Raspbian Stretch: Install OpenCV 3 + Python on your Raspberry Pi

It’s been over two years since the release of Raspbian Jessie. As of August 17th, 2017, the Raspberry Pi foundation has officially released the successor to Raspbian Jessie — Raspbian Stretch.

Just as I have done in previous blog posts, I’ll be demonstrating how to install OpenCV 3 with Python bindings on Raspbian Stretch.

If you are looking for previous installation instructions for different platforms, please consult this list:

Otherwise, let’s proceed with getting OpenCV 3 with Python bindings installed on Raspian Stretch!

The quick start video tutorial

If this is your first time installing OpenCV or you are just getting started with Linux I highly suggest that you watch the video below and follow along with me as you guide you step-by-step on how to install OpenCV 3 on your Raspberry Pi running Raspbian Stretch:

Otherwise, if you feel comfortable using the command line or if you have previous experience with Linux environments, feel free to use the text-based version of this guide below.

Assumptions

In this tutorial, I am going to assume that you already own a Raspberry Pi 3 with Raspbian Stretch installed.

If you don’t already have the Raspbian Stretch OS, you’ll need to upgrade your OS to take advantage of Raspbian Stretch’s new features.

To upgrade your Raspberry Pi 3 to Raspbian Stretch, you may download it here and follow these upgrade instructions (or these for the NOOBS route which is recommended for beginners). The former instructions take approximately 10 minutes to download via a torrent client and about 10 minutes to flash the SD card at which point you can power up and proceed to the next section.

Note: If you are upgrading your Raspberry Pi 3 from Raspbian Jessie to Raspbian Stretch, there is the potential for problems. Proceed at your own risk, and consult the Raspberry Pi forums for help.

Important: It is my recommendation that you proceed with a fresh install of Raspbian Stretch! Upgrading from Raspbian Jessie is not recommended.

Assuming that your OS is up to date, you’ll need one of the following for the remainder of this post:

  • Physical access to your Raspberry Pi 3 so that you can open up a terminal and execute commands
  • Remote access via SSH or VNC.

I’ll be doing the majority of this tutorial via SSH, but as long as you have access to a terminal, you can easily follow along.

Can’t SSH? If you see your Pi on your network, but can’t ssh to it, you may need to enable SSH. This can easily be done via the Raspberry Pi desktop preferences menu (you’ll need an HDMI cable and a keyboard/mouse) or running sudo service ssh start  from the command line of your Pi.

After you’ve changed the setting and rebooted, you can test SSH directly on the Pi with the localhost address. Open a terminal and type ssh pi@127.0.0.1  to see if it is working.

Keyboard layout giving you problems? Change your keyboard layout by going to the Raspberry Pi desktop preferences menu. I use the standard US Keyboard layout, but you’ll want to select the one appropriate for your keyboard or desire (any Dvorkac users out there?).

Installing OpenCV 3 on a Raspberry Pi 3 running Raspbian Stretch

If you’ve ever installed OpenCV on a Raspberry Pi (or any other platform before), you know that the process can be quite time consuming with many dependencies and pre-requisites that have to be installed. The goal of this tutorial is to thus guide you step-by-step through the compile and installation process.

In order to make the installation process go more smoothly, I’ve included timings for each step so you know when to take a break, grab a cup of coffee, and checkup on email while the Pi compiles OpenCV.

Let’s go ahead and get started installing OpenCV 3 on your Raspberry Pi 3 running Raspbian Stretch.

Step #1: Expand filesystem

Are you using a brand new install of Raspbian Stretch?

If so, the first thing you should do is expand your filesystem to include all available space on your micro-SD card:

And then select the “Advanced Options” menu item:

Figure 1: Select the “Advanced Options” item from the “raspi-config” menu.

Followed by selecting “Expand filesystem”:

Figure 2: Expanding the filesystem on your Raspberry Pi 3.

Once prompted, you should select the first option, “A1. Expand File System”, hit Enter on your keyboard, arrow down to the “<Finish>” button, and then reboot your Pi — you may be prompted to reboot, but if you aren’t you can execute:

After rebooting, your file system should have been expanded to include all available space on your micro-SD card. You can verify that the disk has been expanded by executing df -h and examining the output:

As you can see, my Raspbian filesystem has been expanded to include all 32GB of the micro-SD card.

However, even with my filesystem expanded, I have already used 15% of my 32GB card.

If you are using an 8GB card you may be using close to 50% of the available space, so one simple thing to do is to delete both LibreOffice and Wolfram engine to free up some space on your Pi:

After removing the Wolfram Engine and LibreOffice, you can reclaim almost 1GB!

Step #2: Install dependencies

This isn’t the first time I’ve discussed how to install OpenCV on the Raspberry Pi, so I’ll keep these instructions on the briefer side, allowing you to work through the installation process: I’ve also included the amount of time it takes to execute each command (some depend on your Internet speed) so you can plan your OpenCV + Raspberry Pi 3 install accordingly (OpenCV itself takes approximately 4 hours to compile — more on this later).

The first step is to update and upgrade any existing packages:

Timing: 2m 14s

We then need to install some developer tools, including CMake, which helps us configure the OpenCV build process:

Timing: 19s

Next, we need to install some image I/O packages that allow us to load various image file formats from disk. Examples of such file formats include JPEG, PNG, TIFF, etc.:

Timing: 21s

Just as we need image I/O packages, we also need video I/O packages. These libraries allow us to read various video file formats from disk as well as work directly with video streams:

Timing: 32s

The OpenCV library comes with a sub-module named highgui which is used to display images to our screen and build basic GUIs. In order to compile the highgui module, we need to install the GTK development library:

Timing: 1m 36s

Many operations inside of OpenCV (namely matrix operations) can be optimized further by installing a few extra dependencies:

Timing: 23s

These optimization libraries are especially important for resource constrained devices such as the Raspberry Pi.

Lastly, let’s install both the Python 2.7 and Python 3 header files so we can compile OpenCV with Python bindings:

Timing: 45s

If you’re working with a fresh install of the OS, it is possible that these versions of Python are already at the newest version (you’ll see a terminal message stating this).

If you skip this step, you may notice an error related to the Python.h header file not being found when running make to compile OpenCV.

Step #3: Download the OpenCV source code

Now that we have our dependencies installed, let’s grab the 3.3.0 archive of OpenCV from the official OpenCV repository. This version includes the dnn  module which we discussed in a previous post where we did Deep Learning with OpenCV (Note: As future versions of openCV are released, you can replace 3.3.0 with the latest version number):

Timing: 41s

We’ll want the full install of OpenCV 3 (to have access to features such as SIFT and SURF, for instance), so we also need to grab the opencv_contrib repository as well:

Timing: 37s

You might need to expand the command above using the “<=>” button during your copy and paste. The .zip in the 3.3.0.zip may appear to be cutoff in some browsers. The full URL of the OpenCV 3.3.0 archive is:

https://github.com/Itseez/opencv_contrib/archive/3.3.0.zip

Note: Make sure your opencv and opencv_contrib versions are the same (in this case, 3.3.0). If the versions numbers do not match up, then you’ll likely run into either compile-time or runtime errors.

Step #4: Python 2.7 or Python 3?

Before we can start compiling OpenCV on our Raspberry Pi 3, we first need to install pip , a Python package manager:

Timing: 33s

You may get a message that pip is already up to date when issuing these commands, but it is best not to skip this step.

