Gain insights into using Python to read and write optical labels, explore 1D and 2D barcodes, and fiduciary markers for augmented reality, and discover relevant Python libraries and applications.

Reading _ Writing Machine-Readable Optical Labels with Python .jpg

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Course

Gradio

Gradio-2

Gradio-3

Machine-readable optical labels are visual representations of data that machines can read and interpret. These labels, often composed of simple geometric shapes or lines, are designed to encode various kinds of information, such as product details or reference numbers.

In this course, you’ll be introduced to Python-based reading and writing of 1D and 2D barcodes and fiduciary markers. You’ll then learn the practical applications of barcodes and fiduciary markers in augmented reality and the creation of user interfaces for reading barcodes. Next, you’ll learn about different Python libraries and their usage to process different optical labels.

By the end of the course, you’ll be proficient in using Python for handling barcodes and fiduciary markers. You’ll also have hands-on experience installing and using different Python libraries to manipulate optical labels.

Using Python for Reading and Writing Optical Labels

Here is a quick example that shows how to generate a QR code containing a link to the Educative website:


import qrcode  
data = 'https://educative.io' 
img = qrcode.make(data)
print(type(img))
img.save('output/qrcode.png')

**Line 1:** First, we import the `qrcode` library.

**Line 2:** Then, we define the `data` we wish to encode in the QR code. In this case, we use the URL of the Educative website. This data can be any kind of character string data. It doesn't have to be a URL.

**Line 3:** By using the `qrcode.make()` function, we generate a QR code using the `data` we just defined. The output is a `PIL` image. Consequently, we can apply all the image operations from the `PIL` library to the resulting image.

**Line 4:** We show that the type of output from the above function is indeed an image. For this, we use a `print(type())` statement. 

**Line 5:** Finally, we use the `save()` method on the `PIL` image to save the QR code image to a PNG file.

The `qrcode` library also allows us to create QR codes using various parameters. With this, we can achieve more control over the generated QR codes.

Below, we can see a more advanced example using various parameters:




import qrcode 
qr = qrcode.QRCode(  
    version = 2,  
    error_correction = qrcode.constants.ERROR_CORRECT_H,  
    box_size = 10,  
    border = 2,  
)  

data = 'https://educative.io' 
qr.add_data(data)
qr.make(fit = True)  

img = qr.make_image(fill_color = "black", back_color = "white") 
img.save('output/qrcode.png')

**Lines 2–7:** To start out, we define an instance of the `qrcode.QRCode()` class. This constructor allows us to set a few parameters.

**Line 3:** Here, we first set the `version` of the QR code to `2`. As we mentioned before, QR codes can have version numbers from 1 to 40. 

These version numbers determine the size of the generated code. QR codes of version 1 are the smallest, whereas those of version 40 will be the largest.

**Line 4:** The next parameter we set in the example is `error_correction`. This sets the error correction level. 

Again, as mentioned before, there are four levels of error correction. To set these levels, we need to use the predefined constants from the `qrcode` library:

 * `qrcode.constants.ERROR_CORRECT_L`: For correcting 7% or less errors.
 * `qrcode.constants.ERROR_CORRECT_M`: For  correcting 15% or less errors. 
 * `qrcode.constants.ERROR_CORRECT_Q`: For correcting 25% or less errors.
  * `qrcode.constants.ERROR_CORRECT_H`: For correcting 30% or less errors.

The default error correction level is `M`, but for the example, we set it to `H`.

**Line 5:** Then, we set the `boxsize` parameter. This parameter determines the size of each pixel in the generated QR codes. In this example, we set it to `10`.

**Line 6:** Finally, we set the `border` parameter. This determines the size of the border around the QR code. According to the official specifications of QR codes, the minimum value should be `4`, but here, we set it to `2` as an example. If this parameter is not set, it will default to `4`.

**Lines 9–10:** Once we have created an instance of the `QRCode` class called `qr`, we can define and add the data to this object. The data is the same as we used previously---the URL of the Educative website. We add this data by using the `add_data()` method.

**Line 11:** By calling the `make()` method on the `qr` object, we tell it to generate the QR code array. Here, we set the `fit` parameter to `True` such that the minimum size code will be generated that can contain the data. 

If, as in this example, the version is set to a given value, this will be considered the lower bound. So, if a higher version is needed to contain all the data, then this will be determined because the `fit` parameter is set to `True`.

**Line 13:** Finally, we’ll use the `make_image()` method to generate an image. Here, we can also set the colors of the pixels and the background. The pixel color is set to black using `fill_color`, and the background color is set to `white` with `back_color`. 

Both parameters accept a character string with the color name or RGB color tuples.


Learn how to generate and read different kinds of QR codes.

Introduction to Machine-Readable Optical Labels

An Overview of Barcodes

Reading and Writing 1D Barcodes With Python

Reading and Writing 2D Barcodes With Python

Creating Fiduciary Markers With Python

Reading Fiduciary Markers With Python

Fiduciary Marker Use Cases

Build a User Interface With Gradio For Reading Barcodes

Build a Barcode Writing Application with Python

Roundup

Appendix

Reading and Writing QR Codes

A quick way to generate a QR code

More options for generating a QR code