Human Detection With SimpleCV and Python

Transcription

1 Human Detection With SimpleCV and Python DIFFICULTY: MEDIUM PANGOLINPAD.YOLASITE.COM

2 SimpleCV Python wrapper for the Open Computer Vision (OpenCV) system Simple interface for complicated image processing Importable into a python program #!/usr/bin/python Import time Import SimpleCV

3 Installation SimpleCV is not included in the Raspbian distribution It also relies a set of python packages to work Install them all with: $ sudo apt-get install ipython python-opencv pythonscipy python-numpy python-pygame python-setuptools python-pip

4 Installation Use pip (you just installed it) to get the latest version of SimpleCV $ sudo pip install And finally make sure everything is up-to-date $ sudo add-apt-repository ppa:gijzelaar/opencv2.3 $ sudo apt-get update

5 The SimpleCV Shell A shell is a user interface SimpleCV has a dedicated one you can start just by typing: $ simplecv The following command may be necessary the 1 st time: $ python -m SimpleCV. init.

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7 USB camera Designed for USB cameras, not the Raspberry Pi s camera module If you have a USB webcam, make a python program like this: from SimpleCV import Camera # Initialize the camera cam = Camera() # Capture and image and display it cam.getimage().show()

8 Camera module You can set things up so that the camera module appears as a USB webcam Or you can use the raspistill command to save an image, then get SimpleCV to look at that

9 Example code from SimpleCV import show, Image import os # Capture an image os.system( raspistill n w 500 h 500 o image.jpg ) # Save the image in a variable img = Image( image.jpg ) # Display it on screen img.show() This takes & displays a 500x500 pixel image named image.jpg on the screen

10 Continuous loop from SimpleCV import Display, Image Import time display = Display() print "I launched a window" # Loop until window is closed while not display.isdone(): os.system( raspistill n w 500 h 500 o image.jpg ) img = Image( image.jpg ) # Here s where you d put any image processing img.save(display) time.sleep(0.1) print "You closed the window"

11 Haar-like features Haar-like features are used to compare portions of an image Using the relative brightness of two adjacent blocks of pixels, distinct blocks are found in an image Human eyes are generally darker than their cheeks If an image has two dark Haar features above two light ones, it s probably a face

12 findhaarfeatures() This function built into SimpleCV can be used to find 8 different things: Forward-looking faces Profile faces Eyes Noses Mouths Ears Upper bodies Lower bodies

13 from SimpleCV import Display, Image display = Display() print "I launched a window" # Loop until window is closed while not display.isdone(): os.system( raspistill n w 500 h 500 o image.jpg ) img = Image( image.jpg ) # Look for a face faces = img.findhaarfeatures('face') if faces is not None: # Draw a box around the face faces.draw() # Say how many faces were found print %s faces detected % len(faces) img.save(display)

14 Drawing on an image Be default, draw() places a green square at the specified coordinates You can change this to anything you like with the following code icon = Image( iconname.jpg ) img.dl().blit(icon, coordinates=faces) Include this in place of the line: faces.draw() In the code on the previous slide

15 A fun example [video/image] I ll have this running in real-time after the talk, so if you ve ever wondered what you d look like with a moustache

16 More practical applications Security camera that only records human activity Want to keep an eye on your sports car But don t want a hard-drive full of the neighbour's cat Robot vision Identify people to greet them Robotic pet that follows you around

17 Performance Smaller features are harder to identify Greater distance = smaller features Can t detect eyes across the room Smaller image resolution = smaller features But high resolution = more image to work through = slower detection Try different features for different situations

18 Useful Links SimpleCV beginner s guide: SLIDES/Computer%20Vision/Computer%20Vision%20using %20SimpleCV%20and%20the%20Raspberry%20Pi.pdf Camera module as a camera SimpleCV recognises: