Barcode Recognition Routine Explanation#

Overview#

A barcode is a visual pattern used to represent data, encoding information through stripes or patterns of different widths and spacings. Barcodes are widely used across various industries for automatic identification, storage, and management of data.

CanMV supports OpenMV algorithms and can recognize barcodes. The relevant interface is find_barcodes, which supports multiple barcode formats.

Example#

This example sets the camera output to a 640x480 grayscale image and uses image.find_barcodes to recognize barcodes.

Tip

If the recognition success rate is low, try adjusting the camera’s mirror and flip settings, and make sure to leave a white area on both sides of the barcode.

# Barcode detection example
import time
import math
import os
import gc
import sys

from media.sensor import *
from media.display import *
from media.media import *

# Function: Get the name of the barcode type
def barcode_name(code):
    barcode_types = {
        image.EAN2: "EAN2",
        image.EAN5: "EAN5",
        image.EAN8: "EAN8",
        image.UPCE: "UPCE",
        image.ISBN10: "ISBN10",
        image.UPCA: "UPCA",
        image.EAN13: "EAN13",
        image.ISBN13: "ISBN13",
        image.I25: "I25",
        image.DATABAR: "DATABAR",
        image.DATABAR_EXP: "DATABAR_EXP",
        image.CODABAR: "CODABAR",
        image.CODE39: "CODE39",
        image.PDF417: "PDF417",
        image.CODE93: "CODE93",
        image.CODE128: "CODE128",
    }
    return barcode_types.get(code.type(), "Unknown Barcode")

# Define image detection width and height
DETECT_WIDTH = 640
DETECT_HEIGHT = 480

sensor = None

try:
    # Construct Sensor object using default configuration
    sensor = Sensor(width=DETECT_WIDTH, height=DETECT_HEIGHT)
    # Reset sensor
    sensor.reset()
    # Set output size and format
    sensor.set_framesize(width=DETECT_WIDTH, height=DETECT_HEIGHT)
    sensor.set_pixformat(Sensor.GRAYSCALE)

    # Initialize display
    Display.init(Display.VIRT, width=DETECT_WIDTH, height=DETECT_HEIGHT, fps=100)

    # Initialize media manager
    MediaManager.init()
    # Start sensor
    sensor.run()

    fps = time.clock()

    while True:
        fps.tick()

        # Check if should exit
        os.exitpoint()
        img = sensor.snapshot()

        # Recognize barcodes in the image
        for code in img.find_barcodes():
            img.draw_rectangle([v for v in code.rect()], color=(255, 0, 0))  # Draw a rectangle around the recognized barcode
            print_args = (
                barcode_name(code),
                code.payload(),
                (180 * code.rotation()) / math.pi,
                code.quality(),
                fps.fps()
            )
            print("Barcode %s, Content \"%s\", Rotation %f (degrees), Quality %d, FPS %f" % print_args)

        # Draw the result onto the screen
        Display.show_image(img)
        gc.collect()

except KeyboardInterrupt:
    print("User stopped")
except BaseException as e:
    print(f"Exception '{e}'")
finally:
    # Stop sensor
    if isinstance(sensor, Sensor):
        sensor.stop()
    # Destroy display
    Display.deinit()

    os.exitpoint(os.EXITPOINT_ENABLE_SLEEP)
    time.sleep_ms(100)

    # Release media buffers
    MediaManager.deinit()

Code Description#

Import modules: Import the necessary libraries to use sensor, display, and media management functions.
barcode_name function: Returns the name of the barcode based on its type, facilitating subsequent processing and display.
Sensor configuration: Create and configure the sensor object, including setting the output image width, height, and format (grayscale image).
Display initialization: Configure the display output method, with options for HDMI, LCD, or IDE.
Main loop:
- Capture images and check exit conditions.
- Recognize barcodes in the image and draw a red rectangle around them.
- Print detailed barcode information, including type, content, rotation angle, quality, and current frame rate.
Exception handling: Catch user interruption or other exceptions to ensure the sensor stops properly and resources are released.

Tip

For specific interface definitions, please refer to find_barcodes.

Barcode Recognition Routine Explanation

Contents

Barcode Recognition Routine Explanation#

Overview#

Example#

Code Description#