Today’s blog post on reading barcodes and QR codes with OpenCV is inspired by a question I received from PyImageSearch reader, Hewitt:
Hey Adrian, I really love the PyImageSearch blog. I look forward to your emails each week. Keep doing what you’re doing.
I have a question for you:
Does OpenCV have any modules that can be used to read barcodes or QR codes? Or do I need to use an entirely separate library?
Thanks Adrian.
Great question, Hewitt.
The short answer is no, OpenCV does not have any dedicated modules that can be used to read and decode barcodes and QR codes.
However, what OpenCV can do is facilitate the process of reading barcodes and QR codes, including loading an image from disk, grabbing a new frame from a video stream, and processing it.
Once we have the image or frame we can then pass it to a dedicated Python barcode decoding library such as a Zbar.
The ZBar library will then decode the barcode or QR code. OpenCV can come back in to perform any further processing and display the result.
If this sounds like a complicated process, it’s actually pretty straightforward. The ZBar library, along with its various forks and variations, have come a long way. One set of ZBar bindings in particular, pyzbar , is my personal favorite.
Inside today’s tutorial, I will show you how to read barcodes and QR codes with OpenCV and ZBar.
And as an added bonus, I’ll demonstrate how to deploy our barcode scanner to the Raspberry Pi as well!
To learn more about reading barcodes and QR codes with OpenCV and ZBar, just keep reading.
An OpenCV barcode and QR code scanner with ZBar
Today’s blog post is broken into four parts.
In the first part, I’ll show you how to install the ZBar library (with Python bindings).
The ZBar library will be used together with OpenCV to scan and decode barcodes and QR codes.
Once ZBar and OpenCV are properly configured I’ll demonstrate how to scan barcodes and QR codes in a single image.
Starting with a single image will give us the practice we need to prepare for the next step: Reading barcodes and QR codes in real-time with OpenCV and ZBar,
Finally, I’ll demonstrate how to deploy our real-time barcode scanner to the Raspberry Pi.
Installing ZBar (with Python bindings) for barcode decoding
A few weeks ago Satya Mallick from the LearnOpenCV blog posted a really great tutorial on using the ZBar library to scan barcodes.
The instructions to install ZBar in today’s post are largely based on his instructions, but with a few updates, the largest one being related to how we install the Python zbar bindings themselves, ensuring we can:
- Use Python 3 (the official
zbarPython bindings only support Python 2.7) - Detect and localize exactly where in the image the barcode is.
Installing the necessary software is an easy 3-step process.
Step 1: Install zbar from the apt or brew repository
Installing ZBar for Ubuntu or Raspbian
Installing ZBar for Ubuntu can be accomplished with the following command:
$ sudo apt-get install libzbar0
Installing ZBar for macOS
Installing ZBar for macOS using brew is equally as easy (assuming you have Homebrew installed):
$ brew install zbar
Step 2 (Optional): Create a virtual environment and install OpenCV
You have two options here:
- Use an existing virtual environment that has OpenCV ready to go (skip this step and head to Step 3).
- Or create a new, isolated virtual environment which involves installing OpenCV.
Virtual environments are a best practice for Python development and I highly encourage you to make use of them.
I elected to create a new, isolated Python 3 virtual environment and followed the Ubuntu (or macOS, depending on which machine I was using) OpenCV installation instructions linked on this page. The only change I made while following those instructions was to name my environment barcode :
$ mkvirtualenv barcode -p python3
Note: If you already have OpenCV installed on your system you can skip the OpenCV compile process and simply sym-link your cv2.so bindings into the site-packages directory of your new Python virtual environment.
Step 3: Install pyzbar
Now that I have a Python 3 virtual environment named barcode on my machine, I activated the barcode environment (yours might have a different name) and installed pyzbar :
$ workon barcode $ pip install pyzbar
If you are not using a Python virtual environment you can just do:
$ pip install pyzbar
If you’re trying to install pyzbar into the system version of Python make sure you use the sudo command as well.
Decoding barcodes and QR codes with OpenCV in single images
Before we implement real-time barcode and QR code reading, let’s first start with a single image scanner to get our feet wet.
Open up a new file, name it barcode_scanner_image.py and insert the following code:
# import the necessary packages
from pyzbar import pyzbar
import argparse
import cv2
# construct the argument parser and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-i", "--image", required=True,
help="path to input image")
args = vars(ap.parse_args())
On Lines 2-4 we import our required packages.
Both pyzbar and cv2 (OpenCV) need to be installed following the instructions in the previous section.
In contrast, argparse is included with the Python install and it is responsible for parsing command line arguments.
We have one required command line argument for this script (--image ) and it is parsed on Lines 7-10.
You’ll see at the end of this section how to run the script while passing a command line argument containing the input image path.
Now, let’s take the input image and put pyzbar to work:
# load the input image image = cv2.imread(args["image"]) # find the barcodes in the image and decode each of the barcodes barcodes = pyzbar.decode(image)
On Line 13, we load the input image via its path (contained in our convenient args dictionary).
From there, we call pyzbar.decode to find and decode the barcodes in the image (Line 16). This is where all the magic of ZBar happens.