If you’re a longtime PyImageSearch reader, then you’ll know that I’m a huge fan of both virtualenv and virtualenvwrapper. Installing these packages is not a requirement and you can absolutely get OpenCV installed without them, but that said, I highly recommend you install them as other existing PyImageSearch tutorials (as well as future tutorials) also leverage Python virtual environments. I’ll also be assuming that you have both virtualenv and virtualenvwrapper installed throughout the remainder of this guide.

So, given that, what’s the point of using virtualenv and virtualenvwrapper ?

First, it’s important to understand that a virtual environment is a special tool used to keep the dependencies required by different projects in separate places by creating isolated, independent Python environments for each of them.

In short, it solves the “Project X depends on version 1.x, but Project Y needs 4.x” dilemma. It also keeps your global site-packages neat, tidy, and free from clutter.

If you would like a full explanation on why Python virtual environments are good practice, absolutely give this excellent blog post on RealPython a read.

It’s standard practice in the Python community to be using virtual environments of some sort, so I highly recommend that you do the same:

Timing: 35s

Now that both virtualenv and virtualenvwrapper have been installed, we need to update our ~/.profile file to include the following lines at the bottom of the file:

In previous tutorials, I’ve recommended using your favorite terminal-based text editor such as vim , emacs , or nano to update the ~/.profile file. If you’re comfortable with these editors, go ahead and update the file to reflect the changes mentioned above.

Otherwise, you should simply use cat and output redirection to handle updating ~/.profile :

Now that we have our ~/.profile updated, we need to reload it to make sure the changes take affect. You can force a reload of your ~/.profile file by:

  1. Logging out and then logging back in.
  2. Closing a terminal instance and opening up a new one
  3. Or my personal favorite, just use the source command:

Note: I recommend running the source ~/.profile file each time you open up a new terminal to ensure your system variables have been setup correctly.

Creating your Python virtual environment

Next, let’s create the Python virtual environment that we’ll use for computer vision development:

This command will create a new Python virtual environment named cv using Python 2.7.

If you instead want to use Python 3, you’ll want to use this command instead:

Timing: 24s

Again, I can’t stress this point enough: the cv Python virtual environment is entirely independent and sequestered from the default Python version included in the download of Raspbian Stretch. Any Python packages in the global site-packages directory will not be available to the cv virtual environment. Similarly, any Python packages installed in site-packages of cv will not be available to the global install of Python. Keep this in mind when you’re working in your Python virtual environment and it will help avoid a lot of confusion and headaches.

How to check if you’re in the “cv” virtual environment

If you ever reboot your Raspberry Pi; log out and log back in; or open up a new terminal, you’ll need to use the workon command to re-access the cv virtual environment. In previous blog posts, I’ve seen readers use the mkvirtualenv command — this is entirely unneeded! The mkvirtualenv command is meant to be executed only once: to actually create the virtual environment.

After that, you can use workon and you’ll be dropped down into your virtual environment:

To validate and ensure you are in the cv virtual environment, examine your command line — if you see the text (cv) preceding your prompt, then you are in the cv virtual environment:

Figure 3: Make sure you see the “(cv)” text on your prompt, indicating that you are in the cv virtual environment.

Otherwise, if you do not see the (cv) text, then you are not in the cv virtual environment:

Figure 4: If you do not see the “(cv)” text on your prompt, then you are not in the cv virtual environment and need to run “source” and “workon” to resolve this issue.

To fix this, simply execute the source and workon commands mentioned above.

Installing NumPy on your Raspberry Pi

Assuming you’ve made it this far, you should now be in the cv virtual environment (which you should stay in for the rest of this tutorial). Our only Python dependency is NumPy, a Python package used for numerical processing:

Timing: 11m 12s

Be sure to grab a cup of coffee or go for a nice walk, the NumPy installation can take a bit of time.

Note: A question I’ve often seen is “Help, my NumPy installation has hung and it’s not installing!” Actually, it is installing, it just takes time to pull down the sources and compile. You can verify that NumPy is compiling and installing by running top . Here you’ll see that your CPU cycles are being used compiling NumPy. Be patient. The Raspberry Pi isn’t as fast as your laptop/desktop.

Step #5: Compile and Install OpenCV

We are now ready to compile and install OpenCV! Double-check that you are in the cv virtual environment by examining your prompt (you should see the (cv) text preceding it), and if not, simply execute workon :

Once you have ensured you are in the cv virtual environment, we can setup our build using CMake:

Timing: 2m 56s

Now, before we move on to the actual compilation step, make sure you examine the output of CMake!

Start by scrolling down the section titled Python 2 and Python 3 .

If you are compiling OpenCV 3 for Python 2.7, then make sure your Python 2 section includes valid paths to the Interpreter , Libraries , numpy and packages path , similar to my screenshot below:

Figure 6: Checking that Python 3 will be used when compiling OpenCV 3 for Raspbian Stretch on the Raspberry Pi 3.

Notice how the Interpreter points to our python2.7 binary located in the cv virtual environment. The numpy variable also points to the NumPy installation in the cv environment.

Similarly, if you’re compiling OpenCV for Python 3, make sure the Python 3 section looks like the figure below:

Figure 6: Checking that Python 3 will be used when compiling OpenCV 3 for Raspbian Stretch on the Raspberry Pi 3.

Again, the Interpreter points to our python3.5 binary located in the cv virtual environment while numpy points to our NumPy install.

In either case, if you do not see the cv virtual environment in these variables paths, it’s almost certainly because you are NOT in the cv virtual environment prior to running CMake!

If this is the case, access the cv virtual environment using workon cv and re-run the cmake command outlined above.

Configure your swap space size before compiling

Before you start the compile process, you should increase your swap space size. This enables OpenCV to compile with all four cores of the Raspberry PI without the compile hanging due to memory problems.

Open your /etc/dphys-swapfile  and then edit the CONF_SWAPSIZE  variable:

Notice that I’ve commented out the 100MB line and added a 1024MB line. This is the secret to getting compiling with multiple cores on the Raspbian Stretch.

If you skip this step, OpenCV might not compile.

To activate the new swap space, restart the swap service:

Note: It is possible to burn out the Raspberry Pi microSD card because flash memory has a limited number of writes until the card won’t work. It is highly recommended that you change this setting back to the default when you are done compiling and testing the install (see below). To read more about swap sizes corrupting memory, see this page.

Finally, we are now ready to compile OpenCV:

Timing: 1h 30m

Once OpenCV 3 has finished compiling, your output should look similar to mine below:

Figure 7: Our OpenCV 3 compile on Raspbian Stretch has completed successfully.

From there, all you need to do is install OpenCV 3 on your Raspberry Pi 3:

Timing: 52s

Step #6: Finish installing OpenCV on your Pi

We’re almost done — just a few more steps to go and you’ll be ready to use your Raspberry Pi 3 with OpenCV 3 on Raspbian Stretch.

For Python 2.7:

Provided your Step #5 finished without error, OpenCV should now be installed in /usr/local/lib/python2.7/site-pacakges . You can verify this using the ls command:

Note: In some cases, OpenCV can be installed in /usr/local/lib/python2.7/dist-packages (note the dist-packages rather than site-packages ). If you do not find the cv2.so bindings in site-packages , we be sure to check dist-packages .

Our final step is to sym-link the OpenCV bindings into our cv virtual environment for Python 2.7:

For Python 3:

After running make install , your OpenCV + Python bindings should be installed in /usr/local/lib/python3.5/site-packages . Again, you can verify this with the ls command:

I honestly don’t know why, perhaps it’s a bug in the CMake script, but when compiling OpenCV 3 bindings for Python 3+, the output .so file is named cv2.cpython-35m-arm-linux-gnueabihf.so (or some variant of) rather than simply cv2.so (like in the Python 2.7 bindings).

