I am curious of how difficult to write a face detect program. So I read the sample code and found it only about 100 Python statements long! So it is very hobbyist friendly.
I also find the camera capture image function as simple as Pygame.
*** OpenCV Python sample programs H:\fongvision|OpenCV-2.3.1\samples\python\ ***
# ****************************************************************************
# camera.py
# ****************************************************************************
import cv2.cv as cv
import time
cv.NamedWindow("camera", 1)
capture = cv.CaptureFromCAM(0)
while True:
img = cv.QueryFrame(capture)
cv.ShowImage("camera", img)
if cv.WaitKey(10) == 27:
break
# ****************************************************************************
# cv20squartes.py
# ****************************************************************************
"""
Find Squares in image by finding countours and filtering
"""
#Results slightly different from C version on same images, but is
#otherwise ok
import math
import cv2.cv as cv
def angle(pt1, pt2, pt0):
"calculate angle contained by 3 points(x, y)"
dx1 = pt1[0] - pt0[0]
dy1 = pt1[1] - pt0[1]
dx2 = pt2[0] - pt0[0]
dy2 = pt2[1] - pt0[1]
nom = dx1*dx2 + dy1*dy2
denom = math.sqrt( (dx1*dx1 + dy1*dy1) * (dx2*dx2 + dy2*dy2) + 1e-10 )
ang = nom / denom
return ang
def is_square(contour):
"""
Squareness checker
Square contours should:
-have 4 vertices after approximation,
-have relatively large area (to filter out noisy contours)
-be convex.
-have angles between sides close to 90deg (cos(ang) ~0 )
Note: absolute value of an area is used because area may be
positive or negative - in accordance with the contour orientation
"""
area = math.fabs( cv.ContourArea(contour) )
isconvex = cv.CheckContourConvexity(contour)
s = 0
if len(contour) == 4 and area > 1000 and isconvex:
for i in range(1, 4):
# find minimum angle between joint edges (maximum of cosine)
pt1 = contour[i]
pt2 = contour[i-1]
pt0 = contour[i-2]
t = math.fabs(angle(pt0, pt1, pt2))
if s <= t:s = t
# if cosines of all angles are small (all angles are ~90 degree)
# then its a square
if s < 0.3:return True
return False
def find_squares_from_binary( gray ):
"""
use contour search to find squares in binary image
returns list of numpy arrays containing 4 points
"""
squares = []
storage = cv.CreateMemStorage(0)
contours = cv.FindContours(gray, storage, cv.CV_RETR_TREE, cv.CV_CHAIN_APPROX_SIMPLE, (0,0))
storage = cv.CreateMemStorage(0)
while contours:
#approximate contour with accuracy proportional to the contour perimeter
arclength = cv.ArcLength(contours)
polygon = cv.ApproxPoly( contours, storage, cv.CV_POLY_APPROX_DP, arclength * 0.02, 0)
if is_square(polygon):
squares.append(polygon[0:4])
contours = contours.h_next()
return squares
def find_squares4(color_img):
"""
Finds multiple squares in image
Steps:
-Use Canny edge to highlight contours, and dilation to connect
the edge segments.
-Threshold the result to binary edge tokens
-Use cv.FindContours: returns a cv.CvSequence of cv.CvContours
-Filter each candidate: use Approx poly, keep only contours with 4 vertices,
enough area, and ~90deg angles.
Return all squares contours in one flat list of arrays, 4 x,y points each.
