Using raspistill and raspivid

To capture images and videos using the Raspberry Pi Camera module, we need to use raspistill and raspivid utilities.

To capture an image, run the following command:

raspistill -o cam_module_pic.jpg

This will capture and save the image with name cam_module_pic.jpg in the current directory.

To capture a 20 second video with the camera module, run the following command:

raspivid –o test.avi –t 20000

This will capture and save the video with name test.avi in the current directory. Unlike fswebcam and avconv, raspistill and raspivid do not write anything to the console. So, you need to check the current directory for the output. Also, one can run the echo $? command to check whether these commands executed successfully. We can also mention the complete location of the file to be saved in these command, as shown in the following example:

raspistill -o /home/pi/book/output/cam_module_pic.jpg

Just like fswebcam, raspistill can be used to record the timelapse sequence. In our timelapse shell script, replace the line that contains fswebcam with the appropriate raspistill command to capture the timelapse sequence and use mencoder again to create the video. This is left as an exercise for the readers.

Now, let's take a look at the images taken with the Pi Camera under different lighting conditions.

The following is the image with normal lighting and the backlight:

The following is the image with only the backlight:

The following is the image with normal lighting and no backlight:

For NoIR camera usage in the night under low light conditions, use IR illuminator light for better results. You can get it online. A typical off-the-shelf LED IR illuminator suitable for our purpose will look like the one shown here:

Using picamera in Python with the Pi Camera module

The picamera is a Python package that provides a programming interface to the Pi Camera module. The most recent version of raspbian has picamera preinstalled. If you do not have it installed, you can install it using:

sudo apt-get install python-picamera

The following program quickly demonstrates the basic usage of the picamera module to capture an image:

import picamera
import time

with picamera.PiCamera() as cam:
    cam.resolution=(1024,768)
    cam.start_preview()
    time.sleep(5)
    cam.capture('/home/pi/book/output/still.jpg')

We have to import time and picamera modules first. cam.start_preview() will start the preview, and time.sleep(5) will wait for 5 seconds before cam.capture() captures and saves image in the specified file.

There is a built-in function in picamera for timelapse photography. The following program demonstrates its usage:

import picamera
import time

with picamera.PiCamera() as cam:
    cam.resolution=(1024,768)
    cam.start_preview()
    time.sleep(3)
    for count, imagefile in enumerate(cam.capture_continuous('/home/pi/book/output/image{counter:02d}.jpg')):
        print 'Capturing and saving ' + imagefile
        time.sleep(1)
        if count == 10:
            break

In the preceding code, cam.capture_continuous() is used to capture the timelapse sequence using the Pi camera module.

The Pi camera versus the webcam

Now, after using the webcam and the Pi Camera, it's a good time to understand the differences, the pros, and the cons of using these.

The Pi camera board does not use a USB port and is directly interfaced to the Pi. So, it provides better performance than a webcam in terms of the frame rate and resolution. We can directly use the picamera module in Python to work on images and videos. However, the Pi camera cannot be used with any other computer.

A webcam uses an USB port for interface, and because of that, it can be used with any computer. However, compared to the Pi Camera its performance, it is lower in terms of the frame rate and resolution.