Again, I’m not sure exactly why this happens, but it’s an easy fix. All we need to do is rename the file:

After renaming to cv2.so , we can sym-link our OpenCV bindings into the cv virtual environment for Python 3.5:

Step #7: Testing your OpenCV 3 install

Congratulations, you now have OpenCV 3 installed on your Raspberry Pi 3 running Raspbian Stretch!

But before we pop the champagne and get drunk on our victory, let’s first verify that your OpenCV installation is working properly.

Open up a new terminal, execute the source and workon commands, and then finally attempt to import the Python + OpenCV bindings:

As you can see from the screenshot of my own terminal, OpenCV 3 has been successfully installed on my Raspberry Pi 3 + Python 3.5 environment:

Figure 8: Confirming OpenCV 3 has been successfully installed on my Raspberry Pi 3 running Raspbian Stretch.

Once OpenCV has been installed, you can remove both the opencv-3.3.0 and opencv_contrib-3.3.0 directories to free up a bunch of space on your disk:

However, be cautious with this command! Make sure OpenCV has been properly installed on your system before blowing away these directories. A mistake here could cost you hours in compile time.

Don’t forget to change your swap size back!

Open your  /etc/dphys-swapfile  and then edit the  CONF_SWAPSIZE  variable:

Notice that I’ve commented out the 1024MB line and uncommented the 100MB line.

If you skip this step, your memory card won’t last as long. As stated above, larger swap spaces may lead to memory corruption, so I recommend setting it back to 100MB.

To revert to the smaller swap space, restart the swap service:

Troubleshooting and FAQ

Q. When I try to execute mkvirtualenv and workon , I get a “command not found error”.

A. There are three reasons why this could be happening, all of them related to Step #4:

  1. Make certain that you have installed virtualenv and virtualenvwrapper via pip . You can check this by running pip freeze and then examining the output, ensuring you see occurrences of both virtualenv and virtualenvwrapper .
  2. You might not have updated your ~/.profile correctly. Use a text editor such as nano to view your ~/.profile file and ensure that the proper export and source commands are present (again, check Step #4 for the contents that should be appended to ~/.profile .
  3. You did not source your ~/.profile after editing it, rebooting, opening a new terminal, etc. Any time you open a new terminal and want to use a virtual environment, make sure you execute source ~/.profile to load the contents — this will give you access to the mkvirtualenv and workon commands.

Q. After I open a new terminal, logout, or reboot my Pi, I cannot execute mkvirtualenv or workon .

A. See reason #3 from the previous question.

Q. When I (1) open up a Python shell that imports OpenCV or (2) execute a Python script that calls OpenCV, I get an error: ImportError: No module named cv2 .

A. Unfortunately, this error is extremely hard to diagnose, mainly because there are multiple issues that could be causing the problem. To start, make sure you are in the cv virtual environment by using workon cv . If the workon command fails, then see the first question in this FAQ. If you’re still getting an error, investigate the contents of the site-packages directory for your cv virtual environment. You can find the site-packages directory in ~/.virtualenvs/cv/lib/python2.7/site-packages/ or ~/.virtualenvs/cv/lib/python3.5/site-packages/ (depending on which Python version you used for the install). Make sure that your sym-link to the cv2.so file is valid and points to an existing file.

Q. I’m running into other errors.

A. Feel free to leave a comment and I’ll try to provide guidance; however, please understand that without physical access to your Pi it can often be hard to diagnose compile/install errors. If you’re in a rush to get OpenCV up and running on your Raspberry Pi be sure to take a look at the Quickstart Bundle and Hardcopy Bundle of my book, Practical Python and OpenCV. Both of these bundles include a Raspbian .img file with OpenCV pre-configured and pre-installed. Simply download the .img file, flash it to your Raspberry Pi, and boot! This method is by far the easiest, hassle free method to getting started with OpenCV on your Raspberry Pi.

So, what’s next?

Congrats! You have a brand new, fresh install of OpenCV on your Raspberry Pi — and I’m sure you’re just itching to leverage your Raspberry Pi to build some awesome computer vision apps.

But I’m also willing to bet that you’re just getting started learning computer vision and OpenCV, and you’re probably feeling a bit confused and overwhelmed on where exactly to start.

Personally, I’m a big fan of learning by example, so a good first step would be to read this blog post on accessing your Raspberry Pi Camera with the picamera module. This tutorial details the exact steps you need to take to (1) capture photos from the camera module and (2) access the raw video stream.

And if you’re really interested in leveling-up your computer vision skills, you should definitely check out my book, Practical Python and OpenCV + Case Studies. My book not only covers the basics of computer vision and image processing, but also teaches you how to solve real world computer vision problems including face detection in images and video streams, object tracking in video, and handwriting recognition.

raspberry_pi_in_post

All code examples covered in the book are guaranteed to run on the Raspberry Pi 2 and Pi 3 as well! Most programs will also run on the B+ and Zero models, but might be a bit slow due to the limited computing power of the B+ and Zero.

So let’s put your fresh install of OpenCV on your Raspberry Pi to good use — just click here to learn more about the real-world projects you can solve using your Raspberry Pi + Practical Python and OpenCV .

Summary

In this blog post, we learned how to upgrade your Raspberry Pi 3‘s OS to Raspbian Stretch and to install OpenCV 3 with either Python 2.7 or Python 3 bindings.

If you are running a different version of Raspbian (such as Raspbian Wheezy) or want to install a different version of OpenCV (such as OpenCV 2.4), please consult the following tutorials:

Are you looking for a project to work on with your new install of OpenCV on Raspbian Stretch? Readers have been big fans of this post on Home surveillance and motion detection with the Raspberry Pi, Python, OpenCV, and Dropbox.

But before you go…

I tend to utilize the Raspberry Pi quite a bit on this blog, so if you’re interested in learning more about the Raspberry Pi + computer vision, enter your email address in the form below to be notified when these posts go live!

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161 Responses to Raspbian Stretch: Install OpenCV 3 + Python on your Raspberry Pi

  1. Hilman September 4, 2017 at 7:22 pm #

    Adrian. I want to ask something.
    I have the Raspberry Pi 2 (and its camera module), but I just don’t know what kind of project I can do with it.
    Since I am busy, if possible, I want to make a project that can contribute the most to what I am learning right now (mainly machine learning). Do you have any idea?
    I were thinking of using it for scrapping data, but do not know where to begin. I would be very happy if you could recommend some suggestions.

    Thanks!

    • Adrian Rosebrock September 5, 2017 at 9:18 am #

      Hi Hilman — the Raspberry Pi 2 is a bit underpowered so I wouldn’t recommend training a machine learning classifier on your Pi, but I could see deploying one. Have you considered training an image classifier to recognize a particular object on your laptop/desktop and then actually running it on your Raspberry Pi?

      Also, keep in mind that all chapters inside Practical Python and OpenCV will run on the Raspberry Pi. Go through any of those chapters and you can execute the projects on the Pi (such as face detection + tracking). Those chapters make for excellent starting points for projects.

      I hope that helps!

      • Hilman September 5, 2017 at 8:59 pm #

        Ah… I forgot about that book. Will take a look at it later. Thanks!

  2. Jorge September 5, 2017 at 4:40 am #

    Great post as always.