We aren’t finished yet — now we need to parse the information contained within the barcodes variable:
# loop over the detected barcodes
for barcode in barcodes:
# extract the bounding box location of the barcode and draw the
# bounding box surrounding the barcode on the image
(x, y, w, h) = barcode.rect
cv2.rectangle(image, (x, y), (x + w, y + h), (0, 0, 255), 2)
# the barcode data is a bytes object so if we want to draw it on
# our output image we need to convert it to a string first
barcodeData = barcode.data.decode("utf-8")
barcodeType = barcode.type
# draw the barcode data and barcode type on the image
text = "{} ({})".format(barcodeData, barcodeType)
cv2.putText(image, text, (x, y - 10), cv2.FONT_HERSHEY_SIMPLEX,
0.5, (0, 0, 255), 2)
# print the barcode type and data to the terminal
print("[INFO] Found {} barcode: {}".format(barcodeType, barcodeData))
# show the output image
cv2.imshow("Image", image)
cv2.waitKey(0)
Beginning on Line 19, we loop over the detected barcodes .
In this loop, we proceed to:
- Extracting the bounding box (x, y)-coordinates from the
barcode.rectobject (Line 22), enabling us to localize and determine where in the input image the current barcode is. - Draw draw a bounding box rectangle on the
imagearound the detectedbarcode(Line 23). - Decode the
barcodeinto a"utf-8"string and extract the type of barcode (Lines 27 and 28). It is critical to call the.decode("utf-8")function on the object to convert from a byte array to a string. You can experiment by removing/commenting it out to see what happens — I’ll leave this as an experiment for you to try. - Format and draw the
barcodeDataandbarcodeTypeon the image (Lines 31-33). - And finally, output the same data and type information to the terminal for debugging purposes (Line 36).
Let’s test our OpenCV barcode scanner. You should use the “Downloads” section at the bottom of this blog post to download the code and example image.
From there, open up your terminal and execute this command:
$ python barcode_scanner_image.py --image barcode_example.png
[INFO] Found QRCODE barcode: {"author": "Adrian", "site": "PyImageSearch"}
[INFO] Found QRCODE barcode: https://hcl.pyimagesearch.com/
[INFO] Found QRCODE barcode: PyImageSearch
[INFO] Found CODE128 barcode: AdrianRosebrock
As you can see in the terminal, all four of the barcodes were found and properly decoded!
Refer to Figure 1 for the processed image which has overlaid red rectangles and text for each barcode our software found.
Real-time barcode and QR code reading with OpenCV
In the previous section, we learned how to create a Python + OpenCV barcode scanner for single images.
Our barcode and QR code scanner worked well — but it raises the question, can we detect and decode barcode + QR codes in real-time?
To find out, open up a new file, name it barcode_scanner_video.py , and insert the following code:
# import the necessary packages
from imutils.video import VideoStream
from pyzbar import pyzbar
import argparse
import datetime
import imutils
import time
import cv2
# construct the argument parser and parse the arguments
ap = argparse.ArgumentParser()
ap.add_argument("-o", "--output", type=str, default="barcodes.csv",
help="path to output CSV file containing barcodes")
args = vars(ap.parse_args())
On Lines 2-8 we import our required packages.
At this point, recalling the above explanation, you should recognize pyzbar , argparse , and cv2 .
We’ll also use VideoStream to handle capturing video frames in an efficient, threaded approach. You can learn more about the VideoStream class here. And if you do not have imutils installed on your system, just use the following command:
$ pip install imutils
We’re going to parse one optional command line argument, --output , which contains the path to the output Comma Separated Values (CSV) file. This file will contain the timestamp and payload of each detected and decoded barcode from our video stream. If this argument isn’t specified, the CSV file will be placed in our current working directory with a name of "barcodes.csv" (Lines 11-14).
From there, let’s initialize our video stream and open our CSV file:
# initialize the video stream and allow the camera sensor to warm up
print("[INFO] starting video stream...")
# vs = VideoStream(src=0).start()
vs = VideoStream(usePiCamera=True).start()
time.sleep(2.0)
# open the output CSV file for writing and initialize the set of
# barcodes found thus far
csv = open(args["output"], "w")
found = set()
On Lines 18 and 19 we initialize and start our VideoStream . You may either:
- Use your USB webcam (uncomment Line 18 and comment Line 19)
- Or if you’re using a Raspberry Pi (like me) you can use the PiCamera (uncomment Line 19 and comment Line 18).
I chose to use my Raspberry Pi PiCamera, as is shown in the next section.
We then pause for two seconds to allow the camera can warm up (Line 20).
We’ll be writing all barcodes we find to disk in a CSV file (but ensuring duplicates are not written). This is meant to be a (trivial) example of logging barcodes. You could, of course, do whatever you want once a barcode is detected and read such as:
- Save it in a SQL database
- Send it to a server
- Upload it to the cloud
- Send an email or text message
The actual action is arbitrary — we’re simply using the CSV file as an example.
Feel free to update the code to include any notification you may wish.
We open the csv file for writing on Line 24. If you are modifying the code to append to the file, you can simply change the 2nd parameter from "w" to "a" (but you’ll have to search the file for duplicates in a different way).
We also initialize a set for found barcodes. This set will contain unique barcodes while preventing duplicates.
Let’s begin capturing + processing frames:
# loop over the frames from the video stream while True: # grab the frame from the threaded video stream and resize it to # have a maximum width of 400 pixels frame = vs.read() frame = imutils.resize(frame, width=400) # find the barcodes in the frame and decode each of the barcodes barcodes = pyzbar.decode(frame)
On Line 28 we start our loop and proceed to grab and and resize a frame from our video stream (Lines 31 and 32).
From there, we call pyzbar.decode to detect and decode any QR + barcodes in the frame .
