The Raspberry Pi single-board computers are a great starting point for machine vision research. One of the many reasons why is the official Raspberry Pi Camera Module. The newer module: the Raspberry Pi Camera v2.1 uses a Sony IXM219 with an 8-megapixel sensor that can record high definition images and video.
Together, these systems are capable of running a growing number of Linux distributions. Using the Raspberry Pi Operating System (formerly Rasbian OS) and Python, it’s possible to do object detection, object tracking, and optical character recognition, just to name a few possibilities.
Notice of Non-Affiliation and Disclaimer: As of the publication date, we are not affiliated, associated, authorized, endorsed by, compensated by, or in any way officially connected with the Raspberry Pi Foundation, Arducam, HDMI Founders, HDMI Forum, or their owners, subsidiaries or affiliates.
Objectives
Today, I will cover how to get the Raspberry Pi Camera working out of the box, and a few pitfalls to avoid during your setup.
- Unboxing the Raspberry Pi Camera
- Attaching the Camera
- Still Image Capture Test
- Video Capture Test
Requirements
In a previous article, we configured the new Raspberry Pi 4 to run the Raspberry Pi OS. Today we will use the Raspberry Pi OS and the terminal to enable, configure, and test the camera.
- Raspberry Pi 3 or Pi 4 (Raspberry Pi 4 with 4 GB is featured here)
- Raspberry Pi Camera v2.1
- A working image of Raspberry Pi OS or Raspbian OS
- Internet Connection
- 5-volt Power Source for Raspberry Pi 4
- (Recommended) Anti-static work area
Getting Started
As with every electrical build, I recommend working at an anti-static workstation, or using a safely grounded wrist strap. This will bleed away your electrostatic charge and hopefully protect the life of your project. If you do not have these available, at the very least consider handling your Raspberry Pi and camera by the edges.
The Raspberry Pi Camera v2.1 ships with the required flexible flat cable and anti-static packaging. The camera lens will be covered with protective, semi-transparent tape that I will leave on for now.
Like the Raspberry Pi itself, the Pi Camera has 4 mounting holes that fit the metric M2 screw size. These are non-threaded holes, so you should plan on using locking nuts to keep everything in place.
Attaching the Camera
Your camera ships with a flexible flat cable that you should attach to the camera connector on the Raspberry Pi. Only one side of the ribbon end will have metallic contacts.
Locate the beige socket marked “camera.” Unlatch it by gently lifting up the black locking tab until you see a gap that the ribbon can fit into. Insert the ribbon cable with the metal ends facing the nearby HDMI connector.
Once the ribbon is in, push it down into the connector until the metal contacts are barely visible. Then latch the connector by gently pushing the black locking tab back down on both sides.
Boot into Raspberry Pi OS
Start the Raspberry Pi OS using your preferred means, and then open the terminal.
As a rule, we should update everything to the latest version. Enter the following, and then prepare to confirm the upgrades if needed…
sudo apt-get update
sudo apt-get upgrade
I should note my remote session disconnected during the upgrade. If this happens to you, just log back in and attempt to do another sudo apt-get upgrade. If you get an error message saying: “could not get lock,” this is a good indication your upgrade is still happening in the background. Give it about 10 minutes and keep retrying.
Next, it’s time to configure the Raspberry Pi to enable the camera and other important functions.
sudo raspi-config
Changing the Default Password
If you are still using the default username and password (pi and raspberry), then now would be a good time to change it.
Select “Change User Password”, then follow the on-screen instructions until you have your new password confirmed and ready to use.
Enabling the Camera
Enable the camera by selecting:
Interfacing options –> Camera –> Yes (Enable)
(Recommended) Expand the File System
To get the most out of your microSD card storage, you can expand the file system by navigating to:
Advanced Options –> Expand Filesystem
Exit Raspi-Config
Now navigate to “Finish.” Reboot if you are asked to, and then give your system a minute or two to restart.
Taking a Single Still Photo
Reopen the terminal.
Eagle-eyed readers might notice I’ve left the protective tape covering the Raspberry Pi lens. The tape is transparent enough to collect images without exposing the lens to dust, so I will leave it on for now. Just know that removing the tape will improve your photo quality from what you see here.