    I wanted to share a neat little trick: You can actually enable SSH on the RPi just by placing an empty “ssh” file (case sensitive!) in the root of the sd card (once Raspbian is flashed).
    This makes running a 100% “headless” RPi possible: From there you can keep working with SSH or enable VNC and see the desktop from there.

    • Adrian Rosebrock September 5, 2017 at 9:11 am #

      Wow, that’s a neat trick! Thanks for sharing Jorge.

  3. Hidenori Kaga September 5, 2017 at 8:09 am #

    Your page has been explained in an easy-to-understand and polite manner, so it’s always helpful very much.
    I immediately installed the CV with reference to this page.
    However, Python IDLE in the program menu causes an error in importing. How can I use CV from IDLE?

    • Adrian Rosebrock September 5, 2017 at 9:10 am #

      Hi Hidenori — as far as I understand, the GUI version of Python IDLE does not support virtual environments, thus you cannot use it. I would suggest you use IDLE via the command line (so you can access the Python virtual environment) or use Jupyter Notebooks. I hope that helps!

  4. Steve Nicholson September 5, 2017 at 3:26 pm #

    If you aren’t going to run the tests, you can save a fair amount of compile time by not including them. To do that, add “-D BUILD_TESTS=OFF” and “-D BUILD_PERF_TESTS=OFF” to the CMake command line.

  5. Abkul Orto September 6, 2017 at 6:41 am #

    Great tutorial.

    All your ” Quickstart Bundle and Hardcopy Bundle book, Practical Python and OpenCV” I bought are a jewel i am happy to have invested in.

    in your blog on “Drowsiness detection with OpenCV of May 8, 2017 in dlib, Facial Landmarks, Tutorials” you suggested :

    “If you intend on using a Raspberry Pi for this, I would:

    1. Use Haar cascades rather than the HOG face detector. While Haar cascades are less accurate, they are also faster.
    2. Use skip frames and only detect faces in every N frames. This will also speedup the pipeline.”

    I have Pi 3, Kindly do a tutorial with an example to implement the above options.

    • Adrian Rosebrock September 7, 2017 at 7:05 am #

      Hi Abkul — thank you for picking up a copy of Practical Python and OpenCV, I appreciate your support! And yes, I will be covering an updated drowsiness detector for the Raspberry Pi in the future. I can’t say exactly when this will be as I’m very busy finishing up the new deep learning book, but it will happen before the end of the year.

  6. Islam September 6, 2017 at 10:52 am #

    Where new blog about pixel by pixel for loops

    • Adrian Rosebrock September 7, 2017 at 7:01 am #

      I already covered the blog post you are referring to here. I’ll also be doing an updated one on OpenMP in the future.

  7. Rick Free September 6, 2017 at 1:37 pm #

    Followed step-by-step and it worked like a charm. Compile took about 4 hours, as expected. Thanks!

    • Adrian Rosebrock September 7, 2017 at 6:59 am #

      Congrats on getting OpenCV installed, Rick! Nice job.

  8. Galang Hakim September 7, 2017 at 9:18 am #

    Hi andrian

    thanks for sharing
    I have success installed opencv to raspberry pi 3
    thanks to your guidance

    but I wonder
    for compiling OpenCV 3 for Python 2.7 and python3.5
    the libraries, numpy and site packages only for phyton 3

    I tried for 3x
    the result are still same
    any idea about that ?

    • Adrian Rosebrock September 11, 2017 at 9:32 am #

      You would need to create two separate Python virtual environments. One for Python 2.7 and one for Python 3. Form there you can run CMake + make from inside each virtual environment to build OpenCV.

  9. Charles Horan September 7, 2017 at 2:13 pm #

    Worked like a charm..mind you I installed opencv3.3 rather than 3.1 … still worked great 😀

    • Adrian Rosebrock September 11, 2017 at 9:30 am #

      Congrats on getting OpenCV installed, Charles! Nice job.

  10. Larry Pechacek September 8, 2017 at 8:26 am #

    Upon following this latest tutorial The compile did hang up around 91% using 4 cores on RPi2. Following the tutorial RPi2 on Jessie however compiled on Stretch using all 4 cores without issue.

    • Adrian Rosebrock September 11, 2017 at 9:25 am #

      Thank you for sharing your experience, Larry!

  11. Andrew September 10, 2017 at 5:41 pm #

    I am following this install on a Pi 2b. If I backup the sd card – will it work on a Pi 3 ?

  12. Stephane September 12, 2017 at 3:12 am #

    Hi Adrian,

    I installed OpenCv on my raspberry pi3 (2017-08-16-raspbian-stretch) by following step by step your latest tutorial.
    The compilation went well and the result is similar to yours.

    When I launch a simple program, see what it returns me:

    (cv) pi@raspberrypi:~ $ sudo modprobe bcm2835-v4l2
    (cv) pi@raspberrypi:~ $ python script.py
    Unable to init server: Could not connect: Connection refused

    (video test:1029): Gtk-WARNING **: cannot open display:
    (cv) pi@raspberrypi:~ $

    This program works fine on my computer with Linux Mint.
    Thanks for your reply and sorry for my approximate English.

    Bonjour de France 🙂

    Stéphane.

    • Adrian Rosebrock September 12, 2017 at 7:13 am #

      How are you accessing your Raspberry Pi? Over SSH? Enable X11 forwarding when you SSH into your Pi:

      $ ssh -X pi@your_ip_address

  13. Stephane September 12, 2017 at 2:20 pm #

    Via ssh well on 🙂

    Ok I’ll try the x11 server activation

    cordially

  14. Chris September 14, 2017 at 6:24 am #

    The issue with the multi threaded build is the lack of size of the swap file. You need to increase it to something like 1GB for doing intensive builds.

  15. Michael September 14, 2017 at 4:23 pm #

    I tried serveral times and did follow your great tutorial in detail. Anyhow, I am not able to get the virtualenvwrapper working (and, due to this, I have issues later on).

    After the installation of virtualenv and virtualenvwrapper (both were successful, including the dependancies) and updating the ~/.profile file, I always get the error:

    pi@raspberrypi:~ $ source ~/.profile
    /usr/bin/python: No module named virtualenvwrapper
    virtualenvwrapper.sh: There was a problem running the initialization hooks.

    If Python could not import the module virtualenvwrapper.hook_loader,
    check that virtualenvwrapper has been installed for
    VIRTUALENVWRAPPER_PYTHON=/usr/bin/python and that PATH is
    set properly.

    I did not find any clue to overcome this problem.

    Any help is appreciated.

    • Adrian Rosebrock September 18, 2017 at 2:17 pm #

      Which Python version were you trying to install OpenCV + Python for? Python 2.7? Or Python 3?

      • Gerard October 5, 2017 at 1:16 am #

        I’m trying to do 2.7 and get the same error

        • Adrian Rosebrock October 6, 2017 at 5:11 pm #

          I would suggest explicitly setting your Python version for virtualenvwrapper inside your .profile file, like this:

    • Stephen Hayes September 20, 2017 at 1:50 pm #

      In setting up the ~/.profile, I had to add the line: “export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3” before “source /usr/local/bin/virtualenvwrapper.sh”. Otherwise, I got the “No module named virtualenvwrapper.hook_loader” error.

      • Eyal October 18, 2017 at 2:21 am #

        I also had to add export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3” otherwise I“No module named virtualenvwrapper.hook_loader” error.

        But what is the implication for the next step: mkvirtualenv cv -p python2

        Thanks

        • Adrian Rosebrock October 19, 2017 at 4:55 pm #

          It should have have an impact.