Let’s proceed to loop over the detected barcodes :
# loop over the detected barcodes
for barcode in barcodes:
# extract the bounding box location of the barcode and draw
# the bounding box surrounding the barcode on the image
(x, y, w, h) = barcode.rect
cv2.rectangle(frame, (x, y), (x + w, y + h), (0, 0, 255), 2)
# the barcode data is a bytes object so if we want to draw it
# on our output image we need to convert it to a string first
barcodeData = barcode.data.decode("utf-8")
barcodeType = barcode.type
# draw the barcode data and barcode type on the image
text = "{} ({})".format(barcodeData, barcodeType)
cv2.putText(frame, text, (x, y - 10),
cv2.FONT_HERSHEY_SIMPLEX, 0.5, (0, 0, 255), 2)
# if the barcode text is currently not in our CSV file, write
# the timestamp + barcode to disk and update the set
if barcodeData not in found:
csv.write("{},{}\n".format(datetime.datetime.now(),
barcodeData))
csv.flush()
found.add(barcodeData)
This loop should look very familiar if you read the previous section.
In fact, Lines 38-52 are identical to those the single image script. Please refer to the single image barcode detection and scanning section for a detailed review of this code block.
Lines 56-60 are new. On these lines, we check if we’ve found a unique (not previously found) barcode (Line 56).
If that’s the case, we write the timestamp and data to the csv file (Lines 57-59). We also append the barcodeData to a found set as a simple way to handle duplicates.
In the remaining lines of the real-time barcode scanner script, we display the frame, check if the quit key is pressed, and perform cleanup:
# show the output frame
cv2.imshow("Barcode Scanner", frame)
key = cv2.waitKey(1) & 0xFF
# if the `q` key was pressed, break from the loop
if key == ord("q"):
break
# close the output CSV file do a bit of cleanup
print("[INFO] cleaning up...")
csv.close()
cv2.destroyAllWindows()
vs.stop()
On Line 63 we display the output frame .
Then on Lines 64-68, we check for keys and if "q" is pressed, we break out of the main execution loop.
Finally, we perform cleanup on Lines 72-74.
Building a barcode and QR code scanner on the Raspberry Pi
What fun is a barcode scanner if I’m limited to my desk?
I decided that I’d like to take my barcode scanner with me using my Pi, touchscreen, and battery pack.
Shown in Figure 2 is my setup — the exact one I used for my mobile Pokedex deep learning project recently. If you’re looking to build your own with the exact peripherals shown, I’ve listed the products and links:
- Raspberry Pi 3 (or you could use the latest 3 B+)
- Raspberry Pi camera module
- Pi Foundation 7″ touchscreen display
- Portable Charger RAVPower 22000mAh Power Bank
Building the system is really easy and I’ve made step-by-step instructions in this blog post.
Once your mobile ZBar barcode scanner is ready, use the “Downloads” section of this blog post to download the code associated with this blog post.
From there, open up a terminal on your Pi and launch the app with the following command (you’ll need a keyboard/mouse for this step but then you can disconnect and let the app run):
$ python barcode_scanner_video.py [INFO] starting video stream...
Now you can present barcodes to the camera and when you’re done, you can open the barcodes.csv file (or if you’re so inclined you can execute tail -f barcodes.csv in a separate terminal to view the data as it enters the CSV file live).
The first QR code that I tried is shown on a black background — it is very easy for ZBar to detect:
Then I headed to my kitchen, with Pi, screen, and battery pack in hand, and found another QR code:
Success! It even works at many angles.
Now let’s try a QR code that is contains a JSON-blob of data:
No match for my OpenCV + ZBar + Python barcode scanner project!
And finally, I tried a traditional 1-D barcode:
1-D barcodes are slightly more challenging for the system especially with a PiCamera which doesn’t support autofocus. That being said, I achieved a successful detection and decoding of this barcode as well.
You might have best luck with a USB webcam such as the Logitech C920 which has great autofocus. Alternatively, you can actually change the factory focus on your PiCamera using the method that Jeff Geerling describes on his blog.
That’s a wrap!
If you’re interested in reading additional barcode blog posts on my website, check out the posts with the “barcode” tag.
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Summary
In today’s blog post you learned how to build an OpenCV barcode and QR code scanner.
To accomplish this, we used the ZBar library.
Once the ZBar library was installed on our system, we created two Python scripts:
- The first one to scan barcodes and QR codes in a single image
- And a second script to read barcodes and QR codes in real-time
In both cases, we used OpenCV to facilitate the process of building our barcode/QR code scanner.
Finally, we wrapped up today’s blog post by deploying our barcode reader to the Raspberry Pi.
The barcode scanner is fast enough to run in real-time on the Raspberry Pi without an issue.
Feel free to use this barcode and QR code scanner functionality in your own projects!
And if you build something fun and interesting with it, be sure to share your project in the comments.
I hope you enjoyed today’s post. I’ll see you next week.
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Hey Adrian, you have written this following note:
” If you already have OpenCV installed on your system you can skip the OpenCV compile process and simply sym-link your cv2.so bindings into the site-packages directory of your new Python virtual environment”.
Here you have mentioned to symlink the cv2.so file with site packages …How to do it? Can you please elaborate on that?
Thank you
Hey Nachiket — are you using a Python virtual environment? And did you follow one of my tutorials here on PyImageSearch to install OpenCV? Provided you used one of my tutorials, select the relevant one, and then follow the sym-link steps.