"""
#select even sizes only
width, height = (color_img.width & -2, color_img.height & -2 )
timg = cv.CloneImage( color_img ) # make a copy of input image
gray = cv.CreateImage( (width,height), 8, 1 )
# select the maximum ROI in the image
cv.SetImageROI( timg, (0, 0, width, height) )
# down-scale and upscale the image to filter out the noise
pyr = cv.CreateImage( (width/2, height/2), 8, 3 )
cv.PyrDown( timg, pyr, 7 )
cv.PyrUp( pyr, timg, 7 )
tgray = cv.CreateImage( (width,height), 8, 1 )
squares = []
# Find squares in every color plane of the image
# Two methods, we use both:
# 1. Canny to catch squares with gradient shading. Use upper threshold
# from slider, set the lower to 0 (which forces edges merging). Then
# dilate canny output to remove potential holes between edge segments.
# 2. Binary thresholding at multiple levels
N = 11
for c in [0, 1, 2]:
#extract the c-th color plane
cv.SetImageCOI( timg, c+1 );
cv.Copy( timg, tgray, None );
cv.Canny( tgray, gray, 0, 50, 5 )
cv.Dilate( gray, gray)
squares = squares + find_squares_from_binary( gray )
# Look for more squares at several threshold levels
for l in range(1, N):
cv.Threshold( tgray, gray, (l+1)*255/N, 255, cv.CV_THRESH_BINARY )
squares = squares + find_squares_from_binary( gray )
return squares
RED = (0,0,255)
GREEN = (0,255,0)
def draw_squares( color_img, squares ):
"""
Squares is py list containing 4-pt numpy arrays. Step through the list
and draw a polygon for each 4-group
"""
color, othercolor = RED, GREEN
for square in squares:
cv.PolyLine(color_img, [square], True, color, 3, cv.CV_AA, 0)
color, othercolor = othercolor, color
cv.ShowImage(WNDNAME, color_img)
WNDNAME = "Squares Demo"
def main():
"""Open test color images, create display window, start the search"""
cv.NamedWindow(WNDNAME, 1)
for name in [ "../c/pic%d.png" % i for i in [1, 2, 3, 4, 5, 6] ]:
img0 = cv.LoadImage(name, 1)
try:
img0
except ValueError:
print "Couldn't load %s\n" % name
continue
# slider deleted from C version, same here and use fixed Canny param=50
img = cv.CloneImage(img0)
cv.ShowImage(WNDNAME, img)
# force the image processing
draw_squares( img, find_squares4( img ) )
# wait for key.
if cv.WaitKey(-1) % 0x100 == 27:
break
if __name__ == "__main__":
main()
# ****************************************************************************
# drawing.py
# ****************************************************************************
#! /usr/bin/env python
from random import Random
import colorsys
print "OpenCV Python version of drawing"
import cv2.cv as cv
def random_color(random):
"""
Return a random color
"""
icolor = random.randint(0, 0xFFFFFF)
return cv.Scalar(icolor & 0xff, (icolor >> 8) & 0xff, (icolor >> 16) & 0xff)
if __name__ == '__main__':
# some "constants"
width = 1000
height = 700
window_name = "Drawing Demo"
number = 100
delay = 5
line_type = cv.CV_AA # change it to 8 to see non-antialiased graphics
# create the source image
image = cv.CreateImage( (width, height), 8, 3)
# create window and display the original picture in it
cv.NamedWindow(window_name, 1)
cv.SetZero(image)
cv.ShowImage(window_name, image)
# create the random number
random = Random()
# draw some lines
for i in range(number):
pt1 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
pt2 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
cv.Line(image, pt1, pt2,
random_color(random),
random.randrange(0, 10),
line_type, 0)
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# draw some rectangles
for i in range(number):
pt1 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
pt2 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
cv.Rectangle(image, pt1, pt2,
random_color(random),
random.randrange(-1, 9),
line_type, 0)
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# draw some ellipes
for i in range(number):
pt1 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
sz = (random.randrange(0, 200),
random.randrange(0, 200))
angle = random.randrange(0, 1000) * 0.180
