Base64

Sometimes we want to convert images to text (by using their base64 encoding) for web pages. This can reduce requests and make things go faster.

With the encoding/base64 package, we can use the EncodeToString func in Go to get a string from a byte slice containing the image. We can then create a data URI for our image.

An example

Here we have a "coin.jpg" image in the home directory. You will want to modify the path to the location of an image that exists.

package main

import (
    "bufio"
    "encoding/base64"
    "fmt"
    "io/ioutil"
    "os"
)

func main() {
    // Open file on disk.
    f, _ := os.Open("./coin.jpg")

    // Read entire JPG into byte slice.
    reader := bufio.NewReader(f)
    content, _ := ioutil.ReadAll(reader)

    // Encode as base64.
    encoded := base64.StdEncoding.EncodeToString(content)

    // Print encoded data to console.
    // ... The base64 image can be used as a data URI in a browser.
    fmt.Println("ENCODED: " + encoded)
}
ENCODED: /9j/2wBDAAQDAwQDAwQEAwQFBAQFBgoHBgYGBg0JCgg
[truncated]

Notes, program output

We truncate the output of the program, as the image is too large to be easily displayed. I verified (using an online tool) that the base64 representation is correct.

A summary

With base64, we can store images as text in an ASCII text file. This has advantages and disadvantages—too many to list here. But base64 is often useful in programming.