Yes sir I have always followed your tutorials on creating virtual environment but I couldn’t find the symlink steps. I have recently followed the rpi stretch OS installation on Rpi, are symlink steps are involved there?
If you are struggling with the process I would just recommend installing the ZBar into your current Python virtual environment.
Great post.
I actually open the url with webbrowser
Now – It will be great to port it to my phone (Android)
Thanks Gilad, I’m glad you enjoyed the post and found it helpful 🙂
Hi Adrian,
It is interesting. You are increasing my hope to continue my research in the field of IoT. Waiting for more posts.
Thank you.
Suganya
Thank you for the kind words, Suganya 🙂
Hello I am very interested in your work on opencv and python. Currently I am working on a project using opencv and python. I have questions of understanding to ask you. Can you send me your email address or directly reply to my email address: EMAIL ADDRESS REMOVED. Thank you Best regards
Please do not share your email address directly within a comment. You can contact me via the PyImageSearch contact form.
Hi, first thank you very much for your excellent tutorial, super clear and complete as usual.
2 quick questions:
1. How many fps do you achieve on the rpi3?
2. Why do you always resize to 400px in your tutorial through opencv, especially for video stream? You could setup the frame size h x w at camera init stage at it would save a costly opencv resize at each frame no? (Assuming the sizing is done by the camera, not the video driver)
Thanks
Tets
1. I did not compute the raw FPS but the barcode detector was easily running in real-time on the Raspberry Pi 3.
2. You could certainly do that as well; however, you should be careful when doing it. There are times were you might want to display the full size output frame but process a smaller version of the frame for efficiency/accuracy. A great example would be processing all frames in a video file and writing them back to disk. It’s a use case decision to be mindful of.
Hi Adrian, first of all thanks for this great tutorial!
I have a couple questions on how I can further improve the system.
I tried running the python file with some images of my own (of objects with QR codes on it) but it would not detect the QR codes at all.
Is this because of noise? Or could it be that the size of the QR code in respect to the image overall is too small?
I have also tried to run it with a resized and enlarged photo, but it does not seem to work and I’m not sure what next steps I should be taking and would like some advice.
Thanks
k
This could happen for many reasons, including noise, the QR code being too small, or an issue with your camera sensor. Unfortunately I’m not sure what the issue would be without seeing an example image of what you’re working with.
Hi Adrian, thank you for your great tutorials! For a running project I tried to combine some of your blog posts. I would like to detect DataMatrix Codes in an Image or Video-Stream.
Unfortunately ZBAR does not Support Datamatrix Codes. I tried pylibdmtx (https://github.com/NaturalHistoryMuseum/pylibdmtx ) and it works fine for perfect separated and aligned Codes but (of course) not for detection within an image or video.
I gave OpenMV a chance but the result was very slow an not suitable for small Codes because of the low resolution of the camera.
Based on your blog post („Detecting Barcodes in Images with Python and OpenCV“) I also tried to detect the DataMatrix Code with OpenCV. Its perfect for 1D-Barcodes but it failed in detecting 2D-Barcodes…
Can you give me a hint, how to detect DataMatrix Codes in OpenCV?
Thank you & Best regards
It sounds like you may want to continue working with the pylibdmtx library for the project. I don’t have any experience with that particular library but if you’re having issues detecting/reading the DataMatrix codes you may want to try cleaning up the image and extracting just the barcode before you try to pass it into the library.
Hi I have come up with the same problem. If you have solved, can you point me to the right direction to be able to read data matrix in real time? or provide me with the solution?
Hi Adrian,
thanks for this tutorial. I did some experiments: the software recognizes correctly the bar code only if it’s very close to the camera (2/3 inches).
It will be great to implement an object recognition for bar code images in a frame, crop the rect and pass it to pyzlib.
Using a HiRes camera (FullHD) it would be possible to increase the results.
What do you think about it?
You could do this but you would need to train your own custom object detector. HOG + Linear SVM would be a good start. You may want to take a look at deep learning object detectors as well.
thanks for the tutorial. I was trying real time barcode scanning using a web cam, since the pi camera have fixed focus. can u give me a link or your own work on barcode scanning using web cam. It would be a great help
The code in this blog post already works with a webcam. See Lines 18 and 19 of the
barcode_scanner_video.pyscript.oh yeah, thanks for the great tutorial
hi adrian,
ive followed each step you taught, but im getting :
from pyzbar import pyzbar
ImportError: No module name pyzbar
You need to install the pyzbar library as instructed in the post:
$ pip install pyzbarIf you are using a Python virtual environment make sure you access it when you install pyzbar and when you run the code.
thanks..
hi, im getting error:
ImportError : no module named imutils.video
but, ive already uninstalled and installing it again by using ‘sudo pip3 install –upgrade imutis’
ive also imported imutils.video in python and not getting error
so why did the importError happened?
Are you using a Python virtual environment? If so, you can’t use “sudo” as sudo will install into your system Python. Instead, use “workon” to access your Python virtual environment and then “pip install imutils”. If you’re not using a Python virtual environment let me know.
Hi Adrian,
I am getting the same error as Peen, that is I get ImportError: No module named imutils.video even though I have successfully installed imutils. I am NOT using a Python virtual environment (because I cannot create it for some reason, even though I followed your tutorial for installing OpenCV).
Thank you!