  16. Tom September 17, 2017 at 6:06 am #

    Just a word of warning: Stretch takes more space than Jessie (~4GB vs ~3GB) so to prevent OpenCV from building on a 8GB card.

    • Adrian Rosebrock September 18, 2017 at 2:09 pm #

      Thanks for sharing, Tom!

  17. Stephen Hayes September 18, 2017 at 4:16 pm #

    In setting up the ~/.profile, I had to add the line: “export VIRTUALENVWRAPPER_PYTHON=/usr/bin/python3” before “source /usr/local/bin/virtualenvwrapper.sh”. Otherwise, I got the “No module named virtualenvwrapper.hook_loader” error.

  18. Stephen Hayes September 20, 2017 at 10:18 pm #

    Another note: It is possible to run the make with 4 cores. Stretch suffers a bit from software bloat, so the 2GB of memory isn’t sufficient to compile with 4 cores. Edit /etc/dphys-swapfile
    and change CONF_SWAPSIZE to 2048 and reboot. You can then do make -j4. you also need to do the same thing to install dlib as that will also hang under stretch when it runs out of memory.

    • Adrian Rosebrock September 21, 2017 at 7:15 am #

      Great point Stephen, thank you for sharing.

  19. toukir September 22, 2017 at 2:23 am #

    why can’t I import cv2 directly from python shell? but when I go to terminal and write work on and import cv2 then it works.
    But I like to import cv2 from the script. so what can I do for that? I am using python 2.7 and pi3.
    please help me.

    • Adrian Rosebrock September 22, 2017 at 8:54 am #

      To clarify, are you trying to execute a Python script from your terminal? If so you still need to use “workon” before executing the script (workon only needs to be executed once):

    • George October 1, 2017 at 1:05 pm #

      Same problem here, except i’m using Python 3.5.3. Did you find a solution ? Does anyone have a solution ?

  20. Syed Tauseef September 22, 2017 at 11:26 am #

    Hey Adrian Rosebrock ! Thanks for such a wonderful and simple tutorial, currently i am installing opencv (currently at installing numpy) i would like to know whether some of the open cv modules are dependent or matplotlib ? If so is it similar to installing like numpy ? with cv virtual environment “pip install matplotlib”

    • Adrian Rosebrock September 22, 2017 at 11:29 am #

      No, there are no OpenCV modules that are dependent on matplotlib. You can install it via:

      $ pip install matplotlib

      • Syed Tauseef September 23, 2017 at 5:02 am #

        Thanks ! I was successfully able to install open cv on my pi3 . At end you forgot to mention about deleting those zips (open cv and contrib ) file which might add few more mb of free space.

      • Syed Tauseef September 23, 2017 at 6:06 am #

        How do we access the environment variable in VNC or desktop terminal as” source ~/.profile “and” workon cv ” give invalid option . SSH i am able to get the cv environment.

        • Adrian Rosebrock September 23, 2017 at 9:59 am #

          Running:

          Will work over SSH, VNC, and terminal on the desktop.

          I’m not sure what error message you are getting, but again, the above commands will work just fine on all setups (provided there is not a misconfiguration, of course).

          • Syed Tauseef September 23, 2017 at 10:55 am #

            Yes ! Now i am able run these line without any errors fron VNC ,dont kown what was the reason for such error . Anyways thanks !

      • Niyazi Toker September 26, 2017 at 5:03 am #

        It does not worked for me. I took Memory Error, although I have memory.
        I tried “pip –no-cache-dir install matplotlib” command. Although I took again another error, at the end of I have installed matplotlib.

        • Adrian Rosebrock September 26, 2017 at 8:06 am #

          Correct, using:

          $ pip install matplotlib --no-cache-dir

          Will help if you are running into a MemoryError.

  21. Himanshu Singh September 26, 2017 at 6:49 am #

    Hi Adrian,

    I have followed your tutorial to install opencv3 using python3 in raspberri Pi3 stretch.

    I ran following commands:
    source ~/.profile
    workon cv
    python file_name.py

    error:

    Traceback (most recent call last):
    File “face_detection.py”, line 2, in
    importError : No module named ‘picamera’

    I tried to install ‘picamera’ using following commands:
    sudo apt-get update
    sudo apt-get install python3-picamera

    Result:

    python3-picamera is already installed the newest version (1.13)
    0 upgraded, 0 newly installed, 0 to remove and 20 not upgraded

    Again I tried to run:
    python file_name.py

    same importError :

    Traceback (most recent call last):
    File “face_detection.py”, line 2, in
    importError : No module named ‘picamera’

    I am not getting why this is happening. It’ll be very helpful if you can help me out of this.

    • Adrian Rosebrock September 26, 2017 at 8:06 am #

      You installed picamera via apt-get which will install it into your system install of Python, not the virtual environment. You should use:

      And you’ll be all set.

      • Himanshu Singh September 26, 2017 at 11:00 am #

        Thanks man! It’s working perfectly fine 🙂 🙂 _/\_

  22. James September 27, 2017 at 5:19 am #

    Really great instructions Adrian, thank you, saved me loads of time. However, i installed everything and found it used up 9.5GB of the sd card, so it might be worth mentioning that 16GB is recommend. I noticed on your setup it only took ~4.2GB. Is that after removing LibreOffice and Wolfram engine?

    • Adrian Rosebrock September 27, 2017 at 6:37 am #

      Correct, that is after removing LibreOffice and Wolfram Engine.

      • James September 27, 2017 at 2:28 pm #

        So worth mentioning if you use a 8GB sd card, you will need to remove LibreOffice and Wolfram Engine, otherwise when you try and build openCV you will most likely run out of space and get an error, then have to build it again, and this step can take hours so not something you want to happen.

  23. Bryan September 28, 2017 at 8:12 pm #

    when I try to download https://gethub.com/Itseez/opencv/archive/3.3.0.zip the connection just times out over and over

    • Adrian Rosebrock October 2, 2017 at 10:26 am #

      Hi Bryan — please double-check your internet connection and try again. There might have also been a problem with GitHub when you tried to download the code.

  24. arjun September 30, 2017 at 11:40 am #

    can openCV3.3 be installed in jessie

    • Adrian Rosebrock October 2, 2017 at 9:54 am #

      Yes, absolutely. I provide a number of OpenCV install tutorials for various Raspbian distributions here.

  25. Ace October 2, 2017 at 4:08 am #

    after expand the file system and reboot …
    i cant access to the raspberry pi through Remote Desktop.
    but able to use ssh access to the pi

    Anyone can help ?

    • Adrian Rosebrock October 2, 2017 at 9:25 am #

      Hmm, I don’t think this is an issue related to expanding the file system and rebooting. Can you ensure the remote desktop service is properly running?

  26. Banjo October 3, 2017 at 8:24 pm #

    Love the content, I wish I had snapped up the newest course at the early bird discount.

    If anyone waited 4 hours for compile, and without thinking pasted the “make clean” command. I feel your pain…from now on, read twice, paste once.

    Silver lining: I’ll never forget what make clean does.

    • Adrian Rosebrock October 4, 2017 at 12:35 pm #

      Ugh, I’m sorry to hear that Banjo. I’ll be posting an updated Raspberry Pi install tutorial this coming Monday, October 9th which will enable you to compile OpenCV on the Raspberry Pi in about 45 minutes.

  27. Sinan October 5, 2017 at 1:42 pm #

    Hi Adrian,
    When I reached the creation of virtual environment part, I accidently created another virtual part for Python 2.7 as well. But I want to work with Python 3.
    In Cmake output, both interpreter and numpy of Python 2.7 and Python 3 are located in the virtual environment cv.
    Will it cause any problem in the future?

