Welcome to AI View Depth camera repository

2. QR code creation and recognition

2.1. QR QR code

2.1.1. QR QR code introduction

QR code is a type of two-dimensional barcode. QR comes from the abbreviation of "Quick Response" in English, which means quick response. It comes from the inventor's hope that QR code can allow its content to be decoded quickly. QR code not only has large information capacity, high reliability and low cost, but also can represent a variety of text information such as Chinese characters and images. It has strong confidentiality and anti-counterfeiting properties and is very convenient to use. More importantly, the QR code technology is open source.

2.1.2. QR QR code structure

2.1.3. QR QR code characteristics

The data value in the QR code contains repeated information (redundant value). Therefore, even if up to 30% of the QR code structure is destroyed, it does not affect the readability of the QR code. The storage space of the QR code is up to 7089 bits or 4296 characters, including punctuation and special characters, which can be written into the QR code. In addition to numbers and characters, words and phrases (such as URLs) can also be encoded. As more data is added to the QR code, the code size increases and the code structure becomes more complex.

2.1.4, QR code creation and recognition

1), create QR code

• Source code path

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~/orbbec_ws/src/yahboomcar_visual/simple_qrcode/QRcode_Create.py

• Installation package

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python3 -m pip install qrcode pyzbar
sudo apt-get install libzbar-dev

• Start

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cd ~/orbbec_ws/src/yahboomcar_visual/simple_qrcode
python QRcode_Create.py

After the program runs, it will prompt you to enter the generated content, and press Enter to confirm the content. Here we take the creation of the "yahboom" string as an example,

• Core source code analysis

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#Create qrcode object
qr = qrcode.QRCode(
version=1,
error_correction=qrcode.constants.ERROR_CORRECT_H,
box_size=5,
border=4,)
#Meaning of each parameter
'''version: An integer with a value of 1 to 40, controlling the size of the QR code (the minimum value is 1, which is a 12×12 matrix).
If you want the program to determine it automatically, set the value to None and use the fit parameter.
error_correction: Controls the error correction function of the QR code. The following 4 constants can be used.
ERROR_CORRECT_L: About 7% or less of the errors can be corrected.
ERROR_CORRECT_M (default): About 15% or less errors can be corrected.
ERROR_CORRECT_H: About 30% or less errors can be corrected.
box_size: Controls the number of pixels contained in each small grid in the QR code.
border: controls the number of grids contained in the border (the distance between the QR code and the image border) (the default is 4, which is the minimum value specified by the relevant standards)'''
#qrcode QR code adds logo
my_file = Path(logo_path)
if my_file.is_file(): img = add_logo(img, logo_path)
#Add data
qr.add_data(data)
#Fill data
#fill data
qr.make(fit=True)
#Generate images
#generate images
img = qr.make_image(fill_color="green", back_color="white")

2), identify QR code

• Source code path

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~/orbbec_ws/src/yahboomcar_visual/yahboomcar_visual/QRcode_Parsing.py

• Start

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#gemini camera start
ros2 launch astra_camera gemini.launch.xml
ros2 run yahboomcar_visual QRcode_Parsing

• View node communication diagram

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ros2 run rqt_graph rqt_graph

• Core source code analysis

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#Subscribe to color image information
self.sub_img = self.create_subscription(CamImage,'/camera/color/image_raw',self.handleTopic,100)
#Pass the image data to the image parsing function in the callback function
frame = self.decodeDisplay(frame)
# parse the image
def decodeDisplay(self,image):
gray = cv.cvtColor(image, cv.COLOR_BGR2GRAY)
# The output Chinese characters need to be converted to Unicode encoding first
barcodes = pyzbar.decode(gray)
for barcode in barcodes:
# Extract the position of the boundary box of the TWO-DIMENSIONAL code
# Draw the bounding box for the bar code in the image
(x, y, w, h) = barcode.rect
cv.rectangle(image, (x, y), (x + w, y + h), (225, 0, 0), 5)
encoding = 'UTF-8'
# to draw it, you need to convert it to a string first
to convert it to a string
barcodeData = barcode.data.decode(encoding)
barcodeType = barcode.type
# Draw the data and type on the image
pilimg = Image.fromarray(image)
# create brush
draw = ImageDraw.Draw(pilimg) # Print on picture
# parameter 1: font file path, parameter 2: font size
fontStyle = ImageFont.truetype("/home/yahboom/orbbec_ws/src/yahboomcar_visual/yahboomcar_visual/Block_Simplified.TTF", size=12, encoding=encoding)
# # Parameter 1: print coordinates, parameter 2: text, parameter 3: font color, parameter 4: font
# Parameter 1: print coordinates, parameter 2: text, parameter 3: font color, parameter 4: font
draw.text((x, y - 25), str(barcode.data, encoding), fill=(255, 0, 0), font=fontStyle)
# # PIL picture to cv2 picture
# PIL picture to CV2 picture
image = np.array(pilimg)
# Print barcode data and barcode type to terminal
# Print barcode data and barcode type to terminal
print("[INFO] Found {} barcode: {}".format(barcodeType, barcodeData))
return image