How to get a color range from a "Drag Box" in OpenCV 2.4 - opencv

Question

I'm using Python and OpenCV 2.4. I'm trying to get a HSV average from an area selected by dragging the mouse, much like in the camShift example provided by OpenCV. But I want the X, Y of the selected color instances in a video feed.
I've been hacking at the onmouse function in camShift. I feel it is close to want I want, I just can't seem to extract the mean HSV values of the area selected. I know I could probably get this done with a for loop, but trying to make it as responsive as possible.
def onmouse(self, event, x, y, flags, param):
x, y = np.int16([x, y]) # BUG
if event == cv2.EVENT_LBUTTONDOWN:
self.drag_start = (x, y)
self.tracking_state = 0
if self.drag_start:
if flags & cv2.EVENT_FLAG_LBUTTON:
h, w = 480, 640 # self.frame.shape[:2]
xo, yo = self.drag_start
x0, y0 = np.maximum(0, np.minimum([xo, yo], [x, y]))
x1, y1 = np.minimum([w, h], np.maximum([xo, yo], [x, y]))
self.selection = None
if x1-x0 > 0 and y1-y0 > 0:
self.selection = (x0, y0, x1, y1)
else:
self.drag_start = None
if self.selection is not None:
self.tracking_state = 1

Answer 1

Ok. It's crude, but this seems to be a lot closer than I was:
import numpy as np
import cv2
import video
class App(object):
def __init__(self, video_src):
#self.cam = video.create_capture(video_src)
self.cam = cv2.VideoCapture(0)
ret, self.frame = self.cam.read()
cv2.namedWindow('camshift')
cv2.setMouseCallback('camshift', self.onmouse)
self.selection = None
self.drag_start = None
self.tracking_state = 0
self.show_backproj = False
def onmouse(self, event, x, y, flags, param):
x, y = np.int16([x, y]) # BUG
if event == cv2.EVENT_LBUTTONDOWN:
self.drag_start = (x, y)
self.tracking_state = 0
if self.drag_start:
if flags & cv2.EVENT_FLAG_LBUTTON:
h, w = self.frame.shape[:2]
xo, yo = self.drag_start
x0, y0 = np.maximum(0, np.minimum([xo, yo], [x, y]))
x1, y1 = np.minimum([w, h], np.maximum([xo, yo], [x, y]))
self.selection = None
if x1-x0 > 0 and y1-y0 > 0:
self.selection = (x0, y0, x1, y1)
else:
self.drag_start = None
if self.selection is not None:
self.tracking_state = 1
def show_hist(self):
bin_count = self.hist.shape[0]
bin_w = 24
img = np.zeros((256, bin_count*bin_w, 3), np.uint8)
for i in xrange(bin_count):
h = int(self.hist[i])
cv2.rectangle(img, (i*bin_w+2, 255), ((i+1)*bin_w-2, 255-h), (int(180.0*i/bin_count), 255, 255), -1)
img = cv2.cvtColor(img, cv2.COLOR_HSV2BGR)
cv2.imshow('hist', img)
def run(self):
while True:
ret, self.frame = self.cam.read()
self.frame = cv2.blur(self.frame,(3,3))
vis = self.frame.copy()
hsv = cv2.cvtColor(self.frame, cv2.COLOR_BGR2HSV)
mask = cv2.inRange(hsv, np.array((0., 60., 32.)), np.array((180., 255., 255.)))
mask2 = mask.copy()
if self.selection:
x0, y0, x1, y1 = self.selection
self.track_window = (x0, y0, x1-x0, y1-y0)
hsv_roi = hsv[y0:y1, x0:x1]
mask_roi = mask[y0:y1, x0:x1]
#cv2.norm(hsv_roi)
dHSV = cv2.mean(hsv_roi)
h, s, v = int(dHSV[0]), int(dHSV[1]), int(dHSV[2])
hist = cv2.calcHist( [hsv_roi], [0], mask_roi, [16], [0, 180] )
cv2.normalize(hist, hist, 0, 255, cv2.NORM_MINMAX);
self.hist = hist.reshape(-1)
self.show_hist()
vis_roi = vis[y0:y1, x0:x1]
cv2.bitwise_not(vis_roi, vis_roi)
vis[mask == 0] = 0
if self.tracking_state == 1:
self.selection = None
cv2.imshow('camshift', vis)
if self.tracking_state == 1:
if h > 159:
h = 159
if s > 235:
s = 235
if v > 235:
v = 235
if h < 20:
h = 20
if s < 20:
s = 20
if v < 20:
v = 20
thresh = cv2.inRange(hsv,np.array(((h-20), (s-20), (v-20))), np.array(((h+20), (s+20), (v+20))))
thresh2 = thresh.copy()
# find contours in the threshold image
contours,hierarchy = cv2.findContours(thresh,cv2.RETR_LIST,cv2.CHAIN_APPROX_SIMPLE)
#best_cnt = 1
max_area = 0
for cnt in contours:
area = cv2.contourArea(cnt)
if area > max_area:
max_area = area
best_cnt = cnt
# finding centroids of best_cnt and draw a circle there
M = cv2.moments(best_cnt)
cx,cy = int(M['m10']/M['m00']), int(M['m01']/M['m00'])
print cx, cy
cv2.circle(thresh2,(cx,cy),20,255,-1)
cv2.imshow('thresh',thresh2)
ch = 0xFF & cv2.waitKey(5)
if ch == 27:
break
if ch == ord('b'):
self.show_backproj = not self.show_backproj
cv2.destroyAllWindows()
if __name__ == '__main__':
import sys
try: video_src = sys.argv[1]
except: video_src = 0
print __doc__
App(video_src).run()
I hack-sawed Rahman's example and camShift