Hello,
I am new in Python and working on a project where I need to display in real
time the average hue a picture taken by a camera. For the moment, I use my
webcam, for simplicity reasons. I have read many articles and topics,
especially http://forum.arduino.cc/index.php?topic=137635.15;wap2 and
https://groups.google.com/d/msg/pyqtgraph/haiJsGhxTaQ/sTtMa195dHsJ and my
code comes directly from these examples. However, for some reason, the
graph doesn't want to plot.
As I said, I am very beginner and I don't understand exactly what I am
doing with the threads, but I have to use it and not the timer approach
because the final camera will need such implementation.
Here is the code I have :
########################
import cv2
import numpy as np
import pyqtgraph as pg
from pyqtgraph.Qt import QtGui, QtCore
import time
import sys
cap = cv2.VideoCapture(0)
frames = 10
app = QtGui.QApplication([])
average_hue_array = np.empty(frames)
win = pg.GraphicsWindow()
win.setWindowTitle('Real time plotting of the average hue of an image')
p1 = win.addPlot()
plt = pg.plot()
def update(average_hue_array):
plt.plot(average_hue_array, clear=True)
class Reader(pg.QtCore.QThread):
newData = pg.QtCore.Signal(object)
def run(self):
for i in range(0,frames):
global avghue
# Take each frame
_, frame = cap.read()
# Convert BGR to HSV
imghsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
average_color_per_row = np.average(imghsv, axis=0)
average_color = np.average(average_color_per_row, axis=0)
avghue = average_color.item(0)
average_hue_array[i] = avghue
self.newData.emit(average_hue_array)
time.sleep(0.05)
print("average hue = {}".format(avghue))
k = cv2.waitKey(1) & 0xFF
if k == 27 or k == 'q':
cap.release()
cv2.destroyAllWindows()
sys.exit(0)
thread1 = Reader()
thread1.newData.connect(update)
thread1.start()
########################
I guess it is quite easy to solve and I probably miss something obvious.
Siemovit
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