Hi Adrian,
I’ve combined this tutorial with your other tutorial to control an LED when an green surface is detected. I need to scan barcodes and check them with a preferred barcode, when the barcode differs from the preferred one it will give a signal to an LED. To ensure a good scan I made a flashlight which will lighten the barcode. Unfortunately the camera change automatically the parameters of the brightness and contrast. How can I set the contrast to an preferred number? I use this for the stream:
vs = VideoStream(src=0).start()
frame = vs.read()
frame = imutils.resize(frame, width=400)
I’ve tried to put some set parameters but every time I get aan AttributeError.
I placed “vs.__init.set(CV_CAP_PROP_BRIGHTNESS, 0.1) after the vs = VideoStream(src=0).start()
Can you help me with this, please?
Kind regard,
Raymond
The VideoStream class is not intended to have the camera properties set that way. I have an idea to update the “src” attribute with a pre-initialized cv2.VideoCapture object in the future but haven’t been able to.
Instead, I would suggest you use the WebcamVideoStream form imutils instead. Before you run the .start() method of the object you can set any camera properties:
vs.stream.set(cv2.PROPERY_NAME_HERE, value)I was thought about to make a mini project on the technology-based something and after visit this blog I have got the idea to try this in my project using zbar for scanning barcode and QR code. keep posting this kind of interesting technology-based experiments.
Hi Adrian,
I have followed your instructions, and it works great. However, when I have a small QR code; approximately 0.7 inch x 0.7 inch, the QR code can’t be detected. Is there anyway to improve it? Thank you
You may want to consider resizing your image and increasing the resolution of your input image prior to passing it through the detector.
Dear Adrian, firstval i congratulate you for the great qork you’ve done. I have a question, i’m just a beginner, can i get the streaming from an IP Camera with VideoStream Class? Thanks.
Provided you use
vs = VideoStream(src="your IP path")it should work.Thanks! It worked. The Ip camera detects only QRcode but when i try to detect barcode, it dosn’t work. Dou you have any idea? Thanks
I had some issues with ZBar detecting some barcodes. It always worked really well for QRcodes but not always barcodes. I think it may be a limitation of the ZBar library itself.
My PiCamera was initially unable to detect barcodes because the image itself was too blurry, so it wasn’t able to detect the barcode. Manually adjusting the focus (rotating it counter clockwise) of the camera fixed this for me. Keep in mind, the camera is now essentially set up to only focus on close-up images, and is blurry further away.
I found the idea here: https://www.jeffgeerling.com/blog/2017/fixing-blurry-focus-on-some-raspberry-pi-camera-v2-models
I was able to rotate the focus using my fingernails while supporting the base of the camera. Hope this helps get a more crisp image!
what if i have an entry of almost 50k barcode values in the csv file and i have to cross check one value that i read using a code that goes through the main csv file. How much time in average will it take if the particular barcode value is almost at the last of csv file.
I would suggest you run an experiment and see as it will depend on which hardware you are using. Generate 50K barcode entries and then run your matching algorithm.
hello,
the frame rate for real time barcode snanning is low. any method that can increase the frame rate for video using a webcam.
Hey John, did you try the code on your system? The frame rate is actually much higher than it appears on the GIF animations. To create the GIFs I just wrote a Python script to take a screenshot every two seconds.
Hey Adrian, great tutorial, I got this up and running in no time. I was hoping to use this through ssh, and I was able to do that by commenting out the cv2.imshow line, and that allows it to work well enough for me. However, it would be a great bonus if I could stream the actual video via ssh in addition to the data. Is that doable or would that be a whole additional project?
Thanks for any advice. By the way I’m running this on a Raspberry Pi 3
You can use “cv2.imshow” and have the result streamed to your machine connected to the Pi by enabling X11 forwarding:
$ ssh -X pi@your_ip_addresshey adrian first of all thanks for this wonderful tutorial,i got the output but i need to print the barcodes in a seperate terminal how can i do that?
What do you mean by a “separate terminal”?
What if I use this on a raspberry pi controlled drone? Will it be able to detect the QR code while the drone is moving at a certain speed? There is probably a threshold speed for this right? Is that speed high enough?
Hi adrian
I am following your tutorial for qr code scanner but when i m trying to import pyzbar its keep saying “no module named pyzbar”
But i have installed it on my virtual environment… Can you please explain what is the problem here???
Hey Fariya — my guess is that you may be forgetting to install pyzbar into your Python virtual environment and/or you installed pyzbar outside the Python virtual environment but are trying to execute the code within a virtual environment.
Thanks a lot.
Any idea how to try to detect a 3cm*3cm from 3 to 5 m away?
it seems that far distance will be a large problem
Thanks a lot
hi Adrian, thanks for this great topic, I have a question, in my case i have a server that generate qrcode, i want to post them to a raspberrypi connected to turnstile door, so when a person scan the qrcode the raspberrypi will check the database in the server and if the qr exist it will trigger the door.
do you have an idea what is the best way to implement it and in real time?
thanks
Hey Syed, this sounds less like a computer vision problem and more like an actual “engineering” problem. If you’re new to basic web servers and databases I would suggest you read up on them first. I’m happy to help and provide suggestions but again, I ask that the questions be related to computer vision.
Hi Adrian want to use this code for small QR code (0.75×0.75 in) but It doesnt work with this size, how can I change the frame rate or resolution using imutils? Pleas help is for a Univerity project
Take a look at Line 32 — that line will control the spatial dimensions the input frame is resized to.
