Base64

Many files contain binary data, and this data cannot be represented in plain text. But by converting it to base64, we can store the data within a string or text file.

Though it becomes larger, and thus loses efficiency, base64-encoded data can still be beneficial due to its portability. With the base64 module in Python, we can convert data to base64 encoding.

Example

This program requires a file named "test.jpg" in the working directory—please create one or copy one before running it.

Step 1 We read in the test.jpg file. We specify "rb" to read a binary file—this means read() will return a bytes object.

Step 2 We call b64encode to convert the bytes object into a encoded bytes object.

Step 3 For debugging purposes, we print the first 50 bytes of the encoded base64 bytes by using a Python slice.

Step 4 We convert the encoded base64 bytes object into an ASCII string by calling decode() on it.

Step 5 To create an HTML file with a data URI image, we use a format string literal. We specify the needed HTML and CSS.

Step 6 We write the example.html file which contains a base64-encoded image within a data URI, and then open it in a web browser.

import base64

# Step 1: read in the file.
with open("test.jpg", "rb") as f:
    # Step 2: encode as base 64 with b64encode.
    encoded = base64.b64encode(f.read())

    # Step 3: print first 50 bytes of the base 64 encoded file.
    print(encoded[0:50])

    # Step 4: encode bytes to string.
    result = encoded.decode("ascii")

    # Step 5: create a data url in an html string.
    html = f"<html><body style=\"background:url(data:image/jpeg;base64,{result}\"></body></html>"

    # Step 6: write to example html file.
    with open("example.html", "w") as f2:
        f2.write(html)
b'/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAYEBAQFBAYFBQYJBg'

Summary

Python is a batteries-included language, which means useful features like base64-encoding are built in. With just a module import and a method call, we can get converted base64 data.