A barcode is a method of representing data in a visual and machine readable form, it consists of bars and spaces. Today, we see barcodes everywhere, especially in products in supermarkets.
Barcodes can be read by an optical barcode scanner, but in this tutorial, we will make a script in Python that is able to read and decode barcodes, as well as drawing where they're located in a given image.
To get started, we need to install few libraries:
pip3 install pyzbar opencv-python
Once you have these installed, open up a new Python file and import them:
from pyzbar import pyzbar import cv2
I have few images to test with, you can use any image you want from the internet or your own disk, but you can get my test images in this directory.
I have wrapped every functionality into a function, the first function we gonna discuss is the following:
def decode(image): # decodes all barcodes from an image decoded_objects = pyzbar.decode(image) for obj in decoded_objects: # draw the barcode print("detected barcode:", obj) image = draw_barcode(obj, image) # print barcode type & data print("Type:", obj.type) print("Data:", obj.data) print() return image
decode() function takes an image as a numpy array, and uses
pyzbar.decode() that is responsible for decoding all barcodes from a single image and returns a bunch of useful information about each barcode detected.
We then iterate over all detected barcodes and draw a rectangle around the barcode and prints the type and the data of the barcode.
To make things clear, the following is how each
obj looked like if we print it:
Decoded(data=b'43770929851162', type='I25', rect=Rect(left=62, top=0, width=694, height=180), polygon=[Point(x=62, y=1), Point(x=62, y=179), Point(x=756, y=180), Point(x=756, y=0)])
pyzbar.decode() function returns the data containing the barcode, the type of barcode, as well as the location points as a rectangle and a polygon.
This brings us to the next function that we used,
def draw_barcode(decoded, image): # n_points = len(decoded.polygon) # for i in range(n_points): # image = cv2.line(image, decoded.polygon[i], decoded.polygon[(i+1) % n_points], color=(0, 255, 0), thickness=5) # uncomment above and comment below if you want to draw a polygon and not a rectangle image = cv2.rectangle(image, (decoded.rect.left, decoded.rect.top), (decoded.rect.left + decoded.rect.width, decoded.rect.top + decoded.rect.height), color=(0, 255, 0), thickness=5) return image
This function takes the decoded object we just saw, and the image itself, it draws a rectangle around the barcode using
cv2.rectangle() function, or you can uncomment the other version of the function; drawing the polygon using
cv2.line() function, the choice is yours. I preferred the rectangle version.
Finally, it returns the image that contains the drawn barcodes. Now let's use these functions for our example images:
if __name__ == "__main__": from glob import glob barcodes = glob("barcode*.png") for barcode_file in barcodes: # load the image to opencv img = cv2.imread(barcode_file) # decode detected barcodes & get the image # that is drawn img = decode(img) # show the image cv2.imshow("img", img) cv2.waitKey(0)
In my current directory, I have barcode1.png, barcode2.png, and barcode3.png, which are all example images of a scanned barcode, I used glob so I can get all these images as a list and iterate over them.
On each file, we load it using
cv2.imread() function, and use the previously discussed
decode() function to decode the barcodes and then we show the actual image.
Note that this will also detect QR codes, and that's fine, but for more accurate results, I suggest you check the dedicated tutorial for detecting and generating qr codes in Python.
When I run the script, it shows each image and prints the type and data of it, press any key and you'll get the next image, here is my output:
detected barcode: Decoded(data=b'0036000291452', type='EAN13', rect=Rect(left=124, top=58, width=965, height=812), polygon=[Point(x=124, y=59), Point(x=124, y=869), Point(x=621, y=870), Point(x=1089, y=870), Point(x=1089, y=58)]) Type: EAN13 Data: b'0036000291452' detected barcode: Decoded(data=b'Wikipedia', type='CODE128', rect=Rect(left=593, top=4, width=0, height=294), polygon=[Point(x=593, y=4), Point(x=593, y=298)]) Type: CODE128 Data: b'Wikipedia' detected barcode: Decoded(data=b'43770929851162', type='I25', rect=Rect(left=62, top=0, width=694, height=180), polygon=[Point(x=62, y=1), Point(x=62, y=179), Point(x=756, y=180), Point(x=756, y=0)]) Type: I25 Data: b'43770929851162'
Here is the last image that is shown:
That is awesome, now you have a great tool to make your own barcode scanner in Python. I know you all want to read directly from the camera, as a result, I have prepared the code that reads from the camera and detects barcodes in a live manner, check it here!
You can also add some sort of a beep when each barcode is detected, just like in supermarkets, check the tutorial for playing sounds which may help you accomplish that.
For more detailed information, I invite you to check pyzbar documentation.
Learn also: How to Generate and Read QR Code in Python.
Happy Coding ♥View Full Code