cv.Ellipse(image, pt1, sz, angle, angle - 100, angle + 200,
random_color(random),
random.randrange(-1, 9),
line_type, 0)
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# init the list of polylines
nb_polylines = 2
polylines_size = 3
pt = [0,] * nb_polylines
for a in range(nb_polylines):
pt [a] = [0,] * polylines_size
# draw some polylines
for i in range(number):
for a in range(nb_polylines):
for b in range(polylines_size):
pt [a][b] = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
cv.PolyLine(image, pt, 1,
random_color(random),
random.randrange(1, 9),
line_type, 0)
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# draw some filled polylines
for i in range(number):
for a in range(nb_polylines):
for b in range(polylines_size):
pt [a][b] = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
cv.FillPoly(image, pt,
random_color(random),
line_type, 0)
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# draw some circles
for i in range(number):
pt1 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
cv.Circle(image, pt1, random.randrange(0, 300),
random_color(random),
random.randrange(-1, 9),
line_type, 0)
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# draw some text
for i in range(number):
pt1 = (random.randrange(-width, 2 * width),
random.randrange(-height, 2 * height))
font = cv.InitFont(random.randrange(0, 8),
random.randrange(0, 100) * 0.05 + 0.01,
random.randrange(0, 100) * 0.05 + 0.01,
random.randrange(0, 5) * 0.1,
random.randrange(0, 10),
line_type)
cv.PutText(image, "Testing text rendering!",
pt1, font,
random_color(random))
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# prepare a text, and get it's properties
font = cv.InitFont(cv.CV_FONT_HERSHEY_COMPLEX,
3, 3, 0.0, 5, line_type)
text_size, ymin = cv.GetTextSize("OpenCV forever!", font)
pt1 = ((width - text_size[0]) / 2, (height + text_size[1]) / 2)
image2 = cv.CloneImage(image)
# now, draw some OpenCV pub ;-)
for i in range(0, 512, 2):
cv.SubS(image2, cv.ScalarAll(i), image)
(r, g, b) = colorsys.hsv_to_rgb((i % 100) / 100., 1, 1)
cv.PutText(image, "OpenCV forever!",
pt1, font, cv.RGB(255 * r, 255 * g, 255 * b))
cv.ShowImage(window_name, image)
cv.WaitKey(delay)
# wait some key to end
cv.WaitKey(0)
# ****************************************************************************
# edge.py
# ****************************************************************************
#! /usr/bin/env python
print "OpenCV Python version of edge"
import sys
import urllib2
import cv2.cv as cv
# some definitions
win_name = "Edge"
trackbar_name = "Threshold"
# the callback on the trackbar
def on_trackbar(position):
cv.Smooth(gray, edge, cv.CV_BLUR, 3, 3, 0)
cv.Not(gray, edge)
# run the edge dector on gray scale
cv.Canny(gray, edge, position, position * 3, 3)
# reset
cv.SetZero(col_edge)
# copy edge points
cv.Copy(im, col_edge, edge)
# show the im
cv.ShowImage(win_name, col_edge)
if __name__ == '__main__':
if len(sys.argv) > 1:
im = cv.LoadImage( sys.argv[1], cv.CV_LOAD_IMAGE_COLOR)
else:
url = 'https://code.ros.org/svn/opencv/trunk/opencv/samples/c/fruits.jpg'
filedata = urllib2.urlopen(url).read()
imagefiledata = cv.CreateMatHeader(1, len(filedata), cv.CV_8UC1)
cv.SetData(imagefiledata, filedata, len(filedata))
im = cv.DecodeImage(imagefiledata, cv.CV_LOAD_IMAGE_COLOR)
# create the output im
col_edge = cv.CreateImage((im.width, im.height), 8, 3)
# convert to grayscale
gray = cv.CreateImage((im.width, im.height), 8, 1)
edge = cv.CreateImage((im.width, im.height), 8, 1)
cv.CvtColor(im, gray, cv.CV_BGR2GRAY)
# create the window
cv.NamedWindow(win_name, cv.CV_WINDOW_AUTOSIZE)
# create the trackbar
cv.CreateTrackbar(trackbar_name, win_name, 1, 100, on_trackbar)
# show the im
on_trackbar(0)
# wait a key pressed to end
cv.WaitKey(0)
# ****************************************************************************
# 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")
.END
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