I tried the video stream option with both pi camera and a USB web cam, neither one recognizes the QR code in it. I adjusted the USB web cam focus to make sure the video quality is clear to show the QR code, however it still doesn’t recognize it. When I tried to take still picture of the QR code printed in a piece of paper held in front of the USB Web Cam, it turned out ok. So is this because pyzbar can’t recognize the qr code in the video feed or something else about the web cam? I didn’t see any error message printed out.
This is absolutely brilliant. Is there a simple way to break down a large text file into several qr codes and then put it back together?
Thanks Daniele, I’m glad you liked the post. As for “breaking down larger text” I’m not sure what you are referring to. Could you elaborate?
Nice Tutorial, What should I do if I want to save the detected code(QR) in a text file or redirect the URL in a browser. Could you please explain?
The code covered in “barcode_scanner_video.py” already shows you how to save the decoded QR code to a text file. Please refer to it.
Thank you sir..
hi
Is Raspberry pi zero could use with the an openCV barcode and QR code scanner with Zbar??
thank you Adrian Rosebrock
I haven’t tried but I assume it would work.
Nice tutorial, I could use it to make a quadcopter.
A quadcopter that does barcode recognition…?
yes…
I’m not sure how that would work exactly. Quadcopters move very quickly and often introduce motion blurring into frames. Barcode scanners on the other hand normally require high quality images of the barcodes. Realistically I think you would struggle to make such a solution work.
Exactly, but I’m optimizing this issue
thanks adrian for ur awesome tutorial , i have already successfully install open cv in my raspbians…Back to my question, I apologize for asking a newbie question, but may i know WHERE DO U insert all these codes from line 1 onwards , is it through the terminal or other platform ?
i mean as in how do u open the “new file”
You could use your favorite text editor or a full-fledged programming IDE. I really like Sublime Text 2 and PyCharm.
hi adrian, i have a problem with the code in real time.
I’m using a PiCamera and I’m getting error:
from picamera.array import PiRGBArray
ImportError: No module named ‘picamera’
so why did the importError happened?
It sounds like you do not have the “picamera” library properly installed on your machine:
$ pip install "picamera[array]"Yes, that was the problem,
thanks
Hi Adrian,
Thanks for the post. I have been struggling to get OpenCV to install, so I followed the PIP install, and got that completed, inside the Virtualised env.
I then installed the ZBar tools in the same environment.
When i try to process a still image, i get the message:
: cannot connect to x server
This seems to be happening with the code
(x, y, w, h) = barcode.rect
Any ideas? I am just using an image with two barcodes on it.. taken with the pi cam.
Thanks,
James
Hi Adrian..
The issue was I am trying this via ssh… rather than via the GUI on the Pi.
Any tips to getting this working via SSH?
Thanks,
James
Make sure you are enabling X11 forwarding if you are SSH’ing into your Pi:
$ ssh -X pi@your_ip_addressgreetings adrian, do u have any idea that i can place the information that i gather from the qr code to compile them in any sheets , eg: google spreadsheet, appreciate ur assistance
I would research the Google Docs APIs. I’m not familiar with them but I’m sure it’s possible to programmatically access a Google Sheet and add the data. That’s really outside the context of the blog post though. Best of luck with the project!
Hello Adrian, Can i get decode qrcode and stop video stream to next step like access door lock or query to database ? i tried your code but i couldn’t query to database because result decode is stream and not stop when take/decode qrcode.
Sorry Ricky, I’m not sure what you mean here. Is your goal to detect a QR code and then have it perform an automation like open a door?
On the Raspberry Pi Zero W, I was receiving an “Illegal instruction” error while trying to run the code samples.
I found a [github issue](https://github.com/jrosebr1/imutils/issues/76#issuecomment-412330063) that explained what was happening.
The solution was to change this line
> frame = imutils.resize(frame, width=400)
to this
> frame = imutils.resize(frame, width=400, inter=cv2.INTER_CUBIC)
Indeed, it’s a strange issue. I truthfully have no idea why it’s happening.
how can I break the while loop after i have scanned the code or codes I want?
Press the “q” key on your keyboard with the window opened by OpenCV active.
i have a problem. it can not read some Qr Code includes Turkish characters. How can solve the problme
I would reach out to the zbar developers directly and ask them what else you could do to improve accuracy for Turkish characters.
Posting was really helpful! 😀 By the way, I want to control the relay using the QR code.
Can you tell me how I would like to operate the relay if it recognizes the QR code?
What “relay” are you referring to? I suggest you consult the documentation of your relay.
Excelent Adrian but when running my code a “ValueError: too many values to unpack (expected 2) ” appears so i don´t know if it is because it is a utf-8 decoding and zbar asks for a uint8 type. Thank you!!!!!!!!!!!!!!
What line of code is throwing that error, David?
Hi Adrian
I need to make a qr code scanner for a schoolproject so I followed your guide. I copied your code to a text file (with nano) and then changed to rights to make it an executable file. Then I went out of the virtual workspaceto test it using “$ python barcode_scanner_image.py –image barcode_example.png” but it says “command not found”. do you have any idea what I did wrong? (I’ve also tried to execute it in the ‘barcode’ workspace but same problem. And the image to test is in my download folder. Thanks a lot!
Don’t copy and paste the code — make sure you use the “Downloads” section of the tutorial to download the source code and example images. You may have introduced an error while copying and pasting.
Hi Adrian,
Thank you for all your incredible tutorials, they are well explained.
the library Zbar work only for barecode and QRcode.there is a library for datamatrix decode.Can you help me to decode a datamatrix from a picture.
