Latest Python blimp detection script

Tested with blimp movie, outputs blip centroids in command line. Color
tracking needs to be improved in different lighting conditions.

Author: garonson

BlimpDetect-8-28.py

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+#!/usr/bin/python
+
+# import system modules
+import cv2.cv as cv
+#import cv
+global imghsv
+
+# purpose: using HSV thresholds, detects blue, yellow and purple objects in a video stream in three new windows
+# 	   1) a black/white stream showing objects matching threshold values (window "threshold")
+#	   2) a black/color stream tracking the locations of the objects in their respective colors (window "final")
+#	   3) a full-color stream showing the original video and the bounding boxes of detected objects (window "real")
+
+# things that would make this script more useful for future tests: 
+# 	   1) GUI HSV threshold and minimum pixel size sliders like Kevin has added to the Canny Edge Detection program
+#	   2) Limit the number of blue/yellow/purple objects that can be detected at one time to one
+
+# source from:
+# http://stackoverflow.com/questions/8152504/tracking-two-different-colors-using-opencv-2-3-and-python
+
+# definitely works with Mac OSX, Python 2.7, and OpenCV library
+
+# to modify color thresholds, change the cv.Scalar values in the InRange method in the gettresholdedimg function below
+
+def getthresholdedimg(im):
+
+	# this function take RGB image.Then convert it into HSV for easy colour detection 
+	# and threshold it with yellow and blue part as white and all other regions as black.Then return that image
+	
+	global imghsv
+	imghsv = cv.CreateImage(cv.GetSize(im),8,3)
+	
+	# Convert image from RGB to HSV
+	cv.CvtColor(im,imghsv,cv.CV_BGR2HSV)
+					
+	# creates images for blue 
+	imgblue   = cv.CreateImage(cv.GetSize(im),8,1)
+	
+	# creates blank image to which color images are added
+	imgthreshold = cv.CreateImage(cv.GetSize(im),8,1)
+	
+	# determine HSV color thresholds for yellow, blue, and green
+	# cv.InRange(src, lowerbound, upperbound, dst)
+	# for imgblue, lowerbound is 95, and upperbound is 115
+	cv.InRangeS(imghsv, cv.Scalar(55,100,100), cv.Scalar(155,255,255), imgblue  )
+	
+	# add color thresholds to blank 'threshold' image
+	cv.Add(imgthreshold, imgblue,   imgthreshold)
+
+	return imgthreshold
+
+# capture from m4v
+capture = cv.CaptureFromFile('/Users/glenaronson/Desktop/blimp_large.m4v') #cv.CaptureFromCAM(0)
+frame = cv.QueryFrame(capture)
+frame_size = cv.GetSize(frame)
+
+# blank images to which images are added later
+test = cv.CreateImage(cv.GetSize(frame),8,3)
+img2 = cv.CreateImage(cv.GetSize(frame),8,3)
+
+# three windows that will open upon execution
+cv.NamedWindow("Real",0)
+
+# blank lists to store coordinates of blue blob
+blue   = []
+
+
+while(1):
+	# captures feed from video in color
+	color_image = cv.QueryFrame(capture)
+	
+	# ??
+	imdraw = cv.CreateImage(cv.GetSize(frame), 8, 3)
+	
+	# ??
+	cv.SetZero(imdraw)
+	cv.Flip(color_image,color_image, 1)
+	cv.Smooth(color_image, color_image, cv.CV_GAUSSIAN, 3, 0)
+	# ??
+	imgbluethresh = getthresholdedimg(color_image)
+	cv.Erode(imgbluethresh, imgbluethresh, None,  3)
+	cv.Dilate(imgbluethresh, imgbluethresh, None, 10)
+	# ??
+	img2 = cv.CloneImage(imgbluethresh)
+	# ??
+	storage = cv.CreateMemStorage(0)
+	contour = cv.FindContours(imgbluethresh, storage, cv.CV_RETR_CCOMP, cv.CV_CHAIN_APPROX_SIMPLE)
+	
+	# blank list into which points for bounding rectangles around blobs are appended
+	points = []	
+
+	# this is the new part here. ie use of cv.BoundingRect()
+	while contour:
+		
+		# Draw bounding rectangles
+		bound_rect = cv.BoundingRect(list(contour))
+		contour = contour.h_next()
+		#print contour  # not sure why print contour
+		
+		# for more details about cv.BoundingRect,see documentation
+		pt1 = (bound_rect[0], bound_rect[1])
+		pt2 = (bound_rect[0] + bound_rect[2], bound_rect[1] + bound_rect[3])
+		points.append(pt1)
+		points.append(pt2)
+		cv.Rectangle(color_image, pt1, pt2, cv.CV_RGB(255,0,0), 1)
+
+		# calculating centroids
+		centroidx = cv.Round((pt1[0]+pt2[0])/2)
+		centroidy = cv.Round((pt1[1]+pt2[1])/2)
+
+		# identifying if blue blobs exist and adding centroids to corresponding lists.
+		# note that the lower and upper bounds correspond to the the lower and upper bounds
+		# in the getthresholdedimg(im): function earlier in the script.
+		# e.g., yellow has a lowerbound of 95 and upper bound of 115 in both sections of code
+		if (55 < cv.Get2D(imghsv,centroidy,centroidx)[0] < 155): 
+			blue.append((centroidx,centroidy))
+
+	# draw colors in windows; exception handling is used to avoid IndexError.	
+	# after drawing is over, centroid from previous part is removed from list by pop. 
+	# so in next frame, centroids in this frame become initial points of line to draw	
+	
+	# draw blue box around blue blimp blob
+	try:
+		cv.Circle(imdraw, blue[1], 5, (255,0,0))
+		cv.Line(imdraw, blue[0], blue[1], (255,0,0), 3, 8, 0) 
+		blue.pop(0)
+		print("centroid x:" + str(centroidx))
+		print("centroid y:" + str(centroidy))
+		print("")		
+	except IndexError:
+		print "no blimp detected"	
+
+
+	# adds 
+	cv.Add(test,imdraw,test)
+	
+	# display windows previously created
+	cv.ShowImage("Real", color_image) 
+	
+	if cv.WaitKey(33) == 1048603:
+		cv.DestroyWindow("Real")
+		break
+######################################################