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#! /usr/bin/env python
import sys
# import the necessary things for OpenCV
from opencv import cv
from opencv import highgui
#############################################################################
# definition of some constants
# how many bins we want for the histogram, and their ranges
hdims = 16
hranges = [[0, 180]]
# ranges for the limitation of the histogram
vmin = 10
vmax = 256
smin = 30
# the range we want to monitor
hsv_min = cv.cvScalar (0, smin, vmin, 0)
hsv_max = cv.cvScalar (180, 256, vmax, 0)
#############################################################################
# some useful functions
def hsv2rgb (hue):
# convert the hue value to the corresponding rgb value
sector_data = [[0, 2, 1],
[1, 2, 0],
[1, 0, 2],
[2, 0, 1],
[2, 1, 0],
[0, 1, 2]]
hue *= 0.1 / 3
sector = cv.cvFloor (hue)
p = cv.cvRound (255 * (hue - sector))
if sector & 1:
p ^= 255
rgb = {}
rgb [sector_data [sector][0]] = 255
rgb [sector_data [sector][1]] = 0
rgb [sector_data [sector][2]] = p
return cv.cvScalar (rgb [2], rgb [1], rgb [0], 0)
#############################################################################
# so, here is the main part of the program
if __name__ == '__main__':
# a small welcome
print "OpenCV Python wrapper test"
print "OpenCV version: %s (%d, %d, %d)" % (cv.CV_VERSION,
cv.CV_MAJOR_VERSION,
cv.CV_MINOR_VERSION,
cv.CV_SUBMINOR_VERSION)
# first, create the necessary windows
highgui.cvNamedWindow ('Camera', highgui.CV_WINDOW_AUTOSIZE)
highgui.cvNamedWindow ('Histogram', highgui.CV_WINDOW_AUTOSIZE)
# move the new window to a better place
highgui.cvMoveWindow ('Camera', 10, 40)
highgui.cvMoveWindow ('Histogram', 10, 270)
try:
# try to get the device number from the command line
device = int (sys.argv [1])
# got it ! so remove it from the arguments
del sys.argv [1]
except (IndexError, ValueError):
# no device number on the command line, assume we want the 1st device
device = 0
if len (sys.argv) == 1:
# no argument on the command line, try to use the camera
capture = highgui.cvCreateCameraCapture (device)
# set the wanted image size from the camera
highgui.cvSetCaptureProperty (capture,
highgui.CV_CAP_PROP_FRAME_WIDTH, 320)
highgui.cvSetCaptureProperty (capture,
highgui.CV_CAP_PROP_FRAME_HEIGHT, 240)
else:
# we have an argument on the command line,
# we can assume this is a file name, so open it
capture = highgui.cvCreateFileCapture (sys.argv [1])
# check that capture device is OK
if not capture:
print "Error opening capture device"
sys.exit (1)
# create an image to put in the histogram
histimg = cv.cvCreateImage (cv.cvSize (320,240), 8, 3)
# init the image of the histogram to black
cv.cvSetZero (histimg)
# capture the 1st frame to get some propertie on it
frame = highgui.cvQueryFrame (capture)
# get some properties of the frame
frame_size = cv.cvGetSize (frame)
# compute which selection of the frame we want to monitor
selection = cv.cvRect (0, 0, frame.width, frame.height)
# create some images usefull later
hue = cv.cvCreateImage (frame_size, 8, 1)
mask = cv.cvCreateImage (frame_size, 8, 1)
hsv = cv.cvCreateImage (frame_size, 8, 3 )
# create the histogram
hist = cv.cvCreateHist ([hdims], cv.CV_HIST_ARRAY, hranges, 1)
while 1:
# do forever
# 1. capture the current image
frame = highgui.cvQueryFrame (capture)
if frame is None:
# no image captured... end the processing
break
# mirror the captured image
cv.cvFlip (frame, None, 1)
# compute the hsv version of the image
cv.cvCvtColor (frame, hsv, cv.CV_BGR2HSV)
# compute which pixels are in the wanted range
cv.cvInRangeS (hsv, hsv_min, hsv_max, mask)
# extract the hue from the hsv array
cv.cvSplit (hsv, hue, None, None, None)
# select the rectangle of interest in the hue/mask arrays
hue_roi = cv.cvGetSubRect (hue, selection)
mask_roi = cv.cvGetSubRect (mask, selection)
# it's time to compute the histogram
cv.cvCalcHist (hue_roi, hist, 0, mask_roi)
# extract the min and max value of the histogram
min_val, max_val, min_idx, max_idx = cv.cvGetMinMaxHistValue (hist)
# compute the scale factor
if max_val > 0:
scale = 255. / max_val
else:
scale = 0.
# scale the histograms
cv.cvConvertScale (hist.bins, hist.bins, scale, 0)
# clear the histogram image
cv.cvSetZero (histimg)
# compute the width for each bin do display
bin_w = histimg.width / hdims
for i in range (hdims):
# for all the bins
# get the value, and scale to the size of the hist image
val = cv.cvRound (cv.cvGetReal1D (hist.bins, i)
* histimg.height / 255)
# compute the color
color = hsv2rgb (i * 180. / hdims)
# draw the rectangle in the wanted color
cv.cvRectangle (histimg,
cv.cvPoint (i * bin_w, histimg.height),
cv.cvPoint ((i + 1) * bin_w, histimg.height - val),
color, -1, 8, 0)
# we can now display the images
highgui.cvShowImage ('Camera', frame)
highgui.cvShowImage ('Histogram', histimg)
# handle events
k = highgui.cvWaitKey (10)
if k == '\x1b':
# user has press the ESC key, so exit
break
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