I want to import serial Real-time barcode and QR code reading with OpenCV this code.
but I get an error. please Could you tell me how?
What is the error you are receiving? Without knowing the error I cannot provide any suggestions.
The error message looks like this:
import serial
ImportError: No module named ‘serial
I want to make serial communication with Arduino. Thank you.
It sounds like you haven’t installed the PySerial Python package. Perhaps try:
$ pip install pyserialHi Adrian,
Thank you so much for this example, personally I had to download another lib packages to my raspberry to use imutils and cv2.
I was getting two errors when importing this files:
-ImportError: libf77blas.so.3: cannot open shared object file: No such file or directory
This was solved by typing this command:
sudo apt-get install libatlas-base-dev
-ImportError: libjasper.so.1 cannot open shared object file: No such file or directory
This was solved by typing this command:
sudo apt-get install libjasper-dev
After this I could manage to get everything running. Just some questions, the reading seems a little bit slow and it shows the rectangle from the raspi cam very small. Do you know how can we improve this to visualize everything better?
And also, I cannot seem to read any barcode, just some QRs. Does the barcode_scanner_video.py works for both?
Hello I managed to read barcodes by adjusting the camera lens focus manually because the image was very blurry. Now it works great! I can read almost any barcode and tons of QRs.
For the reading speed, I didn’t actually needed to store the data on a csv file, so I comment that code lines and the everything improved a lot.
I changed the code a bit to have live video since the beginning and to toggle a green led whenever it detects a qr and a barcode I stored before and a red led whenever the barcode/qr is different. I will post my code here once I finish everything.
Thank you!
Congrats on resolving the issue Gaby! And nice job implementing your script 🙂
Please share your code with us. I want to develop same project, it would be so helpy.
Thanks alot, I look forward to your response.
Hi so I have been having a problem with Zbar and I was hoping you could help. I have it so I can scan and decode the qrcode but the problem is that it just shows it under my command(I am just using the raspberry pi terminal) and doesn’t do anything with it. Say if I have a url encoded into my qrcode and I use the zbar to decode it it just shows a url code verse actually putting the url in a browser or even a text file. Do you know of a way to export the output of pyzbar?
The code in this tutorial is meant to show you how to extract the value of the QR code or barcode. Exactly what you do after you recognize the code is up to you. It sounds like you want to take the URL and automatically open it in a browser. That sounds very OS and GUI specific so I would suggest you research OS and GUI libraries that can control your browser.
This is fantastic! Looking forward to trying the 2nd part with a webcam.
Thanks!
Hi,
Very nice tutorial and Thanks.
I have one issue , it reads all qr codes except white barcodes . Is there any option for that?
Thanks in advance.
Have you tried inverting the barcode? I would suggest reaching out to the Zbar library developers if it’s specifically related to a type of barcode.
Hi Adrian,
Great project you present here !
i was wondering, is there a way to shut down the streaming once the barcode is detected ?
thanks in advance
Once you’ve detected a barcode and read it you can
breakfrom thewhileloop and shut down the streaming.Hi Adrian,
Your work is great, thank you very much.
But I have a problem, that is, the recognition of Chinese garbled.
For example, “中文” cannot be decoded correctly.
I have been trying for a long time and can’t realize Chinese recognition.
Do you have a solution?
I haven’t tried using ZBar with Chinese characters. There is a thread regarding the question on the ZBar forums, I would suggest starting there.
Hi Adrian,
Thanks for your wonderful post.
I have a problem, I hope you can give me some suggestion to fix it.
When I run the script the writing “[INFO] starting video stream…” appears. After that only when I put a QRcode in front of the PiCamera the “barcode scanner” window opens, but it is black, no image on it.
Do you have any idea to fix that?
Kind Regards
Dario
It sounds like a problem with the Raspberry Pi camera module. See this tutorial for a solution.
Reading a barcode from long distance is not possible. Does it depend hardware or code? How can detect and read barcode from long distance?
Sincerely,
Fairy.
Hi Adrian,
Thanks for the nice post.
I’m not able to install zbar library.I’m using ubuntu 18.04.Please help.
Regards,
Hussain
What errors are you running into?
thanks a lot sir,for the work you shared with us
but, i am not able to run this code using laptop’s camera.can you help me in solving this issue
Can you be more specific? Are you getting an error of some sort?
Adrian , thank a lot , it work 100% for me by reading video form my laptop and pass it to your code
That’s great, I’m glad it worked for you!
Hey Adrian, thank you so much for the code. Your works is clean and professional. However, I am really new to this so can I use a MAC VMware on my windows laptop and use my laptops camera. Would that work? Thank you
Yes, but you’ll want to refer to the VMware documentation on how to allow access to your host webcam — VMware will block that by default.
Hi, is there any additional argument or parameters which can be passed to the decode function that will allow for identical barcodes found in an image to be N number of Decoded data?
As of now, only 1 Decoded result was shown when I was trying to decode the attached image. Thanks
I don’t think there is but you should consider reaching out to the zbar library developers for a more conclusive answer.
