Article summary

QR code is automatically generated using Python's qrcode. I want to write the identification number on the QR code at the same time, so I also use pillow and other tools to insert the characters.

Tool installation

Use qrcode to generate the QR code.

https://pypi.org/project/qrcode/

Please install qrcode.

pip install qrcode

Pillow is used to process the image.

https://pypi.org/project/Pillow/

Please install pillow.

pip install Pillow

QR code generation

import qrcode
from PIL import Image

img = qrcode.make("Hello World!")
img.save('test.png')

img.show()

You can check if the generated QR code can be read correctly by reading it at http://qrcode.red/.

QR code generation (detailed settings)

You can also make detailed settings.

import qrcode
from PIL import Image

qr = qrcode.QRCode(
    version=3,
    error_correction=qrcode.constants.ERROR_CORRECT_L,
    box_size=10,
    border=2,
)
qr.add_data('Hello World!')
qr.make(fit=True)

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

img.show()

version --A parameter that determines the number of cells and can be set to a value from 1 to 40. --1 is 21 cells x 21 cells, 2 is 25 cells x 25 cells, 40 is 177 cells x 177 cells --See below - https://www.qrcode.com/about/version.html
error_correction --Select from the following parameters at the error correction level - ERROR_CORRECT_L --Fixed 7% or less errors - ERROR_CORRECT_M --Default value --Fixed 15% or less errors - ERROR_CORRECT_Q --Fixed 20% or less errors - ERROR_CORRECT_H --Fixed 30% or less errors
box_size --Number of pixels in the box
border --Border thickness --Initial value 4 (minimum setting value)

Add margin

The function add_margin published in note.nkmk.me is convenient for adding and deleting margins to images.

Add margins to the top, bottom, left, and right of the image and resize with Python, Pillow

See the blog above for details on the function. This time I want to make a margin to display characters under the QR code, so add the size downward. The background color is white (#ffffff).

from PIL import Image
img = Image.open('test.png') #Load the image saved earlier
img_new = add_margin(img, 0, 0, 100, 0, '#ffffff')

img_new.show()

This function is useful for adjusting the image size because you can reduce the size by entering a negative number.

Change image size

I'll show you how to scale the image size for later use. You can scale the image with resize.

from PIL import Image, ImageDraw, ImageFont
img = Image.open('test.png') #Loading images
img_resize = img.resize((int(img .width / 2), int(img .height / 2)), Image.LANCZOS)

img_resize.show()

'Image.LANCZOS' is a parameter that specifies the compression filter. Select from the following. In general, the lower one has a lower compression ratio, but the image is cleaner. This parameter is optional, otherwise NEAREST will be applied automatically.

NEAREST --If nothing is specified, this will be selected
BOX
BILINEAR
HAMMING
BICUBIC
LANCZOS

Insert characters

I tried to insert characters by the method introduced in Image processing cheat sheet using Pillow that can edit images at once with Python.

from PIL import Image, ImageDraw, ImageFont
img = Image.open('test.png')
img_new = add_margin(img, 0, 0, 100, 0, '#ffffff')

draw = ImageDraw.Draw(img_new) 
font = ImageFont.truetype("./fonts/arial.ttf", 55) 
draw.text((10, 320), 'Hello! 12345', font=font, fill='#000000') 
img_new.save('test.png')

img_new.show()

You can change the font type. Please refer to the following to select. https://helpx.adobe.com/jp/x-productkb/global/cq08041028.html

When the image resolution of characters is rough

For small size QR codes, the characters inserted by the above method have the disadvantage of being rough. Therefore, save the high-resolution image enlarged by resize and size it appropriately with the tool that reduces the image size.

First, magnify the image with margins 10 times and insert large characters there.

from PIL import Image, ImageDraw, ImageFont
img = Image.open('test.png')
img_add = add_margin(img, 0, 0, 100, 0, '#ffffff')

img_resized = img_add.resize((int(img_add.width*10), int(img_add.height*10)), resample=Image.LANCZOS)

draw = ImageDraw.Draw(img_resized)
font = ImageFont.truetype("./fonts/arial.ttf", 530) 
draw.text((190, 3200), 'Hello! 12345', font=font, fill='#000000') 
img_resized.save('test.png')

img_resized.show()

I used the free software Fuji -Resizer- to reduce the image. Even hundreds of images can be reduced at once by dragging and dropping them onto the icon.

https://pcgenki.com/soft/resizer.htm

The characters are displayed neatly.

If you check it with image editing software, you can see that the resolution is not a problem even if you print it.

Mass production

By converting the existing code into a function, you can generate a large number of QR codes with serial numbers.

The automatic creation of the folder imitated the following article. Create Python folder Check if it already exists

import os
import qrcode
from PIL import Image, ImageDraw, ImageFont

def add_margin(pil_img, top, right, bottom, left, color):
    #Please copy the code from the article introduced earlier.
    return result

def qr_generator(number):
    qr = qrcode.QRCode(
        version=2,
        error_correction=qrcode.constants.ERROR_CORRECT_L,
        box_size=9,
        border=4,
    )
    qr.add_data('Hello!' + number)
    qr.make(fit=True)

    img = qr.make_image(fill_color="black", back_color="white")
    img.save('./my_qr_code/' + number + '.png')

    img = Image.open('./my_qr_code/' + number + '.png')
    img_add = add_margin(img, -15, -15, 45, -15, '#ffffff')
    img_resized = img_add.resize((int(img_add.width*10), int(img_add.height*10)), resample=Image.LANCZOS)
    
    draw = ImageDraw.Draw(img_resized)
    font = ImageFont.truetype("./fonts/arialbd", 450)
    num = number
    draw.text((200, 2550), 'Hello!' + num, font=font, fill='#000000') 
    img_resized.save('./my_qr_code/' + number + '.png', quality=95)

    #img_resized.show()


def main(total_num):
    new_path = "my_qr_code"#Folder name
    if not os.path.exists(new_path):#Check for directory
        os.mkdir(new_path)
    
    for number in range(total_num):
        qr_generator(str(1000+number))    
    
main(100)

Use Fuji -Resizer- to reduce the images created above to complete the process.

Mass generation of QR code with character display by Python