    Thanks in advance

    • Adrian Rosebrock October 6, 2017 at 5:00 pm #

      Just to be safe I would suggest deleting both your Python virtual environment via the rmvirtualenv command and correctly creating your Python 3 one. From there, delete your “build” directory, re-create it, and re-run CMake.

  28. zet October 6, 2017 at 3:49 am #

    thank you

  29. Franco October 7, 2017 at 5:25 pm #

    Hello, thank you Adrian for this tutorial.
    I am having trouble at step 5:
    when I try the cmake -D……
    I get a bash: cmake: command not found.
    Any ideas why?

    • Adrian Rosebrock October 9, 2017 at 12:33 pm #

      Please make sure you “Step #2” where the “cmake” command is installed.

  30. Huy Nguyen October 7, 2017 at 11:26 pm #

    Hi Adrian,

    I followed the instructions and were able to install OpenCV 3.3.0 on my Raspberry Pi 3. Everything seemed to work pretty well until I ran into a Face Recognition Script that contained the following line:

    model = cv2.face.createEigenFaceRecognizer()

    The following Error Message was shown when I ran Python on it:

    “AttributeError: module ‘cv2’ has no attribute ‘face’ ”

    Everywhere I looked, the answer seemed to point to the “OpenCV’s extra modules” which I thought was already installed with opencv_contrib from the github.

    Any idea on how I can fix this?

    TIA,

    Huy –

    • Adrian Rosebrock October 9, 2017 at 12:32 pm #

      Indeed, it sounds like your install of OpenCV did not include the “opencv_contrib” modules. You will need to re-compile and re-install OpenCV.

  31. Leon October 8, 2017 at 12:26 am #

    Hi.
    the virtualenvironment is killing me.
    Unless I’m in it, I can’t see cv2 library.

    If I am in it, python can’t see picamera.array and other modules.

    This makes the home surveillance blog that was suggested to try opencv out impossible.

    time spent thus far: 10h compiling (even without make -j, it crashed at 83%, although power cycle -ie too hung to ssh into and stop cleanly) and 3h on this. Definitely not for the faint hearted!

    Is there an easy way to get needed modules into virtual environment? I have to abandon this soon – it is consuming too much time. A pity really, because I was hoping to bring it to my classroom.

    Cheers,
    Leon

    • Adrian Rosebrock October 9, 2017 at 12:31 pm #

      Hi Leon — that is the intended behavior of Python virtual environments. Python environments keep your system Python packages separate from your development ones. As far as your Pi crashing during the compile, take a look a this blog post which provides a solution. The gist is that you need to increase your swap space.

  32. Aaron October 8, 2017 at 2:12 pm #

    Will this tutorial work on a raspberry pi 2? Currently its os is raspian wheezy and from the offial website you can only download raspian stretch

    • Adrian Rosebrock October 9, 2017 at 12:21 pm #

      Hi Aaron — can you please clarify your comment? Are you running Raspbian Wheezy on your Pi and want to install OpenCV?

      • Aaron October 13, 2017 at 3:44 am #

        I have changed to Raspian Stretch but i have a Raspberry Pi 2 just wondering will this tutorial work for it as you are using a Raspberry Pi 3

        • Adrian Rosebrock October 13, 2017 at 8:35 am #

          I have not tested on the Raspberry Pi 2, but yes, this tutorial should work.

  33. Haseeb Ahmed October 10, 2017 at 6:36 am #

    Hi Adrian, i am using sift for features extratction. but it is showing that
    “module” has no attribute “xfeatures2d”. I have downloaded opencv_contrib and unzip it properly but still getting error when i run my code on raspberry pi 3.

    • Adrian Rosebrock October 13, 2017 at 9:10 am #

      Hi Haseeb — it sounds like your path to the opencv_contrib module during the CMake step was incorrect. Double-check the path, re-run CMake, and re-compile + re-install OpenCV.

  34. Bryan October 12, 2017 at 12:24 pm #

    Made it to the open CV compile
    stopped at 86%

    Spec ( Ras pi 0 wireless , stretch , python 2.7)

    should I attempt to change to python 3.0, reformat the sd card and start over, or attempt optimizing open CV and make -j4? useing your oct 9th article.

    Thanks

    • Adrian Rosebrock October 13, 2017 at 8:39 am #

      I would actually update your swap size, as I discuss in this post. From there, delete your “build” directory, re-create it, and re-compile.

  35. bob October 13, 2017 at 5:03 am #

    is there a way you can you run the Idle shell for python in the virtual environment

    • Adrian Rosebrock October 13, 2017 at 8:33 am #

      No, IDLE does not respect Python virtual environments. Please use the command line. If you like IDLE, try using Jupyter Notebooks that do work with Python virtual environments.

  36. Raju October 13, 2017 at 7:40 am #

    Hi,

    I am not able to import PIL from virtualenv. Can you please suggest how to fix the issue?

    Thanks in advance
    Raju

    • Adrian Rosebrock October 13, 2017 at 8:32 am #

      How did you install PIL? Did you install it into the Python virtual environment?

  37. Keith Glasnapp October 14, 2017 at 7:12 am #

    Why can’t your tutorial be run from a shell script? It would eliminate a lot of errors and retries?

    • Adrian Rosebrock October 14, 2017 at 10:30 am #

      It can be executed via a shell script in some situations; however, it’s also important to understand how the compile works, especially if you intend on optimizing your install. I also offer a pre-configured Raspbian .img file inside Practical Python and OpenCV.

  38. Terry October 14, 2017 at 11:28 am #

    Can this tutorial work on a 8GB card?

    • Adrian Rosebrock October 16, 2017 at 12:34 pm #

      If you purge Wolfram Alpha and LibreOffice you should be okay, but I would really suggest using a 16GB card.

  39. rich October 15, 2017 at 8:51 pm #

    Oh man. I found this link for stretch. It seems to work because everything went smoothly untill I try to compile opencv. At this step cd ~/opencv-3.3.0/ it tells me that the directory does’t exist.

    So I mkdir one then mkdir build, cd into build. when try to compile, it tells me it doesn’t contain CMakeLists.txt , where is this CMakeLists.txt ?

    • Adrian Rosebrock October 16, 2017 at 12:22 pm #

      Hi Rich — it’s hard to say what the exact issue is without seeing the directory structure of your project. Can you ensure that OpenCV was properly downloaded and unzipped in your home directory?

  40. Daniel October 16, 2017 at 2:13 am #

    I’m very new to this and I just followed your video and now I have it downloaded so thank you. However, I don’t know what to do know, like how to write and run scripts in this virtual environment because every time I type python into it, the shell pops up. Could someone tell me how to open blank scripts so I can start writing code. Thank you

    • Adrian Rosebrock October 16, 2017 at 12:20 pm #

      Hey Daniel — you would need to supply the path to the Python script you would like to execute:

      $ python your_script.py

      Open up the a file in your favorite plaintext editor, save it as a .py file, and insert your code. From there execute it via the command line.

  41. Marc October 16, 2017 at 10:54 am #

    Could add “nohup” to long-running commands? It’s not unusual to lose the ssh connection and it gets frustrating as the installation is pretty long already.

    • Adrian Rosebrock October 16, 2017 at 12:14 pm #

      You could absolutely use “nohop”; however, I prefer using “screen”.

  42. Scott October 17, 2017 at 12:24 pm #

    In step 5, after cmake completes I type ‘make’ but there are no Makefiles that it can run against.