Hi Adrian, I am a design student in the UK and I’m using a Pi and a few different camera modules to optimise your real-time barcode scanner as much as possible. I only need zbar to read QR codes at further distances and I was wondering if you can create the illusion of a higher frame rate using a different camera module or USB camera or even your ‘pi object detection’ blog post? Would I be better running the programme from a laptop? I’m a total beginner to this but I am learning fast with thanks to your blogs, Thanks in advance
Hi,Adrian .First of all thank you so much for the code .Actually ,i was running it on Raspberry pi and as i am not having pi camera i was trying to access it using webcam of the laptop but it shows me error :
“VIDEOIO ERROR: V4L: can’t open camera by index 0 ”
Please can you help in resolving this issue and Thanks alot.
Are you using a Raspberry Pi camera module? If so, Make sure Line 18 is commented out and Line 19 is uncommented.
Thank you for the code. Works perfectly. I ran in on my Macbook. Minor modification and I got it the way I like it.
Thanks Budi! And congrats on a successful project.
Which are the other Python barcode decoding library apart from zbar ?
Is it possible to recognize and decode multiple barcodes simultaneously? I an looking to quickly video 80-100 barcodes on boxes and pass them to an external api.
Hi,
Thanks for great tutorial! works great, i ended up using a hd920 did not find the rpicam good enough when the distance got a bit longer.
I am trying to build a delay or stop in the script that will wait on motion detect. can’t really get it right. Could you point me in the right direction? (i am not barcodedata to found since i want all barcodes to be logged, however i want the program to stop and wait untill a change has occured in the frame. )
Thanks in advance!
//J
What do you mean by a delay/stop? What is the goal of using it?
Hi,
Thanks for the nice explanation.
Will it work for pdf417 barcode?
I’m not sure, you would need to refer to the ZBar documentation.
Hi Adrian,
What can you say about performance on RPI?
Which is de minimum or average time to detect and process a QR code?
And in wich conditions: RPI version, image resolution, ….
Hi Adrian,
Many thanks for the clear instructions. I had no previous experience, however managed to get it work with your step by step instructions.
Going to use it practically to register the attendance (low cost system)
Thanks again.
Thanks Samith — and congrats on getting up and running with OpenCV and ZBar!
Hi Adrian,
I am doing a project using your tutorial, where the moving robot should detect QR codes on the ground and stop, but on motion, my robot is not detecting the qr code. Could you please provide me with a better approach in achieving this task. I am using a webcam and my laptop as a computer.
Thanks
Krishna
Sorry, I cannot write custom code for your project. I would suggest debugging the QR code detection first before you even attempt controlling the robot. Make sure your code + camera can correctly recognize the QR code.
Hi Adrian,
I am doing a project in which i have to detect QR Codes from bill images. But PyZBar is not detecting the QR Codes because they are not clear and are at some angle not flat images. What should i do?
Hi Adrian,
thanks for that tutorial it just works fine. But i’ve got a problem. I try to take a picture after detecting the qr-codes. I tried with subprocess and raspistill, but i get the mmal: Problem.
Could you please tell me how to take a picture while the videostream is opened?
Thanks a lot
Patrick
You can’t. The Python script has access to the camera — two processes cannot access the camera at once. Instead, just use “cv2.imwrite” to save the frame to disk via the Python script.
Hi Adrian
I love the simplicity of your tutorials, I’ve been able to get a static barcode reader code to work but I’ve been very hamstrung by having real trouble getting the PIP installs to work at all on my windows 10 desktop (running 64 bit Python 3.7). I managed to get somewhere by taking CV2 instead of opencv-python and I found a site that allowed me to download numpy and PIP install in a CLI (https://www.lfd.uci.edu/~gohlke/pythonlibs/). I haven’t been able to download imutils at all so am stuck at this point.
Also, I’ve installed the packages locally from the download but I want the software within a virtual environment within PYcharm and I’m not sure how that can be done.
Any help would be gratefully received, the barcode read element is crucial to what I’m trying to do.
Hi Adrian,
I attached my OpenMV USB cam to my raspberry pi. I commented out line 19 and uncommented line 18, however I get an error saying ‘NoneType’ object has no attribute ‘shape’. Ive tried going through your article here https://www.pyimagesearch.com/2016/12/26/opencv-resolving-nonetype-errors/ …but I couldn’t find a solution that works in my case..Am I missing something? any help would be appreciated!
-Zaya
hi adrian,
thx for your great work
Thanks Owen!
Thanks for the tutorial! The pyzbar seems to not recognize UAC-A, UPC-E and other types of barcodes. Can’t really find good documentation on this. I don’t want a leading zero added to my UPC-A barcodes.
Any suggestions? Another zbar library possibly?
Amazing tutorial, I got it working but i would like it to close automatically after 15 seconds and not with the q key, I added a time.sleep(15) right after key = cv2.waitKey(1) & 0xFF and it works but the barcode scanner windows is kinda laggy; where should i put that sleep?
Thanks in advance. 🙂
Hi,
I want to read barcodes in real time and then play videos corresponding to a certain barcode on the pi. Any suggestions?
Hi,
Great tutorial,
how would i rotate the camera 180 degrees for the output?
hi, i have managed to flip this output but my QR code translation is now upside doen how do i fix this
thanks
What types of QR codes does zbar support? Is there a reference?
Yes, the ZBar documentation covers it.
Hi Adrian!
Can you please explain or direct me to information about the algorithm being used in QR Code Recognition in Zbar
I would suggest reading the ZBar documentation for more details.
Adrian, since your article was originally written, OpenCV has added a QR Code detector. Have you had any opportunity to explore?
Is ZBar still the better library for QR Code detection?
https://docs.opencv.org/3.4/de/dc3/classcv_1_1QRCodeDetector.html