Hough circle transform based blink detection

examples/blinkdet/blinkdet.py

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+from ctypes import *
+
+import subprocess
+import numpy as np
+import os
+import cv2
+import time
+
+os.system('go build -o blinkdet.so -buildmode=c-shared blinkdet.go')
+pigo = cdll.LoadLibrary('./blinkdet.so')
+os.system('rm blinkdet.so')
+
+MAX_NDETS = 2024
+ARRAY_DIM = 6
+
+# define class GoPixelSlice to map to:
+# C type struct { void *data; GoInt len; GoInt cap; }
+class GoPixelSlice(Structure):
+	_fields_ = [
+		("pixels", POINTER(c_ubyte)), ("len", c_longlong), ("cap", c_longlong),
+	]
+
+# Obtain the camera pixels and transfer them to Go trough Ctypes.
+def process_frame(pixs):
+	dets = np.zeros(ARRAY_DIM * MAX_NDETS, dtype=np.float32)
+	pixels = cast((c_ubyte * len(pixs))(*pixs), POINTER(c_ubyte))
+	
+	# call FindFaces
+	faces = GoPixelSlice(pixels, len(pixs), len(pixs))
+	pigo.FindFaces.argtypes = [GoPixelSlice]
+	pigo.FindFaces.restype = c_void_p
+
+	# Call the exported FindFaces function from Go. 
+	ndets = pigo.FindFaces(faces)
+	data_pointer = cast(ndets, POINTER((c_longlong * ARRAY_DIM) * MAX_NDETS))
+	
+	if data_pointer :
+		buffarr = ((c_longlong * ARRAY_DIM) * MAX_NDETS).from_address(addressof(data_pointer.contents))
+		res = np.ndarray(buffer=buffarr, dtype=c_longlong, shape=(MAX_NDETS, 5,))
+
+		# The first value of the buffer aray represents the buffer length.
+		dets_len = res[0][0]
+		res = np.delete(res, 0, 0) # delete the first element from the array
+
+		# We have to consider the pupil pair added into the list.
+		# That's why we are multiplying the detection length with 3.
+		dets = list(res.reshape(-1, 5))[0:dets_len*3]
+		return dets
+
+# initialize the camera
+cap = cv2.VideoCapture(0)
+cap.set(cv2.CAP_PROP_FRAME_WIDTH, 640)
+cap.set(cv2.CAP_PROP_FRAME_HEIGHT, 480)
+
+# Changing the camera resolution introduce a short delay in the camera initialization. 
+# For this reason we should delay the object detection process with a few milliseconds.
+time.sleep(0.4)
+
+showPupil = True
+showEyes = False
+
+while(True):
+	ret, frame = cap.read()
+	pixs = np.ascontiguousarray(frame[:, :, 1].reshape((frame.shape[0], frame.shape[1])))
+	pixs = pixs.flatten()
+
+	# Verify if camera is intialized by checking if pixel array is not empty.
+	if np.any(pixs):
+		dets = process_frame(pixs) # pixs needs to be numpy.uint8 array
+
+		if dets is not None:
+			# We know that the detected faces are taking place in the first positions of the multidimensional array.
+			for det in dets:
+				if det[4] == 1: # 1 == face; 0 == pupil
+					cv2.rectangle(frame, 
+							(int(det[1])-int(det[2]/2), int(det[0])-int(det[2]/2)), 
+							(int(det[1])+int(det[2]/2), int(det[0])+int(det[2]/2)), 
+							(0, 0, 255), 2
+						)
+				else:
+					if showPupil:
+						x1, x2 = int(det[0])-int(det[2]*1.2), int(det[0])+int(det[2]*1.2)
+						y1, y2 = int(det[1])-int(det[2]*1.2), int(det[1])+int(det[2]*1.2)
+						subimg = frame[x1:x2, y1:y2]
+
+						if subimg is not None:
+							gray = cv2.cvtColor(subimg, cv2.COLOR_BGR2GRAY)
+							img_blur = cv2.medianBlur(gray, 3)
+
+							if img_blur is not None:
+								max_radius = int(det[2]*0.45)
+								circles = cv2.HoughCircles(img_blur, cv2.HOUGH_GRADIENT, 1, int(det[2]*0.3), 
+									param1=60, param2=18, minRadius=4, maxRadius=max_radius)
+								
+								if circles is not None:
+									circles = np.uint16(np.around(circles))
+									for i in circles[0, :]:
+										if i[2] < max_radius and i[2] > 0:
+											# Draw outer circle
+											print(i)
+											cv2.circle(frame, (int(det[1]), int(det[0])), i[2], (0, 255, 0), 2)
+											# Draw inner circle
+											cv2.circle(frame, (int(det[1]), int(det[0])), 2, (255, 0, 255), 3)
+											
+						cv2.circle(frame, (int(det[1]), int(det[0])), 4, (0, 0, 255), -1, 8, 0)
+
+					if showEyes:
+						cv2.rectangle(frame, 
+							(int(det[1])-int(det[2]), int(det[0])-int(det[2])), 
+							(int(det[1])+int(det[2]), int(det[0])+int(det[2])), 
+							(0, 255, 0), 2
+						)
+
+	cv2.imshow('', frame)
+
+	key = cv2.waitKey(1)
+	if key & 0xFF == ord('q'):
+		break
+	elif key & 0xFF == ord('w'):
+		showPupil = not showPupil
+	elif key & 0xFF == ord('e'):
+		showEyes = not showEyes
+
+cap.release()
+cv2.destroyAllWindows()