    • Adrian Rosebrock October 19, 2017 at 5:02 pm #

      Please check your output of “CMake” as it likely returned an error (and thus no Makefiles were generated).

  43. olivia October 19, 2017 at 12:09 am #

    Hello adrian,
    thank you. this is the best tutorial i ever seen.
    but i got one problem
    when i’m run this script

    $ ls -l /usr/local/lib/python2.7/site-packages/

    i just get 300+ (3 digit) even though you get 1852

    and then i’m
    $ ls -l /usr/local/lib/python3.5/site-packages/
    i got 3500+ (4 digit) and you got 1852

    please help me adrian to fix this, thank you

    • Adrian Rosebrock October 19, 2017 at 12:20 pm #

      Hi Olivia — thanks for the comment. That number will depend upon the packages you have installed in your environment.

      • olivia October 29, 2017 at 9:07 am #

        i just follow your step adrian, why i get that value? is that ok for my next step when i want to using python?

        • Adrian Rosebrock October 30, 2017 at 2:58 pm #

          I think it is safe to carry on with the instructions. Don’t worry about these values.

          • olivia November 2, 2017 at 2:44 am #

            ok.. thank you adrian

  44. Akash October 19, 2017 at 3:44 am #

    Hello Adrian,
    I have installed the opencv inside the virtual environment ,
    but i’m unable to access outside (i.e)., Inside the IDLE.
    How to access it.

    • Adrian Rosebrock October 19, 2017 at 8:36 am #

      Hi Akash — thanks for the comment. Unfortunately, IDLE cannot access Python virtual environments. I would suggest using Jupyter Notebooks which do work with Python virtual environments.

  45. Cahit October 21, 2017 at 11:11 pm #

    Hello Adrian. I just wanted to say thanks. It took a long time but it was a problem-free installation. Nice guide.

    • Adrian Rosebrock October 22, 2017 at 8:24 am #

      Congrats on getting OpenCV installed, nice job!

  46. Enzo October 23, 2017 at 1:37 pm #

    Hi Adrian, great walkthrough, tutorial or wathever you want to call it, made it without any trouble in the times that are say… although this only work as long as someone work on the virtual environment, is there any way to make this work outside the virtual env. to use opencv on python directly??

    Thanks for everything mate, cheers.

    • Adrian Rosebrock October 23, 2017 at 5:15 pm #

      Hi Enzo — it’s a best practice to use Python virtual environments. Each Python virtual environment copies the binaries and libraries of your system Python but doesn’t keep any existing installed libraries. Therefore, you can use OpenCV + Python directly. If you do not want to use Python virtual environments you can either (1) follow the steps and ignore virtualen/virtualenvwrapper steps or (2) sym-link any packages into your system install of Python.

  47. mory October 23, 2017 at 4:55 pm #

    hi
    i do everything in this tutorial but in step #5 when compiling opencv it freeze up at 86%….
    i use $ make clean $ make
    but freeze up again at 86%
    .what can i do??? please help me….please help me…please (:

    • Adrian Rosebrock October 23, 2017 at 5:19 pm #

      It sounds like you might be running out of swap space. Please see this tutorial on how to increase your swap.

  48. mory October 23, 2017 at 5:00 pm #

    is there a respbian stretch image that opencv and python have been installed on it??? and i just write this on my sd card and use…. is this possible????

    • Adrian Rosebrock October 23, 2017 at 5:17 pm #

      Hi Mory — I would suggest you take a look at the Quickstart Bundle and Hardcopy Bundle of Practical Python and OpenCV. Both these bundles include a pre-configured Raspbian .img file with OpenCV pre-installed.

      • Mory October 24, 2017 at 2:04 am #

        thank you very much Adrian..

  49. Devaraju October 24, 2017 at 1:48 am #

    Hi,
    I’m getting following error after CMake it says “Configuration incomplete, errors occurred!”

    • Adrian Rosebrock October 24, 2017 at 7:12 am #

      Please check the output of CMake — it will report what the specific error is and why the command failed.

  50. Shane October 25, 2017 at 5:37 pm #

    Great tutorial… Is there a way to install SimpleCV on top of this? I’ve tried, but keep getting memory errors. Thanks Adrian..

  51. GIBIN October 27, 2017 at 9:01 am #

    I had completed installing the opencv to 100%. But when I check it using the code below

    source ~/.profile
    $ workon cv
    $ python
    >>> import cv2
    it is showing errors that the file is not created or something like that

    • Adrian Rosebrock October 27, 2017 at 11:50 am #

      Make sure you’ve properly linked cv2.so to your virtual environment. See Step #6.

  52. Eyal October 27, 2017 at 11:26 pm #

    Hello Adrian,
    do you have a similar guide to install scikit-learn on a pi as well?
    Thanks

    • Adrian Rosebrock October 30, 2017 at 2:17 pm #

      The easiest way is via PIP in your virtual environment: pip install -U scikit-learn

  53. Suzanna October 28, 2017 at 12:23 pm #

    Hi Adrian,
    I have tried to follow these steps multiple times now, but at step I keep getting a wrong output from the cmake. The library, numpy and packages paths are missing. Do you know what I could be doing wrong?
    Kind regards,
    Suzanna

    • Adrian Rosebrock October 30, 2017 at 2:41 pm #

      Hi Suzannna — perhaps you aren’t inside your virtual environment when you issued the CMake command.

  54. Don October 28, 2017 at 8:25 pm #

    Adrian, I followed, I believe all the instructions up to the actual compile where the last thing is type in ‘make’ and it should start compiling. What I get is an error message >> make: *** No targets specified and no makefile found. stop.
    What did I miss doing?

    • Adrian Rosebrock October 31, 2017 at 8:02 am #

      Hey Don — try double-checking your output of CMake. It sounds like the “cmake” command exited with an error. Check the terminal output and you should be able to spot what threw the error.

  55. Raghuram October 29, 2017 at 2:43 pm #

    when i enter make this comes up:
    (cv) pi@raspberrypi:~/opencv-3.3.0/build $ make
    make: *** No targets specified and no makefile found. Stop.

    • Adrian Rosebrock October 30, 2017 at 2:46 pm #

      Hi Raghuram, did you first use CMake which will generate the Makefile?

      • Raghuram October 31, 2017 at 1:56 pm #

        I started the process again and now it shows an error at 86% ,that says boostdec_bgm.i missing.
        thanks for the reply please help me ou

        • Raghuram November 1, 2017 at 11:56 pm #

          I was able to install it but could and import cv2 worked on terminal , but it could not work in python please help!!

          • Adrian Rosebrock November 2, 2017 at 2:16 pm #

            Hey Raghuram — I’m not sure what you mean by you could import the cv2 library in your terminal but not in Python. Could you please elaborate? Are you trying to use Python IDLE? Keep in mind that Python IDLE does not respect Python virtual environments.

  56. olivia November 1, 2017 at 6:18 am #

    Adrian, i wanna restart my raspberry from zero. i have install following your step and now i want deleting all and start from zero.. how to do that?

    • Adrian Rosebrock November 2, 2017 at 2:30 pm #

      If you want to start completely from scratch I would recommend re-flashing Raspbian onto your SD card. If you want to restart your OpenCV compile just delete your “build” directory and recreate it.

