106 lines
3.5 KiB
Python
106 lines
3.5 KiB
Python
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#!/usr/bin/python
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"""
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This program is a demonstration of ellipse fitting.
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Trackbar controls threshold parameter.
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Gray lines are contours. Colored lines are fit ellipses.
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Original C implementation by: Denis Burenkov.
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Python implementation by: Roman Stanchak, James Bowman
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"""
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import sys
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import urllib2
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import random
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import cv
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def contour_iterator(contour):
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while contour:
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yield contour
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contour = contour.h_next()
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class FitEllipse:
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def __init__(self, source_image, slider_pos):
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self.source_image = source_image
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cv.CreateTrackbar("Threshold", "Result", slider_pos, 255, self.process_image)
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self.process_image(slider_pos)
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def process_image(self, slider_pos):
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"""
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This function finds contours, draws them and their approximation by ellipses.
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"""
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stor = cv.CreateMemStorage()
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# Create the destination images
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image02 = cv.CloneImage(self.source_image)
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cv.Zero(image02)
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image04 = cv.CreateImage(cv.GetSize(self.source_image), cv.IPL_DEPTH_8U, 3)
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cv.Zero(image04)
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# Threshold the source image. This needful for cv.FindContours().
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cv.Threshold(self.source_image, image02, slider_pos, 255, cv.CV_THRESH_BINARY)
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# Find all contours.
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cont = cv.FindContours(image02,
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stor,
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cv.CV_RETR_LIST,
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cv.CV_CHAIN_APPROX_NONE,
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(0, 0))
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for c in contour_iterator(cont):
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# Number of points must be more than or equal to 6 for cv.FitEllipse2
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if len(c) >= 6:
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# Copy the contour into an array of (x,y)s
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PointArray2D32f = cv.CreateMat(1, len(c), cv.CV_32FC2)
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for (i, (x, y)) in enumerate(c):
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PointArray2D32f[0, i] = (x, y)
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# Draw the current contour in gray
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gray = cv.CV_RGB(100, 100, 100)
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cv.DrawContours(image04, c, gray, gray,0,1,8,(0,0))
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# Fits ellipse to current contour.
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(center, size, angle) = cv.FitEllipse2(PointArray2D32f)
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# Convert ellipse data from float to integer representation.
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center = (cv.Round(center[0]), cv.Round(center[1]))
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size = (cv.Round(size[0] * 0.5), cv.Round(size[1] * 0.5))
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angle = -angle
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# Draw ellipse in random color
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color = cv.CV_RGB(random.randrange(256),random.randrange(256),random.randrange(256))
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cv.Ellipse(image04, center, size,
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angle, 0, 360,
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color, 2, cv.CV_AA, 0)
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# Show image. HighGUI use.
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cv.ShowImage( "Result", image04 )
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if __name__ == '__main__':
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if len(sys.argv) > 1:
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source_image = cv.LoadImage(sys.argv[1], cv.CV_LOAD_IMAGE_GRAYSCALE)
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else:
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url = 'https://code.ros.org/svn/opencv/trunk/opencv/samples/c/stuff.jpg'
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filedata = urllib2.urlopen(url).read()
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imagefiledata = cv.CreateMatHeader(1, len(filedata), cv.CV_8UC1)
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cv.SetData(imagefiledata, filedata, len(filedata))
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source_image = cv.DecodeImage(imagefiledata, cv.CV_LOAD_IMAGE_GRAYSCALE)
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# Create windows.
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cv.NamedWindow("Source", 1)
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cv.NamedWindow("Result", 1)
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# Show the image.
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cv.ShowImage("Source", source_image)
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fe = FitEllipse(source_image, 70)
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print "Press any key to exit"
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cv.WaitKey(0)
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cv.DestroyWindow("Source")
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cv.DestroyWindow("Result")
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