How read an image with openCV and publish it using ROS and CvBridge

from sensor_msgs.msg import Image
from cv_bridge import CvBridge, CvBridgeError
import cv2

image = cv2.imread("myimage",1)

pub = rospy.Publisher('image_topic', Image)

pub.publish(bridge.cv2_to_imgmsg(image, "bgr8"))


CvBridge é uma bilbioteca do ROS que fornece uma interface entre ROS e OpenCV. Leia mais em: http://wiki.ros.org/cv_bridge/Tutorials/ConvertingBetweenROSImagesAndOpenCVImagesPython

Ros Rate

Como manter uma particular taxa 

para um laço: usando rospy.Rate

Leia mais em: http://wiki.ros.org/rospy/Overview/Time 

rate = rospy.Rate(10) # 10hz
while not rospy.is_shutdown():
    # ...
    rate.sleep()

Converter .png para .gif
convert -delay 100 -loop 0 *.png result.gif

Converter .mpeg para .png
 ffmpeg -i video.mp4 -r 1 -f image2 image_%05d.png

Places I've visited :)

visited 9 states (4%)
Create your own visited map of The World or Triposo world travel guide for Android

Transform matrix in a vector - Python using numpy

1 a = np.arange(10).reshape(2,5)
2 print a
3 a = a .ravel
4 print a
_____________________________________________________
2: array([[0, 1, 2, 3, 4],
       [5, 6, 7, 8, 9]])

4: array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])

numpy ndarray to cvmat

1 import cv
2 print type(image)
3 new_image = cv.fromarray(image)
4 print type(new_image)
______________________________________________________:
2: cv2.cv.cvmat
4: type 'numpy.ndarray 

Ternary operator python - Operador ternário python

>>> a = (False,True)[True]
>>> a
 True
>>> a = (False,True)[False]
>>> a
False
>>> a= (False, True) [3%2 == 0]
False