  57. santiago g November 1, 2017 at 4:58 pm #

    help!. in the step of executing cmake I have a problem only appear the directories for python 3 and not for python 2.7 I tried many times updating my profile and even repeat from the beginning the procedure and do not appear please could help me

    • Adrian Rosebrock November 2, 2017 at 2:19 pm #

      You can only compile OpenCV bindings for ONE Python version at a time. If you have the correct directories for Python 3 then you can proceed with the compile to obtain your Python 3 + OpenCV bindings.

  58. Raghuram November 1, 2017 at 10:58 pm #

    ln: failed to create symbolic link what do i do for this kind of error

  59. Ivan Chuang November 2, 2017 at 12:41 pm #

    Dear Adrian,
    In step #5 , I am sure I am in the cv virtual env. — “(cv) pi@raspberrypi:~/opencv-3.3.1/build $ “.

    But when I type “cmake -D CMAKE_BUILD_TYPE=RELEASE \…..”. I got a error message –“CMake Error: The source directory “/home/pi/opencv-3.3.1/build/CMAKE_BUILD_TYPE=RELEASE” does not exist.”.

    Yours faithfully
    Ivan Chuang

    • Ivan Chuang November 2, 2017 at 1:22 pm #

      HI Adrian,
      I got the answer, just like this “cmake -DCMAKE_BUILD_TYPE=RELEASE \”.

      But I have another question. When I want to make sure my Python3 section, I don’t know I need to check which file.

      Yours faithfully
      Ivan Chuang

      • Adrian Rosebrock November 2, 2017 at 2:06 pm #

        Congrats on resolving the CMake issue. As for checking your “Python 3” section just scroll up in your terminal and examine the output of the “cmake” command.

  60. CESAR November 2, 2017 at 5:29 pm #

    There is no sudo make install
    I get it, “not exitis file install”

    HELP !!!!

    • Adrian Rosebrock November 6, 2017 at 10:53 am #

      I would suggest checking the output of CMake. It sounds like the “cmake” command exited with an error and did not create the Makefile.

  61. Shiv Trivedi November 5, 2017 at 4:11 pm #

    Hi Adrian,
    I’ve been following a lot of your blog posts and tutorials, and I find them amazing! Thank you so much for this amazing and super easy to follow guide to setting up OpenCV 3 on the new Raspbian Stretch!

    Big Fan,
    Shiv

    • Adrian Rosebrock November 6, 2017 at 10:34 am #

      Thank you for the comment, Shiv! And congrats on getting OpenCV installed on your Raspberry Pi!

  62. jad November 5, 2017 at 4:23 pm #

    that was really helpful .
    thank you very much for your help .
    i did the make command when i was in the env .
    and it worked just fine and finished successfully
    when i did sudo make install
    it is taking me the same time that “make” did. (that sentence makes no sense 😛 )
    is it normal ?

    • Adrian Rosebrock November 6, 2017 at 10:34 am #

      Hi Jad — as long as the command executes without error you should be okay.

  63. Colin November 6, 2017 at 4:08 pm #

    Hi Adrian
    I have compiled OpenCV3 on a fresh version of Rasbian Stretch following your recipe, (although I did not use a virtual environment).
    I am using a Python script that was developed in Jessie and OpenCV 2.4.9 and have updated the syntax where necessary. Everything seems to be successful apart from one thing, cv2.resize() and cv2.resizeWindow()are not working. They do not throw an error but have no effect on the size of the image or the window (I am using cv2.WINDOW_NORMAL). Is there anything obvious that I may have missed?
    Thanks
    Colin

    • Adrian Rosebrock November 6, 2017 at 4:26 pm #

      I’m not sure about cv2.resizeWindow as I’ve never used that function before but to check cv2.resize print the resulting .shape to your terminal. If that’s not your expected dimensions then there is likely a logic error somewhere else in the code.

  64. Ronald November 7, 2017 at 11:13 pm #

    Hello Adrian

    I enjoyed this tutorial. The most advanced project I’ve ever attempted but its not complete. I reached the total “1852”

    I got to step 7 and entered “workon cv” and got command not found

    To my horror I suspect I forgot, yes the sym-link step. Can’t get in the cv environment.

    Help!! Thanks

    Ronald

    • Adrian Rosebrock November 9, 2017 at 6:45 am #

      Hey Ronald, I would suggest going back to Step 4 and ensure you have updated your .profile file. I would also suggest ensuring virtualenv/virtualenvwrapper have been properly installed.

  65. Jonathan Thompson November 8, 2017 at 1:02 pm #

    Hello Adrian I’m also having an issue with the “make” command,

    I’ve followed the previous step with the “cmake” command successful and when i “ls” in the “build” directory the make files are there but when i use the “make” command it says:

    make: *** No targets specified and no makefile found. Stop.

    Its defiantly in the (cv) environment also.

    any suggestions would be much appreciated,

    Kind regards,

    Jonathan

    • Adrian Rosebrock November 9, 2017 at 6:21 am #

      Please see my reply to “Don” and “Raghuram”.

  66. Jehl November 12, 2017 at 4:47 am #

    On my Pi no problem to compile with make -j4. But, I have added blas and lapack with :
    sudo apt-get install libblas-dev liblapack-dev

  67. Julien November 13, 2017 at 3:25 am #

    Please you used the full or lite version for Raspbian ?

    • Adrian Rosebrock November 13, 2017 at 1:57 pm #

      I used the full version of Raspbian but you can use the lite version as well.

  68. Sarthak November 13, 2017 at 12:29 pm #

    Hello Adrian I’m also having an issue with the “make” command,
    the compilation stops at 30% i even tried to increase the swap size to 1024
    and compiling using make -j4 but still it does not compile more than 30%

    • Adrian Rosebrock November 13, 2017 at 1:53 pm #

      Hi Sarthak — try using only a single core via make. The compile will take longer but provided you increased your swap it should work.

      • Sarthak November 14, 2017 at 1:08 am #

        I did the make but did not increase the swap size just used make not make -j4 but the complilation stopped at 89%
        Will increase the swap size help in this?

        • Adrian Rosebrock November 15, 2017 at 1:06 pm #

          Yes. Increasing the swap size should resolve this issue completely.

  69. Sakshi Patel November 19, 2017 at 9:12 am #

    I have installed opencv 3 as explained above and followed all the steps for python 3
    When i am running a program of face recognition data set in python IDE 3 it is giving error in the line import cv2
    Importerror: No module named “cv2”
    Plz help me to solve this

    • Adrian Rosebrock November 20, 2017 at 3:59 pm #

      Please see my reply to “Hidenori Kaga”, “bob”, “Akash”, and others. I have addressed this question multiple times.

  70. 冰河 November 20, 2017 at 1:38 am #

    Hello Adrian.
    sudo apt-get update
    sudo apt-get upgrade
    sudo apt-get install libopencv-dev
    sudo apt-get install python-opencv
    Is this ok? install opencv

    • Adrian Rosebrock November 20, 2017 at 3:52 pm #

      I DO NOT recommend this method. The apt-get package definitions are often out of date and you won’t have the additional extra modules with OpenCV. I highly encourage you to compile OpenCV from source, using apt-get is not recommended.

  71. Cirkp November 20, 2017 at 6:34 pm #

    Hello Adrian,

    I followed this tutorial and everything went well to step 5.
    After the command cmake I get an instant error: “segmention fault” and i can’t go on.

    Could you help me?

    • Adrian Rosebrock November 21, 2017 at 1:26 pm #

      The “cmake” command caused a segmentation fault? That’s not good. It sounds like something might be wrong with your Raspberry Pi/Raspbian. Could you re-install Raspbian then try again? Unfortunately I’m not sure what the exact problem is here.

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