ = (#size CvSize)
    alignment _ = alignment (undefined :: CInt)
    peek ptr = do
        w <- (#peek CvSize, width) ptr
        h <- (#peek CvSize, height) ptr
        return (CvSize w h)
    poke ptr (CvSize w h) = do
        (#poke CvSize, width) ptr w
        (#poke CvSize, height) ptr h

liftCvSize ::(RealFrac c, Num b) => (b -> c) -> CvSize -> CvSize
liftCvSize f (CvSize w h) = CvSize (f' w) (f' h)
    where f' = toFromIntegral f

liftCvSize2 :: (Num b, Num b1, RealFrac a) => (b -> b1 -> a) -> CvSize -> CvSize -> CvSize
liftCvSize2 f (CvSize w1 h1) (CvSize w2 h2) = CvSize (f' w1 w2) (f' h1 h2)
    where f' = toFromIntegral2 f

instance AdditiveGroup CvSize where
  zeroV = CvSize 0 0
  (^+^) = liftCvSize2 (+)
  negateV = liftCvSize (0-)

instance VectorSpace CvSize where
  type Scalar CvSize = Double -- todo: use CInt instead of Double here?
  a *^ s = liftCvSize (a*) s

example.hsc

{-# LANGUAGE ForeignFunctionInterface, EmptyDataDecls #-}

module AI.CV.OpenCV.CV where

import Foreign.C.Types
import Foreign.Ptr

#include <cxcore.h>
#include <cv.h>

class IplArrayType a

data CvArr
instance IplArrayType CvArr

data IplImage
instance IplArrayType IplImage


foreign import ccall unsafe "cv.h cvCanny"
  c_cvCanny :: Ptr CvArr -> Ptr CvArr -> CDouble -> CDouble -> CInt -> IO ()

cvCanny :: (IplArrayType i1, IplArrayType i2) =>
           Ptr i1 -> Ptr i2 -> CDouble -> CDouble -> CInt -> IO ()
cvCanny src dst threshold1 threshold2 apertureSize =
  c_cvCanny (fromArr src) (fromArr dst) (realToFrac threshold1) (realToFrac threshold2) apertureSize
  

facedetect.py

#!/usr/bin/python
"""
This program is demonstration for face and object detection using haar-like features.
The program finds faces in a camera image or video stream and displays a red box around them.

Original C implementation by:  ?
Python implementation by: Roman Stanchak, James Bowman
"""
import sys
import cv2.cv as cv
from optparse import OptionParser

# Parameters for haar detection
# From the API:
# The default parameters (scale_factor=2, min_neighbors=3, flags=0) are tuned
# for accurate yet slow object detection. For a faster operation on real video
# images the settings are:
# scale_factor=1.2, min_neighbors=2, flags=CV_HAAR_DO_CANNY_PRUNING,
# min_size=<minimum possible face size

min_size = (20, 20)
image_scale = 2
haar_scale = 1.2
min_neighbors = 2
haar_flags = 0

def detect_and_draw(img, cascade):
    # allocate temporary images
    gray = cv.CreateImage((img.width,img.height), 8, 1)
    small_img = cv.CreateImage((cv.Round(img.width / image_scale),
                   cv.Round (img.height / image_scale)), 8, 1)

    # convert color input image to grayscale
    cv.CvtColor(img, gray, cv.CV_BGR2GRAY)

    # scale input image for faster processing
    cv.Resize(gray, small_img, cv.CV_INTER_LINEAR)

    cv.EqualizeHist(small_img, small_img)

    if(cascade):
        t = cv.GetTickCount()
        faces = cv.HaarDetectObjects(small_img, cascade, cv.CreateMemStorage(0),
                                     haar_scale, min_neighbors, haar_flags, min_size)
        t = cv.GetTickCount() - t
        print "detection time = %gms" % (t/(cv.GetTickFrequency()*1000.))
        if faces:
            for ((x, y, w, h), n) in faces:
                # the input to cv.HaarDetectObjects was resized, so scale the
                # bounding box of each face and convert it to two CvPoints
                pt1 = (int(x * image_scale), int(y * image_scale))
                pt2 = (int((x + w) * image_scale), int((y + h) * image_scale))
                cv.Rectangle(img, pt1, pt2, cv.RGB(255, 0, 0), 3, 8, 0)

    cv.ShowImage("result", img)

if __name__ == '__main__':

    parser = OptionParser(usage = "usage: %prog [options] [filename|camera_index]")
    parser.add_option("-c", "--cascade", action="store", dest="cascade", type="str", help="Haar cascade file, default %default", default = "../../data/haarcascades/haarcascade_frontalface_alt.xml")
    (options, args) = parser.parse_args()

    cascade = cv.Load(options.cascade)

    if len(args) != 1:
        parser.print_help()
        sys.exit(1)

    input_name = args[0]
    if input_name.isdigit():
        capture = cv.CreateCameraCapture(int(input_name))
    else:
        capture = None

    cv.NamedWindow("result", 1)

    if capture:
        frame_copy = None
        while True:
            frame = cv.QueryFrame(capture)
            if not frame:
                cv.WaitKey(0)
                break
            if not frame_copy:
                frame_copy = cv.CreateImage((frame.width,frame.height),
                                            cv.IPL_DEPTH_8U, frame.nChannels)
            if frame.origin == cv.IPL_ORIGIN_TL:
                cv.Copy(frame, frame_copy)
            else:
                cv.Flip(frame, frame_copy, 0)

            detect_and_draw(frame_copy, cascade)

            if cv.WaitKey(10) >= 0:
                break
    else:
        image = cv.LoadImage(input_name, 1)
        detect_and_draw(image, cascade)
        cv.WaitKey(0)

    cv.DestroyWindow("result")