Back in the terminal, enter the following command…
raspistill -o singleFrame.jpg
After a short delay, you should be able to open the File Manager. Navigate to the /home/pi directory. There, you should see the captured image file: singleFrame.jpg.
By default the image will be saved to wherever you are in your directory structure when you run it. You can check your location in the terminal by typing:
pwd
…for “print working directory.” If you want your images saved elsewhere, you should include your intended path along with the file name.
Know Your Options
Return to the terminal and simply enter:
raspistill
The application will generate a help report, including a comprehensive list of commands. The authors were quite generous in enabling automatic adjustments for exposure and white balance by default. I won’t cover all the options here, but here are two functions that may be generally useful…
Rotating the Image
Now rotate the image 90 ° by entering:
raspistill -o rotatedFrame.jpg -rot 90
Essentially, this has rotated the image clockwise, bringing the top of the scene to the right. But note it did not change the aspect ratio of the file from 4:3 to 3:4.
For rotations, this application will accept positive integers ranging from 0 to 359.
This version is effective in 90 ° increments. If you enter a value other than 0, 90, 180, or 270; your entry will be reduced to match one of those four values. In other words: values 0 to 89 result in no rotation. Values 90 to 179 result in 90 ° rotation, and so on.
Mirroring the Image
To mirror the image horizontally or vertically, you can enter the -hf or -vh options.
raspistill -o mirroredFrame.jpg -hf
Alternatively, you can use the slightly more human-readable equivalents: –hflip and –vflip.
Recording Video Clips
You can record a 5-second test video. Return to the terminal, and enter:
raspivid -o videoTest.h264 -t 5000
The “5000” indicates a recording duration in milliseconds. This application can use the same rotation and mirroring options as before.
After a few seconds of recording, you can view it by navigating back to the /home/pi . Then open the .h264 video file by double-clicking it.
sudo apt-get install gpac
Then you can convert your video file (videoTest.h264) into an MP4 file (videoTest.mp4) like this:
MP4Box -add videoTest.h264 videoTest.mp4
This will create an MP4 version alongside the original. Like before, you can read the help file for raspivid by typing:
raspivid
Commands Used Today
sudo apt-get update
sudo apt-get upgrade
sudo raspi-config
raspistill -o singleFrame.jpg
pwd
raspistill
raspistill -o rotatedFrame.jpg -rot 90
raspistill -o mirroredFrame.jpg -hf
raspivid -o videoTest.h264 -t 5000
omxplayer videoTest.h264
sudo apt-get install gpac
MP4Box -add videoTest.h264 videoTest.mp4Closing Remarks
Along with rotating and mirroring the video, there are options for adjusting the frame rate. This is important to consider wherever the Raspberry Camera’s rolling shutter might create bizarre images of fast-rotating equipment.
The camera itself works with all models of the Raspberry Pi, going as far back as the Raspberry Pi 1. The official website says it will be in production until at least the year 2024. Third-party cameras such as the ArduCam are definitely worth considering, and the ArduCam has so far been compatible with all my Raspberry Pi Cameras applications so far.
References
| [1] | Raspberry Pi Foundation, “Raspberry Pi 4 Computer Model B,” [Online]. Available: https://static.raspberrypi.org/files/product-briefs/200521+Raspberry+Pi+4+Product+Brief.pdf. [Accessed 20 Aug. 2020]. |
| [2] | S. McManus and M. Cook, “How to Test the Raspberry Pi Camera Module,” Dummies.com, [Online]. Available: https://www.dummies.com/computers/raspberry-pi/test-raspberry-pi-camera-module/. [Accessed 20 Aug 2020]. |
| [3] | Raspberry Pi Foundation, “Camera Module V2,” Raspberry Pi Foundation, [Online]. Available: https://www.raspberrypi.org/products/camera-module-v2/. [Accessed 23 Aug. 2020]. |
| [4] | A. Rosebrock, “Install OpenCV 4 on Raspberry Pi 4 and Raspbian Buster,” PyImageSearch, 16 Sep. 2020. [Online]. Available: https://www.pyimagesearch.com/2019/09/16/install-opencv-4-on-raspberry-pi-4-and-raspbian-buster/. [Accessed 19 Aug. 2020]. |
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