Added minimum size threshold for blimp objects

Included 20 pixel x and y minimum for blimp like objects so only those
meeting these conditions will be 1) appended to centroid coordinate
lists which are used to calculate 3D position, and 2) surrounding by
the red bounding rectangle in the video being analyzed.

Author: garonson

BlimpDetect-9-22.py

@@ -0,0 +1,155 @@
+#!/usr/bin/python
+
+# import system modules
+import cv2.cv as cv
+#import cv
+global imghsv
+import math	
+
+# 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)  #55/155 original, 105 seems to be lower threshold needed to eliminate flag detection
+	
+	# add color thresholds to blank 'threshold' image
+	cv.Add(imgthreshold, imgblue,   imgthreshold)
+
+	return imgthreshold
+
+# capture from m4v
+capture = cv.CaptureFromFile('/Users/glenaronson/Desktop/WID_East.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)
+		# UPDATED 9/22: CALCULATED X AND Y SIZES OF BOUNDING BOX
+		xpix = math.fabs(pt1[0] - pt2[0])
+		ypix = math.fabs(pt1[1] - pt2[1])
+		print('xpix:'+str(xpix))
+		print('ypix:'+str(ypix))
+		print('pt1:'+str(pt1[0]))
+		print('pt2:'+str(pt2[0]))
+		
+		# UPDATED 9/22: 20 X AND Y PIXEL MINIMUM TO DRAW RED BOX AROUND BLIMP
+		if ypix > 20 and xpix > 20:
+			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
+		
+		# UPDATED 9/22: 20 X AND Y PIXEL MINIMUM TO BE APPENDED TO CENTROID LISTS
+		if (55 < cv.Get2D(imghsv,centroidy,centroidx)[0] < 155) and ypix > 20 and xpix > 20: 
+			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) 
+		print('xpix:'+str(xpix))
+		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
+######################################################